FUR DYEING AND FUR DRESSING
PRINCIPLES AND PRACTICE
OF
FUR DRESSING AND FUR DYEIM
BY
WILLIAM E. AUSTIN, B.S.
CONSULTING CHEMIST TO THE FUR INDUSTRY
ILLUSTRATED
NEW YORK
D. VAN NOSTRAND COMPANY
EIGHT WARREN STREET
1922
, /?6> '
Copyright, 1922, by
D. VAN NOSTRAND COMPANY
All rights reserved, including that of translation into
foreign languages, including the Scandinavian
PRINTED IN THE UNITED STATES OF AMERICA
PREFACE
THE great increase in the use of furs during the past
few decades has caused the fur dressing and dye-
ing industry to rise from relative insignificance
to considerable importance as a branch of applied chemistry.
The past eight years, moreover, have witnessed the virtual
transference of the leadership in the dressing and dyeing of
furs from Europe to America, and in the quality and variety
of products, the domestic industry is now in every way the
equal of, and in many respects superior to the foreign. The
great bulk of American furs which formerly were sent to
Leipzig, Paris or London to be dressed and dyed, are now
being dressed and dyed in this country.
In spite of these facts, very little is generally known about
the nature and manner of the work constituting the dress-
ing and dyeing of furs. Even among members of other
branches of the fur trade, there is very little accurate in-
formation on the subject. Real knowledge concerning fur
dressing and dyeing is possessed only by those actually en-
gaged in the industry. The interest and efforts of scientists
and technologists have been enlisted to only a small extent
in the technical development of the industry. The reason
for this may be attributed to two related causes: first, the
almost monastic seclusion in which fur dressers and dyers,
particularly the latter, conducted their operations, and even
to-day the heavy cloud of mystery is being dispelled but
very slowly; and second, as a consequence of the first, the
lack of any reliable literature on the subject. Of the few
books which have been written on the industry of fur dress-
ing and fur dyeing (all of them either German or French),
most are hopelessly out of date, or contain no trustworthy
data; or, if they do have real merit, they cannot be obtained.
iii
551264
PREFACE
Numerous articles in the technical journals are of interest,
but they contain very little information of value.
This work is intended for a two-fold purpose: first, that
it may serve as a text-book for those who expect to make
fur dressing and dyeing their vocation. The fundamental
principles upon which the industry is based are discussed in
the light of the most recent chemical and technical develop-
ments, and the most important operations are treated fully
and systematically, and are illustrated with practical
examples.
Secondly, as a practical handbook for the worker in the
fur dressing and dyeing plant. The latest factory processes
and methods are described, and numerous working formulas
given. The formulas are all such as have been successfully
used on a large scale, and give satisfactory results when
applied under the proper conditions.
In addition, it is believed that the book will prove of
interest to chemists and other students of industrial chemis-
try, since it will be an introduction into a field of applied
chemistry, about which very little is known to those out-
side of the industry.
Thanks are due to Dr. L. A. Hausman, of Cornell Univer-
sity, for material used in Chapter II; to Dr. E. Lesser of
the American Dyewood Company, for information and
assistance on the subject of Vegetable Dyes; to the Gaskill
Chemical Corp., American Aniline Products, Inc., the
Cassella Company, and the Franklin Import & Export Co.,
for information about their products in connection with the
chapter on Oxidation Colors ; to F. Blattner, Fletcher Works,
Inc., S. M. Jacoby Co., Proctor & Schwartz, Inc., Reliable
Machine Works, Seneca Machine & Tool Co., Inc., and the
Turner Tanning Machinery Co., for the use of the cuts of
the various machines.
WILLIAM E. AUSTIN.
NEW YORK, May, 1922.
IV
TABLE OF CONTENTS
CHAPTER PAGE
PREFACE
I. FURS AND THEIR CHARACTERISTICS 1
Introductory. Knowledge of furs essential. Definitions.
Differences in furs of various animals. Effect of climate on
furs. Effect of age and season on furs. Durability and rela-
tive weights of furs. Description of important furs.
II. STRUCTURE OF FUR 21
The skin. The hair. Under-hair and top-hair. Chemical
composition of furs. Action of chemicals on the skin. Action
of chemicals on the hair.
III. FUR DRESSING: INTRODUCTORY AND HISTORICAL . 29
Objects of fur dressing. Origin of fur dressing. Use of fats.
Use of salt and alum. Use of the tannins. Early organiza-
tions of the fur workers. Modern organizations of the fur
dressing industry.
IV. FUR DRESSING: PRELIMINARY OPERATIONS 36
Flat skins and cased skins. Herbivorous and carnivorous
fur animals. Beaming or scraping. Softening the skins.
Cleaning; hydro-extracting. Fleshing.
V. FUR DRESSING: TANNING METHODS 45
Nature of the tanning process. Chief tanning methods.
Comparison of the tanning methods. Effect of dyeing opera-
tions on the dressing.
VI. FUR DRESSING: DRYING AND FINISHING 71
Importance of the drying process. Methods of drying. A
modern type of drying device. Oiling. Staking or stretching.
Beating and combing. Drum-cleaning. Unhairing and
shearing.
VII. WATER IN FUR DRESSING AND DYEING 85
Importance of water in dressing and dyeing. Water suitable
for dressing and dyeing. Soft water and hard water. Effects
of hardness in water.
VIII. FUR DYEING: INTRODUCTORY AND HISTORICAL... 90
Purposes of fur dyeing. Improvement of furs faulty in
color. Production of a uniform shade on furs. Dyeing furs
to obtain novel effects. Imitation of valuable furs on cheaper
skins. Difficulties due to the hair. Difficulties due to the
leather.
V
TABLE OF CONTENTS
CHAPTER PAGE
IX. FUR DYEING: GENERAL METHODS 98
Two methods of dyeing furs. Development of the dyeing
methods. The brush process. The dip process. Blending.
Drying and finishing the dyed furs.
X. FUR DYEING: KILLING THE FURS 106
Nature of the killing process. Old killing formulas.
Modern killing agents. Procedure of killing. Killing with
soda. Killing with lime. Killing with caustic soda.
XI. FUR DYEING: MORDANTS 114
Nature of mordanting. Purposes of mordanting. Theory
of mordants. Procedure of mordanting. Aluminum mor-
dants. Iron mordants. Copper mordants. Chromium mor-
dants. Tin mordants. Alkaline mordants.
XII. FUR DYEING: MINERAL COLORS USED ON FURS . 125
Mineral chemicals as fur dyes. Lead dyes. Potassium
permanganate as a dye. Other mineral dyes.
XIII. FUR DYEING: VEGETABLE DYES 128
Wood dyes. Old dye formulas. The vegetable dye mate-
rials. The tannin substances. Logwood. Fustic. Brazil-
wood. Other vegetable dyes. Characteristics of the wood
dyes. Application of the vegetable dyes. Application by the
brush process. Application by the dip process. Production
of shades other than black.
XIV. FUR DYEING: ANILINE BLACK 144
Dyeing of seal. Nature and history of Aniline Black.
Chemistry of the Aniline Black process. Three stages in the
formation of Aniline Black. Methods of applying Aniline
Black. One-bath Aniline Black. Oxidation Aniline Black.
Diphenyl Black. Aniline Black by Green's process. Aniline
Black by the dip method.
XV. FUR DYEING: OXIDATION COLORS 155
The original patents. The first Oxidation fur dyes. Early
difficulties. Solution of the difficulties. Progress with the
Oxidation dyes. Para-phenylene-diamine : a typical Oxida-
tion color. Range of shades obtainable. Mordants. Pro-
cedure in dyeing. Typical formulas. Combination of
Oxidation colors with other dyes.
XVI. FUR DYEING: COAL TAR DYES 171
Use of coal tar dyes. Basic colors. Acid colors; dyeing at
higher temperatures. Chrome colors. Vat dyes.
XVII. BLEACHING OF FURS 179
Purpose of bleaching. Steps in the bleaching process.
Methods of bleaching. Bleaching materials with reducing
action. Bleaching materials with oxidizing action. Blueing.
BIBLIOGRAPHY 185
vi
FUK DKESSING AND
y FUE DYEING
CHAPTER I
FURS AND THEIR CHARACTERISTICS
FURS have in general two uses: as the goods which
constitute the basis of the furrier's art, and as the
source of material for the hat manufacturer. In the
latter case, only the hair part of the fur is utilized in the
hat trade for the production of felt, the skin being either
made into leather, or used as the raw material for making
high-grade glue and gelatine. It is the furrier, therefore,
who uses the great bulk of furs, and requires them to be
dressed and dyed.
In discussing the dressing and the dyeing of furs, there
are, broadly speaking, two fundamental subjects to be con-
sidered: first, the raw materials employed, which are, of
course, the skins or pelts as they come from the trapper.
(Other substances used in fur dressing and dyeing are acces-
sories, and will be studied in connection with the processes.)
Second, all those operations, physical and chemical, manual
and mechanical, to which the raw skins have to be sub-
jected in order to obtain the finished fur, ready for use by
the furrier!}
Next to the inherent qualities of the fur skin, the future
value of a fur in a manufactured garment depends largely
on the dressing and dyeing it receives. It is in these opera-
tions that the beauty of the fur can be brought out to its
fullest degree, and if possible, enhanced, or the attractive
features can be marred or destroyed, and the fur rendered
quite worthless. Therefore, it is quite essential for the fur
FUR DRESSING AND FUR DYEING
dresser and the fur dyer in addition to the technical knowl-
edge and experience which are the fundamental requisites
of the industry, also to have more than a superficial famil-
iarity with the various kinds of furs. In fact, an accurate
knowledge of the nature and chief characteristics of furs in
general, and of the individual classes, in particular, is al-
most indispensable to obtain the best results. The habits
and habitats of the various fur-bearing animals are factors
which largely determine the constitution of the fur, and
the nature of the skin. There are as many different kinds
of fur hair, with as many different kinds of skin bearing the
hair, as there are classes of furs. The methods of dressing,
and often, if the furs are to be dyed, the manner of dyeing,
are determined by the nature of these component parts of
furs. Various chemicals affect furs in widely different ways.
The divergence with regard to the physical and chemical
properties of the classes of furs is such as to make almost
imperative a detailed knowledge of the typical members of
the many groups of commercial furs.
To be sure, there are many engaged in the dressing and
dyeing of furs, who never made a formal study of this phase
of the industry, but acquired their knowledge empirically,
and are apparently quite successful. It must not be denied,
that practise and experience, as in every field of enterprise,
are essential to obtaining the best results. But the time and
cost of acquiring this precious experience can be consider-
ably reduced by systematically studying the important
characteristics and properties of furs. These will be treated
briefly, but in sufficient detail to form a basis for discussing
the operations of dressing and dyeing.
^Fur-bearing animals are mammals whose skins are used
' in the manufacture of fur garments and other fur wearing
^ apparel. The skin, when it is removed from the animal is
4- called a pelt, or sometimes, in the case of large animals, a
hide. The pelt, after having been dressed and dyed, is
called a fury the skin part being referred to as the leather,
FURS AND THEIR CHARACTERISTICS
and the hair as the pelage. However, this terminology is
not strictly adhered to in practise, and the various terms are
often employed interchangeably.
The various fur-bearing animals differ considerably in -the
characteristics of the furs they yield. With few exceptions,
notably beaver and Alaska red fox, the depth of shade in-
creases as the habitat of the animal species is nearer the
equatorial regions. There seems to be a direct relationship'
between the intensity of color of the pelt, and the distance
from, or proximity to the polar, or the torrid regions. Thus,
white mammals, such as polar bear, ermine, white or Si-
berian hare, are found only in the northern lands. An ex-
ception is the sheep, which, due to its domestic nature, can
be found in almost all parts of the- civilized world. Tropical
animals on transportation to colder climates, have been
know T n to become lighter-haired when adapted to their new
environment. . The skins of animals living in dense woods
or forests, are generally of a deeper color than in animals
living in more open territory. As a general rule, fur-bearing ,
animals have darker hair on the back than on the sides and
belly. The badger, hamster, ratel and panda are exceptions
having the darker hair on the belly and sides, and the lighter
hair on the back. With regard to the intensity of color, the
skunk has the blackest fur, although some domestic cats
are also quite black. Other animals whose fur is nearly
black, are the black bear, and the black fox, which is a
variety of the silver fox, but the color is often of a brownish
shade. The colors which predominate among animals
of the fur-bearing variety, are white, black, brown, and
grey. Less common are yellow shades, and those known as
blue.
The quality of the fur on all mammals improves with cold, , /
and animals living at greater altitudes, with correspond-
ingly lower temperatures, have thicker and finer hair than
those living nearer sea-level. A cold winter generally pro-
duces fur of high quality and fine color- a mild winter may \
3
FUR DRESSING AND FUR DYEING
f cause the hair to be inferior. In all climates, animals found
in dense woods, have fur which is deeper, silkier, thicker,
and glossier than that of animals living in the open. Ani-
mals inhabiting inland lakes and rivers, have finer and softer
hair than those living near the coast or land exposed to sea
winds. In general, the hair of animals of the cold regions
is short, fine, soft, and downy, while the hair of animals of
warmer lands, is longer, stiffer, and harder.
Both the quality and color of the fur vary with the age
of the animal. The young usually have a thicker coat of fur
than adults, but the hair is too soft, and the skin generally
tender to be fit for use. In certain cases, particularly
(_ /the baby lambs, very young skins are especially prized, and
J eagerly sought, but extraordinary care has to be exercised in
; working with them. Fur is at its best when the animal is
between one and two years old. After this age, the fur be-
comes coarse and scraggy. The animal attains its fullest
growth of hair usually in the height of winter, and the fur
is best between then and very early spring. Before mid-
winter the hair is short and thin, and in the spring it be-
gins to shed, and will continue to fall out even in the dressed
fur. The color of the hair also becomes lighter with age,
and the new growth which generally comes in the fall is
darker than the old coat.
f Different members of the same species, will, other factors
such as age and season being equal, vary as to color and
quality. There may even be several different color phases
^of the same species of animal, such as the cross fox and the
silver fox, both of which are of the same genus as the red
fox; black muskrats are of the same class as the brown
variety, etc. The individual pelt likewise presents many
variations in color and nature of the hair. In some parts,
the hair is thicker and softer than others, and the color
varies in intensity and shade throughout the different sec-
tions of the skin.
Furs do not have differences confined to the hair part
FURS AND THEIR CHARACTERISTICS
only; the leather also presents considerable variation
among the different fur-bearing animals, especially in re-
gard to the weight and thickness. The durability of furs,
relatively considered under similar conditions of wear, also
t varies widely. In the following table the relative durability
of "dressed furs, and in certain instances also dyed furs, otter
being taken as standard, is given, as well as the weight in
ounces per square foot of skin of these furs.
Name gj 1 Durability Wt. in oz.
Otter = 100 per sq. ft.
Astrachan : 10 3 L-~
Bear, brown or black 94 7
Beaver, natural 90 4
Beaver, plucked 85 3% ^
Chinchilla 15 1% ^ I
Civet cat 40 2% '
Coney 20 3^
Ermine 25 \% *""
Fox, natural 40 3 2
Fox, dyed black 25 3
Genet 35 2%
Goat 15 4%
Hare 05 2%^ '
Krimmer 60 3
Kolinsky 25 3
- Leopard 75 4
Lynx 25 2%
Marten, Baum natural 65 2%
Marten, Baum blended 45 2%
Marten, Stone natural 45 2%
Marten, Stone dyed 35 2%
Mink, natural 70 S 1 ^ *-
Mink, dyed 35 _ 3%
Mink, Jap 20 x 3
Mole 07 \^> -1%
Muskrat 45 S 1 ^ u
Nutria, plucked 25 3%
Opossum, natural 37 3 ^
Opossum, dyed 20 3 ^
Opossum, Australian 40 3%
Otter, land 100 4V 2 *-
Otter, sea 100 4% ^
Persian lamb . 65 ZV
FUR DRESSING AND FUR DYEING
Name of Fur Durability Wt. in oz.
Otter = 100 per sq. ft.
Pony, Russian 35 3Mi
Rabbit 05 2V^
Raccoon, natural 65 2 1 /4 ^
Raccoon, dyed 50 2% r/
Sable 60 2V 2
Sable, blended 45 2V 2
Seal, fur 80 3V 2 -
Seal, fur dyed 70 3V 8
Skunk, tipped 50 2 7 /s
Squirrel, grey 20-25 1%
Wolf, natural 50 6y 2 v
Wolverine 100 7 ^
In estimating the value of a fur, many factors have to
be considered. There is no one standard by which the
skins are judged, each kind of fur having its own criterion.
However, the general points by which raw furs are graded
are, color, size, origin, quality and quantity of hair, con-
( dition of leather, date or season of trapping, methods of
handling, etc. Beaver, for example, is graded as large,
medium, small and cubs. Red foxes, first, into Alaska,
Labrador, and Nova Scotia, and then these divisions are
classed as large, medium and small. Skunks are graded
according to the amount of white on the skin, the less white,
the more valuable the fur.
The qualities which make a fur desired depend first of
all on the nature of the fur itself. Pretty color, luster,
thickness, softness, length, uniformity and regular fall of
the hair are the chief points to be considered. While
the leather part of the fur is of secondary importance
in the evaluation of a fur, it must possess strength, light-
ness of weight, and when properly dressed, should be supple
and have a certain firmness or ' feel.' The abundance or
scarcity of a fur-bearing animal also determines the value
of the fur. Furs which are always comparatively rare,
such as silver fox, Russian sable, chinchilla, etc., are always
highly prized. ' In this connection, circumstances which
FURS AND THEIR CHARACTERISTICS
tend to decrease the number of available pelts of any par-
ticular animal, such as pestilences, gradual extermination
due to excessive trapping, prevention of trapping, by pro-
tective laws, also affect the value of a fur. A third factor\
which has an influence on the value of furs, is the prevailing \
style or fashion. Many kinds of furs which are both beauti-
ful and rare, such as Russian sable or chinchilla, are prac-
tically unaffected by the whims of fashion. But a fur of
ordinary value may at times become so popular, that the
demand for it will cause its price to be greatly increased.
Similarly, a fur which has enjoyed a considerable vogue,
may pass out of demand for a time and consequently depre-
ciate in value.
A detailed description of the various furs used in com-
merce is not within the scope of this work, because such
an account rightly belongs in a book on zoology. However,
it is desirable that the reader who is interested in the dress-
ing and dyeing of furs should have at least a passingjacjA
quaintance with the chief furs used in commerce, together l
with such of their individual characteristics as are of im-
portance. The figures given are for the average dressed
skin. 1
Astrachan, see Lambs.
Badger. 2x1 ft. This is one of the few animals
whose fur is darker on the belly than on the back. The
American sorts have coarse, thick under-hair of a pale fawn
or stone color, with a growth of longer black and white hairs
3-4 inches long. The Japanese varieties are usually dyed for
imitation skunk. The American kind is also dyed occasion-
ally but is mostly used natural. Badger hair is very exten-
sively used for ' pointing/
Bear, Black. 6x3 ft. Has fine, dark brown under-
hair, with bright, flowing black top-hair 4 inches long. The
fur of cubs is nearly as long, although the skins are much
1 Descriptions after W. S. Parker, Deputy Chairman, Fur Section ot
London Chamber of Commerce, in Enclyclopedia Britannica, llth Ed.
FUR DRESSING AND FUR DYEING
smaller, and the hair is finer, softer, and lighter-pelted. The
best skins are from Canada,
Bear, Brown. 6 x 3 ft. Similar to the Black Bear, but
more limited in number. The color ranges from a light yel-
low to a rich dark brown. The best and most valuable sorts
come from the Hudson Bay territory, inferior skins coming
from Europe and Asia,
Bear, White. 10 x 5 ft. This is the largest of the
bears. The hair is short and close except on the flanks,
while the color ranges from white to yellow. The best skins
come from Greenland, the whitest being the most valuable.
Beaver. 3 x 2 f t. This is the largest of the rodents,
and is very widely used; formerly to a great extent in the
hat trade. The under-hair is close and of a bluish-brown
hue, and nearly an inch deep. The over-hair is coarse,
bright black or reddish-brown in color, and is usually
plucked out, as the under-hair is the attractive part of the
fur. The darkest skins are the most valuable. Formerly
beaver was used to dye in imitation of seal, but more suit-
able furs are now used.
Broadtail, see Lambs.
Caracul, see Lambs.
Cat, Civet. 9 x 44 inches, with short, thick and dark
under-hair, and silky, black top-hair with irregular white
markings. It is similar to the skunk, but is lighter, softer,
less full, and has no disagreeable odor.
Cat, House. 18 x 9 inches. Is mostly black and dark
brown, the best skins coming from Holland. The hair is
weak, coming out with the friction of wear. In the trade,
the black variety is known as genet.
Chinchilla. 12 x 7 inches. This is one of the rarest
and most beautiful furs. It comes from Bolivia and Peru,
where, due to the uncontrolled trapping of the animal,
it is becoming scarce, and this compelled the governments
to enact laws prohibiting the taking of chinchilla for a cer-
tain period. The fur is of a delicate blue-grey, with black
8
FURS AND THEIR CHARACTERISTICS
shadings, the fur being 1-1 J inches deep. Unfortunately,
the skin is quite perishable.
Chinchilla, La Plata. 9 -X 4 inches. Incorrectly called
" bastard chinchilla " in the trade. It is a similar species
to the Bolivian chinchilla, but due to the lower altitude and
warmer climate of its habitat, is smaller, with shorter and
less pretty hair, the color of the under-hair being darker,
and of the top-hair less pure. It is quite as undurable as
true chinchilla.
Chinchillone. 13 x 8 inches. Is also from South
America. The fur is longer, weaker, poorer and yellower
than real chinchilla, but the skins are often dyed in shades
closely resembling the natural chinchilla.
Ermine. 12 x 2J inches. The under-hair is short and
even, with the top-hair slightly longer. The leather is light,
close in texture, and quite durable. In mid-winter the color
is pure white, except the tip of the tail, which is usually
quite black. The best skins are from Siberia.
Fisher. 30 x 12 inches, with tail 12-18 inches long. It
is the largest of the marten family. The under-hair is deep,
and of a dark shade, with a fine dark, glossy and strong top-
hair, 2 or more inches long. The best skins are from Canada.
The fur is something like a dark silky raccoon, while the tail,
which is very highly prized, is almost black.
Fitch. 12 x 3 inches. It is of the marten species, and
its common name is polecat. The under-hair is yellow and
J of an inch deep. The top-hair is black, 1-J-l f inches long,
very fine and open in growth, and not so close as the mar-
tens. The largest and best skins are from Denmark, Hol-
land and Germany. The Russian skins are smaller, silkier,
and are usually dyed as a substitute for sable.
Fox, Blue. 24 x 8 inches. The under-hair is thick and
long, while the top-hair is fine and not so plentiful as in
other foxes. It is found in Alaska, Hudson Bay Territory,
Greenland and Archangel. Although called blue, the color
is really of a slaty or drab shade. The skins from Archangel
9
FUR DRESSING AND FUR DYEING
are more silky and of a smoky bluish color, and being scarce
are most valuable. The white faxes which are dyed a smoky
blue are brilliant and quite unlike the browner shades of the
blue-fox.
Fox, Cross. 20 x 7 inches. The skins generally have a
pale yellow or orange tone, with some silver points, and a
darkish cross marking on #ie shoulders, on account of which
the animal got its name. Some are very similar to the pale
red foxes of Northwest America. The darkest and best
skins are from Labrador and Hudson Bay, those from
lower latitudes being inferior.
Fox, Grey. 27 x 10 inches. Has a close dark drab
under-hair, with coarse regular, yellowish, grizzly-grey top-
hair. The majority of the skins come from Virginia and
southwestern U. S. A. Those from the west are larger and
brighter-toned.
Fox, Kit. 20 x 6 inches. The under-hair is short and
soft, as is also the top-Kair, which is a very pale grey mixed
with some yellowish-white hairs. It is the smallest of the
foxes, and is found in Canada and northern United States.
Fox, Red. 24 x 8 inches, although some kinds are
larger. The under-hair is long and sof% and the top-hair
is plentiful and strong. The colors range from pale yellow
to a dark red, some being very brilliant. It is widely found
in northern America, China, Japan, and Australia. The
Kamchatka foxes are exceptionally fine and rich in quality.
Farther north, near the open sea, the fur is coarse. The
skins have an extensive use, both natural and dyed. They
are dyed black in imitation of the black fox, or these when
pointed with badger or other white hair to imitate the silver
fox.
Fox, Silver. 30 x 10 inches. The under-hair is close
and fine, and the top-hair, which is black to silvery, is 3
inches long. The fur on the neck usually runs almost black,
and in some cases the black extends over half the length
of the skin. When all black, it is a natural black fox, and
10
FURS AND THEIR CHARACTERISTICS
is exceedingly rare and high-priced. The silver fox is very
valuable, the finest wild skins coming from Labrador. The
tail is always tipped white. The majority of the silver fox
pelts that reach the market today are bred on ranches in
Canada and the United States.
Fox, White. 20 x 7 inches. It is usually small and in-
habits the extreme northern sections of Hudson Bay, Labra-
dor, Greenland, and Siberia. The Canadian are silky-haired
and inclined to a creamy color, while the Siberian are whiter
and more woolly. The under-hair is generally of a bluish-
grey tone, but the top-hair in winter is usually full enough
to hide such a variation. Those skins which have under-hair
that is quite white are rare and much more expensive than
the others. In summer specimens of these species have
slightly discolored coats, the shades resembling those of the
blue fox. The skins which are not perfectly white are
bleached, or if they cannot be bleached sufficiently white
they are dyed various shades of smoke color, blue-greys and
also imitation blue fox.
Goat. The size varies greatly. The European, Arabian
and East Indian varieties are used mainly for leather and
wool. Many from Russia are dyed black for rugs. The
hair is brittle, with poor under-hair, and is not durable. The
Chinese export many skins in grey, black and white, made
into rugs of two skins each. Frequently the skins are dyed
black or brown in imitation of bear.
Hamster. 8x3^ inches. A destructive rodent found
largely in Russia and Germany. The fur is very flat and
poor, of a yellowish -brown color, with a little marking of
black. On account of its lightness it is used for linings; oc-
casionally it is dyed.
Hare. 24 x 9 inches. The common hare of Europe is
used mostly for the hatters' trade. The white hares of
Russia, Siberia, and other northern regions are the ones
mainly used for furs. It is whitest in mid-winter, and the
fur on the flanks is longer than that on the back. The hair is
11
FUR DRESSING AND FUR DYEING
brittle and not durable, and the leather is quite as bad. Yet
the skins are used to dye imitations of more than a dozen
different furs. The North American hares are also dyed
black and brown.
Kangaroo. -- The sizes vary greatly, the larger kinds be-
ing generally used for making leather. The sorts used for
fur are, blue kangaroo, bush kangaroo, wallaroo, rock
wallaby, swamp wallaby, and short-tailed wallaby. Many
of the swamp wallabies are dyed imitation skunk, and look
quite attractive. The colors are generally yellowish or
brown, some in the swamp variety being dark brown. The
skins are quite strong. The rock wallabies are soft and
woolly, and often have a bluish tone. They are used for
rugs.
Kolinsky. 12x2^ inches. It is of the marten family.
The under-hair is short and rather weak, but regular, as is
also the top-hair. The color is usually a uniform yellow.
They are generally dyed in imitation of other members of
the marten family. It is very light in weight, and the best
skins are obtained from Siberia. The tails are used for
artists' " sable " brushes.
Lambs. Those of commercial interest are from South
Russia, Persia, and Afghanistan, and include Persian Lamb,
Broadtail, Astrachan, Shiraz, Bokhara, Caracul, and
Krimmers.
The Persians are 18 x 9 inches, and are the finest and
best. When properly dressed and dyed they should have
regular, close, bright curls, varying from small to very large
and if of equal size, regularity, tightness and brightness,
their value is inestimable.
All the above lambs, except krimmer, are naturally a
rusty black or brown, and are in most cases dyed a jet black.
Luster cannot be imparted where naturally lacking.
Broadtails, 10 x 5 inches, are the young of the Persians,
killed before the wool has had time to develop beyond the
flat wavy state. They are naturally of exceedingly light
12
FURS AND THEIR CHARACTERISTICS
weight, and when of an even pattern possessing a lustrous
sheen are costly. The pelt, however, is too delicate to resist
hard wear.
Astrachan, Shiraz, and Bokhara lambs, 22 x 9 inches, -
are of a coarser and looser curl. Caracul lambs are the very
young of the astrachan, and the finest skins are almost as
effective as the broadtails, although not so fine in texture.
Krimmers, 24 x 10 inches are grey lambs obtained from
Crimea. They are of a similar nature to the caraculs, but
looser in curl, and ranging in color from a very light to a
dark grey, the best being pale bluish-greys.
Slink lambs come from South America and China. The
South American are very small, and generally those are
still-born. They have a particularly thin pelt, with very
close wool of minute curls. The Chinese sorts are much
larger.
Leopard. 3x6 feet long. There are several kinds, the
chief being the snow leopard or ounce, Chinese, Bengal, Per-
sian, East Indian, and African. The first variety inhabits
the Himalayas, and has a deep, soft fur, quite long as com-
pared with the Bengal sort. The colors are pale orange and
white with dark markings. The Chinese are of a medium
orange-brown color and full in fur. The East Indian are less
full and not so dark; the Bengal are dark and medium in
color with short, hard hair. The African are small, with
pale lemon-colored ground, and very closely marked with
black spots.
Lynx. 45 x 20 inches. The under-hair is thinner than
in the fox, but the top-hair is fine, silky and flowing, 4 inches
long, of a pale grey, slightly mottled with fine streaks and
dark spots. The fur on the flank is longer, and white, with
very pronounced markings of dark spots, and this part of
the skin is generally worked separately. Skins with a bluish
tone are more valuable than those with a sandy or reddish
hue. The lynx inhabits North America as far south as
California. The best skins come from Hudson Bay, and also
13
FUR DRESSING AND FUR DYEING
Sweden. They are generally dyed black or brown, similar
to dyed fox.
Marmot. 18 x 12 inches. A rodent found largely in
the south of Germany. The fur is yellowish -brown, rather
harsh and brittle, and without under-hair. Also found in
North America, China, and the best skins come from Russia.
It is dyed brown in imitation of mink or sable, the stripes
usually being put on in the completed garment.
Marten, Baum. 16 x 5 inches. Also called Pine
Marten, and is found in the woods and mountains of Russia,
Norway, Germany and Switzerland. It has a thick under-
hair with strong top-hair, and ranges from a pale to a dark
bluish-brown. The best are from Norway, are very durable
and of good appearance, and a good substitute for the
American sable.
Marten, Japanese. 16 x 5 inches. It is of a woolly na-
ture with rather coarse top-hair, and quite yellow in color.
It is dyed, but it is not an attractive fur, lacking a silky,
bright and fresh appearance.
Marten, Stone. Size and quality similar to the baum
marten. The color of the under-hair is stony white, and the.
top-hair is a very dark brown, almost black. Skins of a pale
bluish tone are used natural, while less clear colored ones are
dyed, usually in Russian sable shades. They are found in
Russia, Bosnia, Turkey, Greece, Germany, and France,
the best coming from Bosnia and France.
Mink. 16 x 5 inches. Is of the amphibious class, and
is found throughout North America, as well as in Russia,
China and Japan. The under-hair is short, close and even,
as is also the top-hair, which is very strong. The best skins
are very dark,. and come from Nova Scotia. In the central
states the color is a good brown, but in the northwest and
southwest, the fur is coarse and pale. It is very durable and
an economic substitute for sable. The Russian species is
dark, but poor and flat in quality, and the Chinese and Japa-
nese sorts are so pale that they are always dyed.
14
FURS AND THEIR CHARACTERISTICS
Mole. 3 J x 2^ inches. Is plentiful in the British Isles
and Europe, and is much in demand on account of its vel-
vety fur of a pretty bluish shade. Although the skins are
comparatively cheap, the cost of dressing is high on account
of the considerable amount of labor involved. The pelt is
very light in weight, but does not resist well the friction of
wear.
Monkey, Black. 18 x 10 inches. The species usually
found on the west coast of Africa, is the one of interest to
the fur trade. The hair is very long, very black and bright,
with no under-hair, and the white pelt is very noticeable by
contrast.
Muskrat, Brown, Black, Russian. 12 X 8 inches. A
very prolific rodent of the amphibious class, obtained in
Canada and the United States. It has a fairly thick and
even brownish under-hair, and a rather strong, dark top-
hair of medium density. It is a durable and not too heavy
fur. It is used natural, but recently the plucked, sheared
and dyed skins have found a very extensive use as Hudson
seal, an imitation of real seal. The so-called black variety
of muskrat is found in New Jersey and Delaware, but only
in comparatively small numbers. The Russian is also very
small and limited in numbers. It is of a pretty silvery-blue
shade with even tinder-hair, with very little silky top-hair,
and silvery-white sides, presenting altogether a marked
effect.
Nutria. 20 x 12 inches. Is a rodent about half the size
of the beaver, and when plucked, has only about half the
depth of fur, which is not so close. It is often dyed a seal
color, but its woolly nature renders it less effective than the
dyed muskrat. The skins are obtained from northern South
America.
Opossum, American. 18 x 10 inches. Is a marsupial,
the only one of its class found outside of Australia. The
under-hair is of a very close frizzy nature, and nearly white,
with long bluish-grey top-hair mixed with some black. It
15
FUR DRESSING AND FUR DYEING
is found in central sections of the United States, and is fre-
quently dyed imitation skunk.
Opossum, Australian. 16 x 8 inches. Is of a totally
different nature from the American. Although it has fur-
hair and top-hair, the latter is sparse and fine, so that the
fur coat may be considered one of close even under-hair.
The color varies according to the district of origin, from
blue-grey to yellow with reddish tones.
Those from near Sidney are a light clear blue, while those
from Victoria are a dark iron-grey, and stronger in the fur-
hair. The most pleasing shade of grey comes from Adelaide.
The reddest are the cheapest. The ring-tailed opossum,
7X4 inches, has a very short, close and dark grey under-fur,
some almost black, but the skins are not used extensively.
The Tasmanian opossum, grey and black, 20 x 10 inches,
is of a similar description, but larger, darker, and stronger in
the under-hair.
Otter, River. The size varies considerably, as does also
the length of the fur, according to the origin. It is found
in greatest numbers in the coldest northern regions, and with
the best under-hair, the top-hair being unimportant, as it is
plucked out. Most of the best river otters come from
Canada and the United States, and average 36 x 18 inches.
The skins from Germany and China are smaller and shorter
furred. The colors of the under-hair vary from very dark
brown to almost yellow. Both the fur and the leather are
extremely strong, and many skins are dyed imitation seal
after plucking.
Otter, Sea. 50 x 25 inches. Is one of the most beauti-
ful of furs. The under-hair is of a rich, dense, silky nature,
with short and soft top-hair, which is not plucked. The
colors range from a pale grey-brown to a rich black, and
many skins have a sprinkling of white or silver-wiiite hairs.
The blacker the under-hair, and the more regular the silver
points, the more valuable is the skin.
Pony, Russian. --This is a comparatively cheap, but
16
FURS AND THEIR CHARACTERISTICS
very serviceable fur, and possesses some very desirable
qualities. It has a thin leather, -but is also scantily haired.
Young pelts have a design on them somewhat similar to
broadtail lambs, or moire astrachans, but this design is lost
to a considerable degree by dyeing the furs. The hair,
which is very glossy, is generally dyed black, although the
natural pelts are also worn extensively.
Rabbit. 10 x 16 inches. The fur is thick and fine, but
the pelt is very weak. It is a native of central Europe,
Asia, North and South America, New Zealand and Aus-
tralia. The color ranges from white to black. France, Bel-
gium and Australia are the greatest producers of rabbits
suitable for dyeing black, the so-called French seal, for
which they are mostly used. At the present time the dyeing
of rabbits constitutes a considerable percentage of the total
fur-dyeing operations in this country. The most varied
shades are produced on rabbit, and it probably is the basis
of the greatest number of dyed imitations of better furs. In
addition to the French seal, or sealine, rabbit is dyed in
imitation of beaver, mole, etc.
Raccoon. 20 x 12 inches. Varies considerably in size,
quality and color of the fur, according to the part of North
America in which it is found. The under-hair is 1-H inches
deep, pale brown, with long top-hair of a dark and silvery-
grey mixture of a grizzly type, the best having a bluish tone,
and the cheapest a yellowish or reddish-brown. The best
skins come from the northern part of the United States.
The skins have a wide use natural, but are also dyed dark
blue, or imitation skunk, the latter being a very effective and
attractive substitute, and extensively used. Sometimes the
skins are plucked, and if the under-hair is good, the effect
is similar to a beaver.
Sable, American and Canadian. 17 x 5 inches. The
skins are sold in the trade as martens, but since many of the
skins are of a very dark color, and almost as silky as Russian
sable, they have come to be known as sable. The prevailing
17
FUR DRESSING AND FUR DYEING
color is a medium brown, while many are quite yellow.
These pale skins have been dyed so well that they can
cheaply substitute Russian sable. The finest skins are from
the Eskimo Bay and Hudson Bay districts, the poorest from
Alaska.
Sable, Russian. 15 x 5 inches. Belongs to a species of
marten similar to the European and American, but much
more silky in the texture of the fur. The under-hair is
close, fine and very soft, the top-hair is regular, fine and
flowing, and silky, ranging from 1^ to 2^ inches in depth.
In color they vary from a pale stony or yellowish shade to
a rich, almost black, dark brown, with a bluish tone. The
leather is exceedingly close and fine in texture, very light in
weight, and very durable. The Yakutsk;, Okhotsk, and
Kamchatka sorts are good, the last being the largest and
fullest-furred, but of less color density than the others. The
most valuable, are the darkest from Yakutsk in Siberia, par-
ticularly those having silvery hairs evenly distributed over
the skin, but these furs are very rare.
The Amur skins are paler, but often of a pretty, bluish
tone, with many interspersed silvery hairs. The fur is not
so close or deep, but is very effective nevertheless. The
paler skins from all districts are now tipped, the tips of the
hair being stained dark, the fastest dyes being used, and
only an expert can detect them as differing from the natural
shades.
Seal, Fur. The sizes range from 24 x 15 inches to
15 x 25 inches, the width being the widest part of the skin
after dressing. The most useful skins are the pups 42 inches
long, the quality being very good and uniform. The largest
skins, known as wigs, and ranging up to 8 feet in length,
are uneven and weak in the fur. The supply of the best
sort is chiefly from the northern Pacific, Pribilof Islands,
Alaska, northwest coast of America, Aleutian Islands, and
Japan. Other kinds are taken from the south Pacific re-
gions. The dressing and dyeing of seal takes longer than for
18
FURS AND THEIR CHARACTERISTICS
any other fur, but when finished, it has a fine, rich effect,
and is very durable.
Seal, Hair. This is chiefly used for its oil and leather,
and not for its fur. It has coarse, rigid hair, and no under-
hair.
Skunk, or " Black Marten." 15 x 8 inches. The
under-hair is full, and fairly close, with glossy, flowing top-
hair about 2^ inches long. The majority of the skins have
two stripes of white hair extending the whole length of the
skin. These were formerly cut out, but more recently are
dyed the same color as the rest of the skin. They are widely
found in North and South America. The best are from Ohio
and New York. The skunk is naturally the blackest fur,
is silky and very durable.
Squirrel. 10 x 5 inches. This size refers to the Russian
and Siberian types, which are practically the only kind im-
ported for fur, other species having too poor a fur to be of
great commercial interest. The back of the Russian squirrel
has an even, close fur, varying from a clear bluish -grey to
a reddish -brown, the bellies in the former being of a flat
quality and white, in the latter, yellowish. The backs are
worked up separately from the bellies. The pelts, though
light in weight, are tough and durable. The tails are dark
and very small, and considerably used.
Tiger. The size varies, the largest measuring about 10
feet from the nose to the root of the tail. It is found
throughout India, Turkestan, China, Mongolia, and the
East Indies. Coats of the Bengal variety are short and of a
dark orange-brown with black stripes. Those from other
parts of India are similar-colored, but longer in hair, while
those from the north and China are not only large in size,
but have very long soft hair of a delicate orange-brown, with
very white flanks, and marked generally, with the blackest
of stripes.
Wolf. 50 x 25 inches. Is closely allied to the dog
family, and very widely distributed over the world. The
19
FUR DRESSING AND FUR DYEING
best are the full-furred skins of a very pale bluish-grey with
fine, flowing black top-hair, from the Hudson Bay district.
Those from the United States and Asia are harsher and
browner. The Siberian is smaller than the North American,
and the Russian still smaller. A large number of prairie-
dogs, or dog-wolves, is also used for cheaper furs.
Wolverine. 16 x 18 inches. Is a native of America,
Siberia, Russia, and Scandinavia, and is of the general na-
ture of the bear. The under-hair is full and thick, with
strong, bright top-hair about 2-J inches long. The color is of
two or three different shades of brown on one skin, the
center being dark, and presenting the general appearance
of an oval saddle, bordered with a rather pale shade of
brown, and merging to a darker shade towards the flanks.
This peculiar character stamps it as a distinguished fur.
It is expensive, and quite valuable on account of its excellent
qualities.
Wombat, Kaola or Australian Bear. 20 X 12 inches.
It has a light grey or brown, close, thick under-hair -J inch
deep, and no top-hair, with a rather thick, spongy pelt. It
is cheap, and well suited for rough wear.
20
CHAPTER II
STRUCTURE OF FUR
4 'MJR is made up of two main components, the hair
|H and the skin, and each of these has a very complex
-"- ^structure j;
In the living animal the skin serves as a protective cover-
ing, and also constitutes an organ of secretion and of feel-
ing.;, consequently it is of a highly complicated nature. The
skin of all fur-bearing animals is essentially the same in
s strtrcture,- -although varying considerably as to thickness
and texture. It consists of two principal layers^ which are
entirely different in structure and purpose, and correspond-
ingly different in both physical and chemical respects: the
epidermis, epithelium or cuticle, which is the, outer layer,
and the derinis or corium. which is. the true skin. (Fig. 1A ).
The epidermis is very thin as compared with the-fiociuaa.Qjg A
'.ftfl outer layer consists of a tissue of cells, somewhat analo-
gous to the horny matter of nails and hair. The inner sur-
face, called the ' rete malpighi,' -rests on f>>p tmp sVln ar>H
is a soft, mucous layer of cells. These cells are spherical
when first formed, but as they approach the surface become
flattened, and dry up, forming the horny outer layer of the
epidermis, which is constantly throwing off the dead scales,
and which is constantly being renewed from below.^Jt., is ,_
from this inner layer of the epidermis that the hair, the
sweat-glands, and the fat-glands are developed.
The corium, or true skin, consists essentially of white,
interlacing fibres of the kind known as connective tissue.
These fibres are themselves made up of extremely fine
smaller fibres, or fibrils, cemented together by a substance
of-srsonrewhat different nature from the fibres, the coriin.
Towards the center of the skin, the texture of the interweav-
21
FUR DRESSING AND FUR DYEING
ing fibres is looser, becoming much more compact at the sur-
face just beneath the inner layer of the epidermis. This
part of the corium is so exceedingly close that the fibrils are
scarcely recognizable. It is in this part that the fat-glands
are situated, while the hair-roots and sweat-glands pass
through it into the looser texture of the corium. The sur-
face next to the flesh is also closer in structure than the
middle portions of the skin, and has somewhat of a mem-
branous character due to the fibres running almost parallel
to the surface of the skin. The skin is joined to the body
proper by a network of connective tissue, frequently full
of fat-cells. This layer, together with portions of theJlesh
which may adhere to it, is removed by the process called
' fleshing/ and this side of the skin is known as the flesh
side. The corium also contains a small proportion of yellow
fibres, known as ' elastic fibres/ which differ physically and
chemically from the rest of the skin substance.
During the course of the development of the embryo ani-
mal, a small group of cells forms like a bulb on the inner side
of the epidermis, above a knot of very fine blood-vessels in
the corium. This group of cells grows downward into the
true skin, and the hair-root which is formed within it, sur-
rounds the capillary blood-vessels, drawing nourishment
from them, and thus forming the papilla. (Fig. 1A).
Smaller projections also form on the bulb, and the fat- glands
are gradually developed. The sweat-glands are formed in
a manner similar to the development of hair.
The individual hair fibre is quite, as complicated in struc-
ture as the skin, and is made up of four distinct parts.
(Fig. IB). 1
(^ The medulla, or pith, is the innermost portion of the hair,
and is composed of many shrunken cells, often connected
by a network which may fill the medullary column partially
or wholly.
1 Descriptions and figures taken from " Mammal Fur Under the Mi-
croscope," by Dr. L. A. Hausman, in Natural History, Sept.-Oct., 1920.
22
STRUCTURE OF FUR
Surrounding the medulla is the cortex, which is made up
of spindle-shaped cells fused into a horny, almost homo-
geneous, transparent mass, and forming a large proportion
of the hair shaft.
In the majority of the fur-bearing animals, there is dis-
tributed within and among the cells of the cortexji pigment
in the form of granules or minute particles, arranged in
the different hairs in fairly definite and characteristic pat-
terns. It is to these pigment granules that the color of the
hair is due primarily. In some cases the coloring matter
ofThe shaft is uniformly diffused and not granular.
A. STRUCTURE OF SKIX.
Cuticle
Cortex
Medulla
Epidermis (outer layer)
Epidermis (inner layer)
True skin or Dermis
Oil gland
Muscles which move the
hair
Follicle (inner layer)
Follicle (outerlayer)
Papilla inclosed in Bulb
Root sheath (inner Jayer)
Root sheath (outer layer)
. Blood and nerve supply
No the hair
FIG. 1
Cuticle
Cortex
Medulla.
/Cuticular
\sca
B. STRUCTURE OF HAIR.
The outermost coat of the hair, or cuticle, is composed
of thin7 colorless, transparent scales of varying forms and
sizes, and arranged in series like the shingles of a roof. It
is on these scales that the lustre or gloss of the hair depends.^
"SniceTustre is due to the unbroken reflection of light from
the surface of the hair, the smoother the surface, the glossier,
it will appear. When the scales of the cuticle are irregular
and uneven, the surface of the hair will not be uniform and
23
FUR DRESSING AND FUR DYEING
smooth, and the light reflected from it will be broken and
scattered, and consequently the hair will not possess a high
degree of lustre. As a rule, the stiff, straight hairs have the
most regular and uniform arrangement of the scales of the
cuticle, and hence are the smoothest and glossiest.
Fur hairs are in general either circular or elliptical in
cross-section, those which are circular being straight or only
slightly curved, while those which are elliptical in cross-sec-
tion are curly like the hair of the various kinds of lambs.
Most fur-bearing animals have two different kinds of hair
on their bodies. Nearest to the skin is a coat of short, thick,
soft and fine hair, usually of a woolly nature, and called the
under-hair, under-wool, or fur-hair. Overlying the fur-hair
is a protective layer of hair, longer and coarser than the
under-hair, and usually straight, hard, smooth and glossy.
This is called the top-hair, over-hair, guard-hair or protec-
tive hair. In some furs, the top-hair constitutes one of the
chief elements of their beauty, while in others, the top-
hairs are removed, so as better to display the attractive
features of the under-hair. The roots of the top-hair are
generally deeper in the skin than those of the fur-hair, and
in some instances where the top-hair is removed, as in the
seal, the roots are destroyed by the action of chemicals
applied to the skin side, the roots of the fur-hair being
wholly unaffected by this treatment.
The fur-hair and the top-hair in the same animal have
different medullary and cuticular structures, and these
characteristics may be used to distinguish the two kinds of
hair. Figs. 2A and B illustrate these differences. In each
case, the two large hairs on the left of the illustration are
the guard-hairs, showing respectively the cuticular scales
and the medulla. On the right are the two fur-hairs showing
the scales and the medulla.
Although composed of many different kinds of tissues,
anti varying so greatly in physical structure, both the skin
and the hair belong to the same class of chemical com-
24
STRUCTURE OF FUR
pounds, namely the proteins. These are highly complex
substances, forming the basis of all animal and vegetable
tissues. There are many different kinds of proteins, varying
somewhat in their constitutions, but all show, on analysis
the following approximate composition of chemical
elements :
Carbon 50-55%
Hydrogen 6.5-7.3%
Nitrogen 15-17.6%
Oxygen 19-24%
Sulphur 0.3-5%
The principal kinds of proteins found in the various fur
structures are albumins, keratin, collagen, and mucines.
Albumins, of which the white of egg is the most familiar
A. HAIR OF EUROPEAN BEAVER.
a. TOP-HAIR, b. UNDER-HAIR.
FIG. 2 B
B. HAIR OF SKUNK.
a. TOP-HAIR, b. UNDER-HAIR.
variety, occurs to some extent in the corium as serum in the
blood-vessels, and also as the liquid filling the connective
tissues, known as the lymph. They are soluble in cold
water, but when heated to about 70 C., they coagulate and
are then insoluble. Concentrated mineral acids and strong
alcohol will also effect coagulation.
Keratin is the chief substance of which all horny parts of
the animal body are composed, such as the hair, nails or
hoofs. It is the principal constituent of the hair, the epi-
dermis, and the walls of the cells of the inner layer of the
25
FUR DRESSING AND FUR DYEING
epidermis, or the ' rete malpighi.' Keratin is particularly
rich in sulphur, and is quite insoluble in cold water. Caustic
alkalies attack keratin-containing parts.
The collagens are the principal proteins of the skin, form-
ing largely the substance of the connective tissue fibres, and
consequently the framework of the skin. They are insoluble
in cold water, dilute acids and salt solutions, and are only
very slowly attacked by dilute alkalies. Dilute acids and
alkalies cause collagen to swell; concentrated acids, vegeta-
ble tanning materials, basic chrome or iron salts cause it
to shrink. By boiling with water, dilute acids or dilute
alkalies, collagen is split up into gelatin or glutin.
The mucines of the skin, intercellular material or coriin,
are soluble in dilute acids, in dilute solutions of alkalies and
of alkaline earths such as lime, and in 10% salt solution,
but insoluble in water, and in salt solutions of greater or less
concentration than 10%. On drying the skin, the mucines
cement the connective tissue fibres, causing the skin to be-
come stiff, horny and translucent. The mucines are also
constituents of the cells of the ' rete malpighi.' The solu-
bility of the mucines in dilute solutions of alkalies and of
alkaline earths causes the epidermis to be loosened from the
corium, when the skins are treated with such solutions for
some time.
When raw skins are boiled with water, the greater part
goes into solution, the residue consisting chiefly of the kera-
tins of the hair and epidermis cells. On cooling, the solu-
tion solidifies to a jelly of gelatine. It combines with both
acids and alkalies. A property of the skin which is of im-
portance in the tanning operation of fur-dressing, and a
quality which also characterizes gelatine, is the capacity to
absorb liquids and swell up, without changing chemically.
Raw pelts swell up easily in pure cold water, but much more
easily in solutions of dilute acids or dilute alkalies, only a
little of the skin material being dissolved. In stronger solu-
tions, the skins swell up less, while more of the skin sub-
26
STRUCTURE OF FUR
stance dissolves, and by prolonged action of strong acids
or alkalies, an almost complete solution of the skin is ob-
tained, without, however, any of the material decomposing.
With very strong alkalies or acids, the skin substance is
broken up into simpler compounds, such as various amines
and ammonia. The swelling action of acids or of alkalies in-
creases with the increase in concentration of the acid or
alkali, but only up to a certain point, after which further
increase in the strength of the acid or alkaline solution
causes a reduction in the swelling, and even produces
shrinkage. In the presence of neutral salts, like common
table salt, sodium chloride, the swelling action of acids, is
reduced, but the action of alkalies remains practically
unaffected.
When treated with the various chemicals, fur hair acts in
a manner quite similar to wool. If it be remembered that
certain classes of furs are derived from animals of the
sheep family, such furs as Persian lamb, krimmer, etc., it
becomes apparent why chemicals should affect furs in nearly
the same way as wool. The great majority of furs differ
from those of the sheep family., in .possessing much greater
resistance to the action of chemicals. The range is a
wide one however, and no exact criterion can be adopted.
As a general rule, the reactions are most marked with fur-
hair of a woolly nature, so this may be taken as a standard
of reference.
Acids have relatively little action on the hair, when
applied in dilute solutions. The scales of the cuticle or epi-
thelium are somewhat opened, the fibre becoming slightly
roughened thereby. Even at high temperatures, the hair is
quite resistant to the action of dilute acids. Concentrated
acids destroy the hair with the liberation or formation of
ammonia, hydrogen sulphide, and various amino acids.
When treated with dilute acids, the hair, especially if it is
of a very woolly nature, retains considerable quantities of
acid, this phenomenon being probably due to the fixation
27
FUR DRESSING AND FUR DYEING
of the acid by the basic groups in the hair. Nitric acid
produces a yellow coloration when applied in dilute solution
for a short time.- Sulphurous acid, the acid formed by the
burning of sulphur, has a bleaching action on the hair.
Alkalies attack the hair, even in dilute solutions, and by
longer action complete decomposition sets in, with forma-
tion of ammonia and amino-acids. Arrfmonium carbonate,
soap, and borax are practically harmless in their effect on
the hair. Sodium and potassium carbonates roughen the
hair on . prolonged action, even in dilute solutions. Cal-
cium hydroxide on continued action removes sulphur from
the hair, causing it to become brittle.
Salts of alkalies and alkaline earths do not affect the hair
at all. Salts of the heavy metals on the other hand, areTab-
"sorbe'd in appreciable quantities. From a dilute solution of
alum, aluminum hydroxide is absorbed by the hair, the
potassium sulphate remaining in solution. Similarly with
copper, iron, and chromium salts, the metal oxides are fixed
by the fibre.
28
CHAPTER III
FUR DRESSING
INTRODUCTORY AND HISTORICAL
;~"MJR DRESSING has a twofold purpose. First of
|H all, the putrefactive processes must be permanently
*- stopped, so that the skin may be preserved as such,
or worked up as some fur garment, without danger of de-
composition. Having taken measures to assure the en-
durance or relative permanency of the pelt, the prime con-
sideration is, of course, the appearance of the hair. The
hair must be so treated that all its inherent beauty is
brought out to the fullest extent. It must be made clean
and soft, and all the natural gloss must be preserved, and if
possible, enhanced.) The appearance of the leather is rela-
tively unimportant, since it is not seen after the furs are
made into garments. Thpre are, however, certain qualities
which it is essential for (the leather to possess after being
dressed, and these are, softness, lightness of weight, elasticity
or stretch, and a certain firmness or ' feel.' /In other words
the important considerations in fur dressing are the employ-
ment of means, and the exercise of care to preserve or even
improve those characteristics of the pelt which make it
valuable.)
The dressing of furs has many features in common with
the manufacture of leather, which is a kindred art. But
whereas in fur dressing the prime consideration is the ap-
pearance of the hair, and the leather is of secondary im-
portance, in the production of leather, the hair plays no part
at all, since it is entirely removed from the pelt. The fun-
damental points of resemblance between leather manu-
29
FUR DRESSING AND FUR DYEING
facture and fur dressing are in those processes and operations
which are concerned with the preservation of the leather,
and rendering it in the proper condition for use.
Both leather dressing and fur dressing have an origin
which may be regarded as identical, and which dates back to
the haziest periods of antiquity. In the course of satisfying
his needs, primitive man killed the animals about him, and
thus obtained his food. The killed animal also furnished
a skin, which after undergoing certain manipulations and
other treatments, could serve as a protective covering, orna-
ment, or defensive weapon. Since the skin in its natural
state was hardly fit for use because of its easy tendency to
putrefaction, it is evident that man had to find some means
of preventing this decay in a more or less permanent fashion,
and moreover had to treat the skin so that it would be suit-
able for use, by rendering it soft and flexible. The discovery
of means to accomplish these purposes was probably one of
the first great steps forward on the path of progress and
civilization.
There are evidences of the use of animal skins in the
earliest periods of antiquity, in fact it is a usage which may
be literally regarded as " old as the hills." One of the
earliest written records of the employment of the skins of
animals as garments, is in the Old Testament, where it
states, " Unto Adam and to his wife did the Lord God make
coats of skins, and clothed them.' j> Numerous other biblical
references indicate the use of animal skins for various pur-
poses, sometimes prepared as leather, with the hair removed.
Among the Egyptians tanning seems to have been a com-
mon occupation. The particularly attractive skins, like
those of the leopard or panther, were especially prized,
and were made up as furs for ornamental wear, rugs and
decorations. The less valuable skins were unhaired and
made into leather. Although the tanning or leather-pro-
ducing processes of the Egyptians are quite unknown,
numerous figures engraved in stone afford an indication to
30
FUR DRESSING INTRODUCTORY
some of the manipulatory operations, such as soaking the
skins, fleshing, softening with stones, stretching over a
three-legged wooden " horse," etc. Many articles, made of
leather, have been found in the various Egyptian sar-
cophagi, and all are in a splendid state of preservation,
after forty centuries, thereby indicating a very efficient
method of dressing animal skins. Likewise, the presence
in the museums of various articles, leather and fur, of As-
syrian, Phoenician and Persian origin, tends to show that
these peoples also possessed a considerable degree of profi-
ciency in tanning. Frequent references in the Greek litera-
ture show that leopard and lion skins were worn as war
cloaks, and they undoubtedly were properly made. In the
Iliad is described an operation for the preparation of skins
for use as garments, and the method seems to be a sort of
chamois dressing.
The first method of tanning skins was, in all probability,
that of rubbing into the skins various fatty materials found
close at hand, such as parts of the animal, fat, brains, milk,
excrement, etc., such an operation constituting the basis of
what is now known as the chamois dressing. One of the
reasons for believing that it was the first process to be used
by primitive man, is the fact that certain undeveloped tribes
and races of the present day still dress skins by it. The
American Indians, even to this day prepare skins by rubbing
in, on the flesh side, the brains of the animals which furnished
the skins. The Eskimos dress skins by rubbing in animal
fats or fish-oil, and subsequently softening and stretching
the skins with their teeth in place of, or for want of other
implements. Usually, however, variously shaped stones
or bones of animals are used to obtain the proper degree of
softness and flexibility. It is true, too, that some of the
skins dressed in this primitive fashion can scarcely be ex-
celled by any dressed with more modern processes and tan-
ning methods.
The next step forward in the preparation of animal skins
31
FUR DRESSING AND FUR DYEING
for use was undoubtedly the utilization of substances found
in the earth. Common salt, sodium chloride, was the most
universally used substance of mineral origin, just as it is
today. Our prehistoric ancestors eventually discovered the
preservative action of salt, and applied it to skins. While it
was effective, it was not sufficiently permanent, so another
mineral, also of very common and wide occurrence was used
in combination with the salt, and the result proved quite
satisfactory. This second common mineral was alum. The
use of alum, which is the basis of numerous tanning pro-
cesses to this day, seems to have been quite a popular method
of ancient times. Artemidorus, a Greco-Roman writer,
mentions the use of alum by the Greeks, and the Romans
are known to have prepared a soft, flexible leather called
aluta (alum leather), by using it. In view of the fact that
Egypt had extensive deposits of alum, it is believed that the
alum-salt process was employed also by the Egyptians in
the preparation of leather. However, the evidence on this
point is not conclusive.
One of the most important methods of producing leather,
either as such or on furs, was with the aid of certain vegeta-
ble extracts, known as the tannins, from which the process
of tanning gets its name. The discovery of the value of
these materials for converting the decaying raw skin into
a leather which could be preserved for an almost indefinite
length of time, and which was flexible and soft as desired,
was of far-reaching importance. For it is only in very recent
times that these tannins have been superseded in part by
new tanning substances whose use is simpler and more
time-saving. Yet there are unmistakable indications that
the tannins were employed for tanning at a period which
reaches back to the dawn of history. Although it is scarcely
probable that the people who used these materials could
have known of the existence or the nature of the particular
substances in the vegetable extracts which actually effect
the tanning action, experience taught them to employ these
32
FUR DRESSING INTRODUCTORY
plants which possessed the highest content of active ingredi-
ents, and which, consequently, were most effective in use.
Tychios, of Boetius, a Greek supposed to have lived about
900 B.C. and mentioned in the Iliad, is considered the oldest
known tanner, and was regarded by Pliny, a Roman writer,
as the discoverer of tanning, and of the use of the various
vegetable tanning materials. At any rate, the Greeks used
the leaves of a so-called tanning- tree, which was probably
the sumach. The Egyptians worked with the acacia, while
the Romans used as tanning materials the barks of the pine,
alder and pomegranate trees, also nut-galls, sumach and
acorns. The Romans were quick to employ methods used by
the peoples whom they conquered, and it is in this way that
they learned the use of many of the plants mentioned, for
tanning purposes.
Many other ancient peoples had various processes of tan-
ning, the methods probably differing in each country. Thus
the Chinese, Syrians, and much later, the Moors, were each
know r n for proficiency in a certain class of leather tanning.
It has been said that in general, even up to modern times,
tanning with nut-galls was the characteristic method of the
Orient ; with oak- tan, that of the Occident, while the use of
alum is regarded as the method peculiar to the Saracens.
In prehistoric times and the early centuries of civilization,
skins or pelts were prepared for use by the individual, the
work usually being done by the housewife and daughters,
while the masculine members of the family were engaged in
hunting the animals and obtaining the skins. At a later
period, when people had advanced to the point where they
lived in cities, the preparing or dressing of skins became cen-
tered in the hands of a comparatively small number of
people, and thus the work took on the aspects of a trade.
The workers in fur were at first the same people who made
leather out of the skin, for the two kinds of work were very
closely associated. During the period of the Roman su-
premacy, historical records show that the furriers, who did
33
FUR DRESSING AND FUR DYEING
all the work connected with furs, from purchasing the raw
skins, dressing them, making them into garments, to selling
the latter, were organized into associations together with
the leather workers. After the fall of the Roman empire,
and throughout the centuries known as the Dark Ages, all
traces of the furriers seem to have been lost, but in the be-
ginning of the Renaissance period in the fourteenth and
fifteenth centuries, we again find records of the furriers, who
were now all members of the furriers' guilds, also in associa-
tion with the leather workers. As formerly, all the work
connected with the production of fur apparel from the raw
furs, was done by the master furrier and his apprentices.
The methods and the implements used, were essentially the
same as in Roman times, and in fact, up to a very recent
period there was very little change in either.
With the advent of the great industrial era at the begin-
ning of the nineteenth century, the guild system became
ineffective, but the furriers continued their work as here-
tofore. Up to about the middle of the nineteenth century,
the furrier continued to be the only factor of any importance
in the fur trade. There was no need for speed in his work,
for the demands of the trade were not so urgent. The fact
that the dressing of furs often occupied two to four weeks
was no deterring factor in his business. However, with the
great expansion of the fur trade about this time, it became
impossible for the individual furrier to do everything him-
self, and keep up with the requirements of his customers.
Specialization commenced, and establishments were set up
solely for fur dressing. The traditional time- and labor-
consuming processes were still used, but the efficiency of
work on a large scale enabled the fur dressers successfully
to fill their orders. But the fur trade continued to grow
by leaps and bounds, and very soon the fur dressers were no
longer able to meet the demands of the trade. It was then
that the science of chemistry came to the aid of the fur
dresser, and helped him meet the exigency. By devising
34
FUR DRESSING INTRODUCTORY
dressing processes which were cheap and efficient, and which
only required several hours, or at the most one or two days,
as compared with as many weeks, the chemist brought the
fur dresser out of his dilemma. And with the adoption of
mechanical time- and labor-saving devices, the fur dressing
industry has made wonderful progress.
35
CHAPTER IV
FUR DRESSING
PRELIMINARY OPERATIONS
THE fur dresser receives the skins in one of two
shapes, flat or cased, depending on the manner in
which they were removed from the animal. Flat
skins, as for example, beaver, are obtained by cutting- on the
"under side of the animal from the root of the tail to the
chin, and along the inner side of the legs from the foot to
the first cut. The skins are either fastened to boards or at-
tached to wooden hoops slightly larger than the skins, so
as to stretch them, and are then carefully dried, avoiding
direct sunshine or artificial heat, as it is very easy to over-
heat the skins and thereby ruin them. The great majority
of skins, however, are cased. The pelts are cut on the
under side of the tail, and along the hind legs across the
body, the skin being then removed by pulling it over-4he
head off the body like a glove, trimming carefully about4he_
ears and nose. The skin is thus obtained inside out. and
is drawn over a stretching board or wire stretcher of suitable
shape and dimensions, so as to allow the skin to dry with-
out wrinkling. The pelts, after drying in a dry, airy place,
are removed from the stretchers and. are ready for the mar-
ket. With some furs, as foxes, the skins are turned hair-side
out while still somewhat moist, and then put on the stretcher
again till fully dried. In most cases, however, skins are sold
flesh-side out. Throughout the various dressing opera-
tions cased skins are kept intact, being turned flesh-side out
or hair-side out according as the processes are directed to
the respective sides. The pelts are only cut open if they
PRELIMINARY OPERATIONS
have to be dyed, or after the manufacturer receives them,
when they have to be worked into manufactured garments.
A distinction which is made by fur dressers and dyers, and
also by the fur trade in general, divides furs into those de-
rived from domestic animals, particularly the various kinds
of sheep, including also the goat species, and those obtained
from other animals by trapping. In fact, at one time, and
to a certain extent even to-day, dressers were divided into
two groups based on this distinction, one class dealing only
with furs obtained from the sheep family, and the other
working with other kinds of furs. This differentiation is not
a simple arbitrary one, but has a rational justification. As
mentioned before, the manner and habit of living of the ani-
mal are important factors in determining the nature and
constitution of its skin, both leather and hair. The structure
of the body being dependent primarily upon the nature of
the food absorbed by the animal, it is only natural that
herbivorous or vegetable-eating animals such as sheep and
goats, should possess fur of a different sort from that of the
carnivorous or meat-eating animals, such as the majority
of fur-bearers are. It also seems clear that furs differing in
their character and constitution should require somewhat
different treatments, and accordingly the methods are modi-
fied when furs like lambs or goats are dressed. To a great
extent, however, the fundamental operations are similar for
all furs, regardless of nature or origin, and these will be
discussed briefly.
Inasmuch as the first great purpose of fur dressing is to
render the skins more or less permanently immune from the
processes of decay, it is necessary to prepare the pelts so
as to be most fit to receive the preserving treatment. The
skins as they are delivered to the fur dresser have, in the
majority of cases, been stretched and dried to preserve them
temporarily, while in some instances, especially with the
larger furs like bears and seals, they are salted and kept
moist. The flesh-side of the pelt still has considerable fleshy
37
FUR DRESSING AND FUR DYEING
and fatty tissues adhering to it, and the hair is generally
soiled and occasionally blood-stained. In order to get ffieT'
pelts into such a condition that they can be worked and
manipulated, they first have to be made soft and flexible.
Very greasy skins are scraped raw in
order to remove as much as possible
of the attached fat, the operation^ being
known as beaming or scraping./ The
typical beam, shown in Fig. 3, consists
of a sloping table usually made of some
hard wood, and placed at an angle of
about 45. It is generally flat, al-
though in some instances convex beams
are also used, about a yard long, 8 to 10 inches wide, and
firmly supported at the upper end. The skin is placed on
the beam, flesh-side up, and is scraped with a two-handled
knife (Fig. 4), always in a downward direction.
FIG. 3. BEAM,
Shaving Knife.
FIG. 4. KNIVES USED IN FUR DRESSING.
The first step in softening the skins is to get them thor-
oughly moistened, and this is variously done, depending
on the nature of the skin. Lambs, for example, require the
gentlest means of wetting them, while rabbits can stand
38
PRELIMINARY OPERATIONS
soaking in water for several days. The manner and duration
of moistening must be adjusted to the character of the pelt.
For the putrefactive processes which were stopped by
stretching and drying the skins, cqntinue as soon as the
pelt is again moistened. The progress of decay causes the
evolution of certain gases, the simplest of which is am-
monia, and eventually, if permitted to proceed, brings about
the complete disintegration of the skin tissue. It has been
found that a certain amount of gas formation is necessary to
loosen up the fibres in order to get the best quality of leather
after tanning. This process must be interrupted at the
proper time and not allowed to proceed too far.
Skins which have been preserved fresh by salting, require
only a comparatively short time (about 2 hours) to become
softened by soaking in clean, soft water. Most dried skins
need a longer treatment before they are sufficiently flexible.
The addition of certain substances to the water facilitates
and accelerates the softening. In some instances salt water
is used for soaking the pelts, the preservative action of the
salt tending to prevent any loosening of the hair. A solu-
tion of \% borax is very effective in rendering the skins soft,
and clean as well. Borax has an exceedingly mild alkaline
action, and causes a slight swelling of the skin tissue, which
then absorbs the water more readily. Being also preserva-
tive and antiseptic, borax tends to prevent decomposition of
the skin tissue. Another chemical of a different nature,
but equally effective is formic acid, used in the proportion
of 1.5-2.5 parts per 1000 parts of water. Formic acid also
induces a swelling of the skin, the pelts being soaked in a
short time, and the antiseptic action of the acid obviates
the possibility of the hair becoming loose. The water used
should be fresh and clean, and the soaking must be stopped
as soon as the skins have become sou ana dexibl&. SMB6-
times the skins are allowed to soak overnight in water, while
in other cases, the pelts are just moistened by dipping in
water until thoroughly wet, and then laying them in a pile
39
FUR DRESSING AND FUR DYEING
for several hours, or overnight. Another method which is
practised with certain types of skins is the use of wet saw-
dust or of sawdust moistened with salt water. The fur skins,
are either embedded in the sawdust or drummed- witilujt_
for several hours, or until sufficient moisture has .bejerL ab^__
sorted to render them flexible. By this means there is no
danger of the skins being over-soaked, or of the hair being
loosened. WJtanJheLgkins have been properly wetted, they
are drawn with the flesh-side across the edge of a dull
knife-blade, in order to help loosen the texture of the skin.
They are then put into a tramping machine and worked
until completely softened. In the case of large or heavy
skins, the moistened pelts are worked on the beam with a
dull beaming knife to impart thorough softness and
flexibility.
The pelts are then cleaned with particular reference to
the hair. With some furs this is accomplished simply by
drumming for several hours with dry sawdust^ whereby the
oil and dirt' are removed from the hair, and the hair is then
"freed from the sawdust by caging. Otfier skins are washed^)
being passed through a weak soap solution for a short time,
the dirty spots being brushed. Occasionally an extract of
soap-bark is used in place of the soap, being even more effec-
tive. The cleansed skins are then thoroughly rinsed to re-
move any of the cleaning material, which would affect the
gloss of the hair if allowed to remain on the skins. Then in
order to eliminate as much as possible of the water in the
skins, they are hydro-extracted, a centrifugal machine of
the type shown in Fig. 5 being used. The basis of its action
depends on the utilization of the principle of centrifugal
force. The machine consists essentially of a perforated
metal basket generally made of copper, capable of being
rotated at a high speed. Surrounding the basket is an iron
framework, polished or enamelled on the inside. The wet
skins are placed in the rotating basket, fur side toward the
perforations, and the water which is thrown off from the
40
PRELIMINARY OPERATIONS
skins passes through the little holes, and is caught up on the
walls of the outside frame, from where it is led off through
suitable ducts. The centrifugal device is properly equipped
with balancing and regulating attachments, as well as with
a brake. The power may be applied by the over-drive or
the under-drive as is most desirable in the particular case.
FIG. 5. CENTRIFUGAL MACHINE.
(Fletcher Works, Inc., Philadelphia)
The inner surface of the basket can also be enamelled or
otherwise made resistant to the action of acids or other
chemicals.
When the skin is removed from the animal, as much as
possible of the adhering fat and flesh is scraped off, but in
spite of this, and in spite of subsequent beaming by the
fur dresser, there is always a thin layer of flesh and fatty
material remaining and this must be removed so as to ex-
pose the corium, enabling the efficient action of the chemi-
cals used in the tanning processes. The process of removing
this undesirable layer from the flesh-side is known asjflesh-
ingx It is a rather delicate operation, requiring considerable
experience and dexterity on the part of the worker, for it is
exceedingly easy to cut into the skin and damage the fur.
41
FUR DRESSING AND FUR DYEING
A fleshing knife of the type commonly used is shown in
Fig. 6. It consists of a sharp blade fastened at a slight angle
from the vertical, with the cutting edge away from the
workman, who straddles the bench, and by drawing the
skins back and forth across the edge of the blade, removes
all flesh and fat, leaving the corium free and clean. Large
skins cannot conveniently be fleshed in this fashion. They
FIG. 6. FLESHING KNIFE ON BENCH.
are placed on the beam, and fleshed with a fleshing or skiv-
ing knife similar to the beaming knife, but consisting of a
slightly curved, sharp two-edged blade having handles at
both ends. Frequent attempts have been made to use suit-
able machines to do this work. A type of machine which has
met with considerable success is depicted in Fig. 7. It is
fashioned after the models used for the fleshing of hides for
leather manufacture, and has special adjustments and regu-
lating devices which afford protection for the hair part of
the fur. From time to time other fleshing machines are put
on the market, yet none of them seems to enjoy any great
popularity, for fleshing is still largely a manual operation.
With some classes of pelts, fleshing presents some diffi-
42
PRELIMINARY OPERATIONS
culties, and chemical means have to be resorted to in order
to loosen the flesh sufficiently to enable proper fleshing. In
the case of large furs like bears, leopards, and the like, which
while of no great importance in the fur trade, are occasion-
ally met by the fur dresser, the skins after being soaked,
FIG. 7. FLESHING MACHINE.
(Turner Tanning Machinery Co., Peabody, Mass.)
and washed with soap-water, are partially dried; then the
flesh-side is treated with technical butter or oil, which is
tramped in. A mixture of salt water and bran is then ap-
plied to the skins, thereby causing a swelling action to set
43
FUR DRESSING AND FUR DYEING
in, and the flesh becomes loosened, and is easily removed by
fleshing on the beam. Seals receive a special treatment
which makes them soft, and gives them greater stretch
after they are tanned. A paste made by mixing a very dilute
solution of caustic soda with an inert substance like French
chalk, china clay, etc., is applied to the corium after the
skins have been fleshed, then the pelts are folded up, and
allowed to lie for several hours. They are then entered
into a dilute solution of calcium chloride and left overnight.
After being washed in a paddle or drum, first with fresh
water, and then in water containing lactic or formic acid to
remove the lime, the skins are ready for tanning.
44
CHAPTER V
FUR DRESSING
TANNING METHODS
yl FTER the pelts have gone through the preliminary
/-\ operations of softening, washing and fleshing, they
>* -^- are ready to receive the treatment which will con-
vert the easily decomposing skin into leather x>f more or less
permanency, depending on the method used/
During the past century, considerable study has been
made both by scientific and technical people, of the prob-
lem of leather formation. Numerous theories as to the na-
ture of the process have been evolved, but even to this day,
no satisfactory explanation has been given which would
account for all the facts as they are now known, so the
matter is still a subject of considerable controversy. Proc-
ter, who is one of the leading authorities on leather today
discusses the development of the tanning theories as
follows :
" The cause of the horny nature of dried skin is that the
gelatinous and swollen fibres of which it is composed not
merely stiffen on drying but adhere to a homogeneous mass,
as is evidenced by its translucence. If in some way we can
prevent the adhesion of the fibres while drying we shall
have made a step in the desired direction, and this will be
the more effective the more perfectly we have split the fibre-
bundles into their constituent fine fibrils, and removed the
substance which cements them. The separation of the
fibres can be partially attained by purely mechanical means.
45
FUR DRESSING AND FUR DYEING
. . . Knapp, to whom we owe our first intelligible theories
of the tanning process, showed that by physical means the
separation and drying of the fibres could be so far
effected as to produce without any tanning agent a sub-
stance with all the outward characteristics of leather,
although on soaking it returned completely to the raw
hide state. He soaked the prepared pelt in absolute
alcohol, which penetrated between, and separated the
fibres and at the same time dried them by its strong affinity
for water. More recently, Meunier has obtained a similar
result by the use of a concentrated solution of potassium
carbonate which is even more strongly dehydrating.
" Knapp made a further step by adding to his alcohol a
small quantity of stearic acid which, as the alcohol evapo-
rated, left a thin fatty covering on the fibres which com-
pletely prevented their adhesion, and reduced their tendency
to absorb water ; and he so produced a very soft and white
leather. Somewhat similar are the principles of the many
primitive methods which apply fatty and albuminous mat-
ters, grease, butter, milk, or brains to the wet skin, and by
mechanical kneading and stretching, aided by capillarity,
work these matters in between the fibres as the water evapo-
rates. Such methods are still used, and enter into many
processes in which other tanning agents are also employed.
" Building upon these facts, Prof. Knapp advanced the
theory that the effect of all tanning processes was not to
cause a change in the fibres themselves, chemical or other-
wise, but merely to isolate and coat them with water-re-
sisting materials which prevented their subsequent swelling
and adhesion. True as this theory undoubtedly is in many
cases, it can hardly be accepted as the whole truth, and it
seems incontestable that frequently the fibres themselves
undergo actual chemical changes which render them in-
soluble and nonadhesive.
" Before Knapp's work, the prevalent theory, at least as
regards vegetable tannage, had been a chemical one, started
46
TANNING METHODS
by Sir Humphrey Davy. If a solution of gelatine be mixed
in proper proportion with one of tannin, both unite to form
a voluminous curdy precipitate; and, according to Davy's
ideas, this was amorphous leather. Against this, it was
urged that even the supposed ' tannate of gelatine ' itself
could not be a true chemical compound, since the propor-
tions of its constituents were considerably varied by changes
in the strength of the solutions, or by washing the precipi-
tate with hot water; and further, that in chemical com-
pounds, the form was changed, and no trace of the original
constituents appeared in the compound; while in leather
apart from some change of color and properties, the original
fibrous structure remained unaltered.
" This reasoning appears much less conclusive now than
it did in Knapp's day. Against the last objection guncot-
ton may be quoted as an instance of profound chemical
change with no alteration in outside appearance; and it
is recognized that, especially among complex organic sub-
stances, chemical reactions are rarely complete, but that
stable positions are reached, so-called ' equilibria/ in which
the proportion of changed and unchanged substance is de-
pendent on concentration or other conditions; and that
therefore such a precipitate might well be a mixture of gela-
tine with a true gelatine tannate from which further por-
tions of tannin might be dissociated by water.
" With the clearing up of old difficulties, however, the
conflict between chemical and physical theories has, as
is usually the case, merely passed into a new phase. Years
ago, it was shown by Linder and Picton and others, that
liquids could be obtained which were not really solutions of
ions or molecules, but merely suspensions like that of clay
in water, or butter-fat in milk; but so finely divided as to
appear clear and transparent, and pass through filters like
true solutions. Later, by means of the ultra-microscope
their discrete particles have actually been made visible, each
of them consisting of many molecules of the suspended
47
FUR DRESSING AND FUR DYEING
substance. Nevertheless, these particles have many mo-
lecular properties, possessing plus or minus electrical
charges; behaving like large ions under the influence of an
electrical current ; and mutually precipitating and neutraliz-
ing each other when positive and negative are brought to-
gether. Such solutions are called l colloid/ and those of
gelatine and tannin are of the class, so that it is now often
said that the precipitation of gelatine by tannin, and the
fixation of tannin by gelatinous fibre are merely ' colloidal '
and i physical/ and not ' chemical ' phenomena. Admitting
the facts, the question still arises whether the distinction
between chemical and physical is not here one without a
difference; and whether between the purely ionized dilute
solution of a salt and the coarsely granular clay suspension
there is any point where a definite line of demarcation can
be drawn. The writer inclines to the view that there is
not; and that ionic and colloidal combinations are extreme
cases of the same laws, both physical, and both chemical."
There are several methods which are used in tanning
furs, each having its peculiar characteristics and qualities,
and possessing individual advantages and disadvantages.
In order to be able to judge the merits of the various proc-
esses, it is necessary to have a criterion which can serve
as a basis of reference. Fahrion, a recognized authority
and investigator in this field, gives a definition of leather
which is usually accepted as a standard for comparison. He
says: "Leather is animal skin, which on soaking in water
and subsequent drying does not become hard and tinny, but
remains soft and flexible ; which does not decay in the pres-
ence of cold water ; and which does not yield any gelatine on
boiling with water." While the requirements set forth in
this statement are essential for leather, and a compliance
with them would also be desirable for tanned furs, a some-
what less rigorous standard of conditions to fulfil is satis-
factory for the general needs and purposes of furs. The
chief qualities which tanned furs must possess, with par-
48
TANNING METHODS
ticular reference to the leather side of the pelt, are reten-
tion of softness and flexibility after being moistened by the
furrier for manufacturing purposes, and subsequent drying ;
and freedom from a tendency to decay during this opera-
tion and thereafter. If the furs are to be dyed, the effect
of the dyeing must also "Be considered, and the tanning must
be such as to enable the dyed furs to possess the above
qualities.
/The most important tanning processes employed for furs
are the following:
1. Salt-acid tan, or pickle.
2. Mineral tans.
3. Chamois tan.
4. Formaldehyde and similar tans.
5. Combination tans.
6~ Vegetable tan.
1
. SALT-ACID TAN, OR PICKLE
This is one of the most extensively used methods for tan-
ning furs, and is also very cheap and easily applied. A
typical formula for this tan is the following: A solution of
salt is prepared containing about 10% of common salt,
sodium chloride, and to this is added ^-f ounce of
sulphuric acid for each gallon of tanning liquor. The
proportions may be varied within certain limits, but
the figures here given are those which have proven
successful in practise. The solution should be made
in a wooden or earthenware container, free from any
metal, as it would be attacked by the acid. The liquor
is then applied to the flesh-side of the fleshed skins
by means of a brush, making sure to touch all parts
of the pelt. They are then placed in a pile and allowed to
remain thus until tanned, an operation which occupies a
"""time ranging from a few hours to two or three days de-
pending on the thickness of the skins. When the corium
49
FUR DRESSING AND FUR DYEING
has lost its translucence and has become of a milky-white-
color throughout the entire thickness of the skin, as can
be seen by viewing a cross-section, the skinjriay be con-
sidered tanned. In some instances, where the hair of the
fur can stand immersion without injury, the skins are
entered into the pickling solution and allowed to remain
for 12 to 24 hours, which is generally a sufficient time to
tan them in this manner.
The acid of the pickle causes the skin to swell, the salt
then penetrating between the fibres of the corium, and at
the same time reducing the swelling of the skin. The acid
also neutralizes the alkaline products of decomposition
which may form, while the salt acts as a deterrent to the
progress of the putrefactive processes. When the skin is
dried after tanning, and stretched and finished, a soft white
leather is obtained which is permanent as long as it is kept
dry. It is the salt which causes the fibres of the skin to be
completely differentiated and thus prevents their adhesion.
It is interesting to note that other acids besides sulphuric
can be used for the pickle, organic as well as mineral,
formic acid in \% solution being especially effective and
giving excellent results, but is more expensive than the
mineral acid. A method, which in principle is identical
with the pickle, but carried out in an entirely different
manner, is the lactic acid fermentation process, or " Schrot-
beize " as it is called in German. The procedure is in
general as follows: " The fleshed skins are placed on tables,
flesh-side up, and covered with a layer of bruised barley-
grains, or a mixture of 3 parts of wheat bran and 2 parts of
rye flour. Then the head, tail and legs are turned inward,
and the skins rolled up in little cushions, hair-side out, and
placed in a vat. When this is filled with the skins a solu-
tion of common salt is poured over them, and they are
allowed to remain thus in a moderately cool place for 24
hours. After this time, the skins are carefully unrolled, so
as not to remove any of the adhering solid materials, and
50
TANNING METHODS
turning the skins hair-side inward, they are laid flat to-
gether in paies and placed in an empty vat. After another
24 hours they are again unpacked and replaced in another
vat, care being taken each time to keep all the solid par-
ticles adhering to the flesh-side. This operation is con-
tinued and repeated until the skins are properly tanned,
which takes from 10 to 14 days, depending on the weather
and the temperature. The skins are then removed, rinsed
free of the tanning substances, pressed, dried and finished."
A somewhat modified form of this process is the so-called
Russian tan, which is usually done in the following man-
ner: 5 parts of bruised barley grains are mixed with ten
parts of luke-warm water in a vat, which is then covered
up. A small quantity of brewers' yeast is also added to aid
in the fermentation. As soon as the mixture develops a
slight heat, one part of fresh whey is added, and the fleshed
skins entered into the tanning liquor in which they remain
for about 12 hours. They are then tramped in the mixture
so as to effect greater penetration, and left until the tanning
process is complete. Whey is the milk fluid left after the
casein and most of the fat have been removed from the
milk by coagulation, and consists practically of a solution
of all the milk-sugar or lactose, and the lactic acid of the
milk, together with a small percentage of mineral salts,
and a slight amount of fat. By fermentation, the milk-
sugar is converted into lactic acid, which helps to effect
the tan by swelling the skin.
The effectiveness of the fermentation processes depends
to a considerable degree on the action of certain bacteria
and yeasts. Bacteria are one-celled organisms belonging to
the vegetable kingdom, and some are so small as to be
scarcely visible under a microscope, while some indeed can-
not be seen by any means, their existence being inferred
from their effects. As they vary in size, bacteria also vary
in shape, some being spherical, others in the form of long,
thin rods, while still others are of a spiral shape; another
51
FUR DRESSING AND FUR DYEING
common form is the dumb-bell shaped bacterium. Some
types are provided with what are known as flagella, which
resemble fine hairs attached to the body of the organism,
and which enable it to move about actively in liquids. The
food of bacteria is always in liquid form, as only in this
condition can it be absorbed. However, some kinds of bac-
teria attack solid substances from which they obtain their
nourishment, but this is done in an indirect way, by secret-
ing certain fluids known as enzymes, which dissolve or
digest the material and convert it into a form that can
easily be absorbed by the bacteria. The enzymes are non-
living chemical substances, which possess the peculiar prop-
erty of bringing about the chemical change of an almost in-
definite amount of material upon which they act, without
themselves being in any way changed. Yeasts also act in
a manner similar to the bacteria in causing various chemi-
cal changes, particularly inducing fomentations. In the
simple " Schrot-beize," the starch contained in the bran or
barley grains is first converted to a soluble sugar by means
of enzymes secreted by the bacteria which are always
present. This sugar then undergoes an acid fermentation,
with the formation of lactic and acetic acids, due in this
case to organisms known as the bacterium fur juris A and
B. The action of the Russian tan is similar, but quicker.
In this case, the sugar is already present in soluble form,
and the yeast cells cause its fermentation with the produc-
tion of lactic acid. In both cases, the acids as they form
swell and loosen up the skin fibres slowly, the salt penetrat-
ing between them, and keeping them separated on drying.
Both methods give results which are equally good, but by
the Russian tan the skins acquire a disagreeable odor,
which makes this method of dressing objectionable.
The lactic acid fermentation processes have an advan-
tage over the pickle, in that the slow formation of weak
organic acids with their gradual action produce a softer
leather, with a gentler ' feel,' the presence of the flour and
52
TANNING METHODS
the grains of the tan, aside from their tanning action, con-
tributing to the fullness and softness of the leather. There
is also less likelihood of the leather being subsequently af-
fected by the presence of the acid in it, as lactic and acetic
acids are much less injurious than sulphuric acid to leather.
These disadvantages of the pickle can to a large degree,
be overcome without any great difficulty. On the other
hand, the matter of the length of time of the tanning
process, shows the acid pickle at a great advantage, and
so, especially for furs other than those obtained from sheep
and goats, the pickle is in most cases used as the principle
method of tanning. In Austria, Russia, and to a certain
extent in Germany also, the " Schrot-beize " is still con-
siderably employed, chiefly for dressing sheep and lamb
skins. The dressing of the various kinds of Persian lambs,
caraculs, astrachans, etc., in the native center of the in-
dustry in Buchara and surrounding districts, is also a
" Schrot-beize," barley, rice flour or rye flour, and salt water
being used to prepare the skins, the manipulations being
essentially the same as those described above, although
carried out in cruder and more primitive fashion.
2. MINERAL TANS
The basis of the tanning of furs by means of solutions
of mineral compounds is the fact that the basic salts of
certain metals are capable of producing leather. It has
been found that compounds of aluminum such as alum or
aluminum sulphate, or any other soluble neutral salt of
aluminum, possess tanning powers. Other metals which
are capable of forming salts of the same type are also en-
dowed with the quality of converting skin to leather under
suitable conditions, chromium and iron being the most im-
portant metals in this connection. Chemically these
metals all belong to the same group, and have properties
which are very similar in many respects, the characteris-
53
FUR DRESSING AND FUR DYEING
tic of most importance for tanning purposes being the
quality of forming soluble basic salts by the addition of
alkalies or alkaline carbonates to solutions of their neutral
salts, or in certain instances simply by the action of water
upon these neutral salts. By neutral salts are meant those
in which the metallic content is combined with the nor-
mal proportion of acid ; while basic salts are those in which
the acidic portion is present in less than the normal ratio,
being partially replaced by a hydroxide group. When the
acid part of the salt has been entirely replaced in this way.
the compound is called a hydroxide or hydrate of the metal.
Between the neutral salt and the hydroxide several different
basic salts are possible, some being soluble, while others are
insoluble. If into a solution containing a basic salt of either
aluminum, iron or chromium a skin be entered, a part.nl-
the basic salt will be precipitated on it in insoluble form:.
Inasmuch as neutral salts of these metals when dissolved in
water split up to a small degree, into free acid and soluble
basic salt, a skin immersed in such a solution will also ab-
sorb the basic salt in an insoluble form. Upon these facts
in general, depends the action of the mineral tans used in
tanning furs.
A. Alum Tan
The alum tan is one of the oldest methods of producing
leather, being employed by the Romans about two thou-
sand years ago, and it is believed, by the Egyptians at a
much earlier period. Its extensive use in Europe, however,
dates from the time of the conquest of Spain by the Moors,
who introduced the process.
At the present time, rabbits and moles are tanned by this
process, as are also at times other furs such as muskrats,
squirrels, sables, martens, etc., when a better tan is desired
than that produced by the pickle. Ordinary alum, which is
a double sulphate of aluminum and potassium, and alumi-
num sulphate are the chief compounds used for this tan.
54
TANNING METHODS
In recent years, the aluminum sulphate has to a consider-
able degree replaced the alum for tanning, inasmuch as it
can be cheaply obtained in a sufficiently pure form, and
contains about one and one-half times as much active
aluminum compound as does alum.
While the aluminum salt can be used alone for tanning,
it produces a stiff, imperfect leather, so salt is always
added. The ratio of the salt to the aluminum sulphate or
alum can vary within rather wide limits, the mixtures used
in practise ranging from one part of salt to four parts of
the aluminum compound, up to equal parts of both, or even
in some formulas, a greater proportion of salt than of the
other constituent. Ratios which are most common are four
of alum to three of salt, or two of alum to one of salt.
When aluminum sulphate is dissolved in water, a small
part of it splits up into a soluble basic salt and an equiva-
lent amount of free acid. The reaction may be shown as
follows :
A1 2 (S0 4 ) 8 + 2H 2 = A1 2 (SO,) 2 (OH) 2 + H 2 S0 4
aluminum water basic aluminum sulphuric
sulphate sulphate acid
When a skin is entered into such a solution, the free acid
is absorbed, causing a swelling of the pelt. While this is
taking place, a further quantity of the neutral aluminum
salt splits up into more basic salt and free acid. At the
same time the basic aluminum sulphate is also taken up
l>y the skin, probably attaching itself to some of the acidic
groups contained in the skin substance, in a manner analo-
gous to the combination of the acid with the basic groups
of the skin substance. A point is reached, however, when
the skin is no longer able to take up more of the basic salt,
for the presence of the acid undoubtedly acts as a deterrent.
The skin, if dried after such a treatment contains a small
amount of aluminum, which is insufficient to tan the pelt
properly, and as a result this comes out in an undesirable
55
FUR DRESSING AND FUR DYEING
and quite useless condition. If to the solution of the alumi-
num sulphate salt is added, a different result is obtained.
To a certain extent the salt acts here as in the pickle. The
skin on absorbing the free acid of the solution naturally
swells, but the salt reduces this swelling, and at the same
time, by penetrating between the fibres and dehydrating
them, produces a leather as in the pickle. In addition, the
presence of the salt enables a greater amount of basic
aluminum sulphate to be formed, and thus a greater quan-
tity is taken up by the skin. On drying and stretching
after such a treatment, a soft, flexible and stretchable
leather is obtained.
The number of formulas for tanning furs by this process
is legion, the principle being the same in every instance,
and mixtures of salt and alum or aluminum sulphate form
the basis of the various tans. Following are a few
typical formulas, which have been found to be of practical
value :
A solution is prepared by dissolving 7.5 Ibs. of alum and
3 Ibs. of common salt in 20 gallons of water. When cool,
the clean, fleshed skins are entered, being paddled or
drummed for a short time and then allowed to remain
until tanned. By this method the hair also takes up some
of the alum, and if the skins are to be dyed, unevenness
may result. In order to avoid this, the tanning may be
effected by brushing a stronger solution on the pelt. A
mixture of 4 Ibs. of alum and 3 Ibs. of salt, dissolved in 8 gal-
lons of water, and made into a paste by the addition of 4
Ibs. of flour, is applied to the flesh-side of the skins. These
are then placed in pairs, flesh-side together, and allowed
to remain in a pile until tanned. Sometimes a second ap-
plication is given. The flour may be omitted, but it serves
to cause the tanning mixture to adhere better to the skins.
Still another method is the following: Into the flesh of
the moist, fleshed skins is rubbed a mixture of two parts
of dry powdered alum with one part of salt. After allowing
56
TANNING METHODS
time for it to be absorbed, another application is given, rub-
bing in well, and especially treating the thick parts. The
pelts are then folded up, or rolled together, flesh-side in, and
placed in a vat or tub, which is covered up to prevent dry-
ing. They are left so until tanned, as shown by examina-
tion and test. They are then rinsed, hydro-extracted and
dried, and after stretching and finishing, a soft, white, pli-
able leather is obtained.
B. Chrome Tan
By using chrome alum instead of ordinary alum, to-
gether with salt, skins can be tanned, but the leather formed
is not altogether satisfactory. The basic principle here is
the same as in the alum tan, depending on the formation
of soluble basic chrome sulphates in the solution of a neu-
tral sulphate. The method employed at the present time,
the so-called one-bath process as distinct from the two-bath
process, which cannot be applied for tanning furs, involves
the production of the basic chrome sulphate by the addi-
tion of an alkali or an alkaline carbonate to the solution of
the neutral salt. It was Prof. Knapp who first published
this process as early as 1858 ; but it was not until 1893 that
it was shown to be of practical value, and was then patented
in this country by Martin Dennis. Since that time it has
been in general use with but slight modifications, i
The chrome tan is used only to a limited extent in the
tanning of furs, the method requiring very careful treat-
ment and accurate supervision during the various stages of
the process, and the leather coming out colored a pale-blue-
green tint, which for some purposes is objectionable. In
some plants ponies and rabbits are tanned with chrome;
and when the skins are to be dyed by means of certain coal
tar dyes, they have to receive a chrome tannage. The
leather produced by a chrome tan is very durable, and pos-
sesses great resistance to the action of water.
57
FUR DRESSING AND FUR DYEING
Any salt of chromium, with either mineral or organic
acids, can be used, but chrome alum is the one most com-
monly employed. If a skin is entered directly into a solu-
tion of a chrome salt made basic with an alkali, the precipi-
tation of the insoluble basic salt will take place very rapidly,
and the tanning will be only superficial. The procedure
is therefore first to treat the skins with a chrome solu-
tion which forms only small quantities of the basic salt.
After the skins are impregnated with the solution, this is
made basic, so that the real tan will take place within the
skin tissues among the fibres of the corium. A common
formula is the following: 5 Ibs. of chrome alum are dis-
solved in 10 gallons of water. The skins are entered into
the solution at about 70 F. and paddled for about 2 hours,
or drummed for one hour. Then a solution of three pounds
of washing soda is added slowly to the liquor which is then
stirred up well, and the skins drummed or paddled again
for an hour or two, and then left in the liquor for 12 to 24
hours till completely tanned. The skins are rinsed, and
washed in a \% solution containing f % of the weight of
the skins of borax. The pelts are then well washed in clean
water, hydro-extracted and dried.
C. Iron Tan
Tanning by means of iron salts has thus far been merely
a matter of scientific interest and has not found any practi-
cal use. The principle involved is identical with that of
the preceding mineral processes.
3. CHAMOIS TAN
The chamois dressing, as previously noted, is undoubt-
edly the oldest method of preparing leather from skin, the
various fat-containing substances derived from animals,
fish, birds, etc., being used for the purpose. The chief ob-
ject of the fat was to coat the fibres of the skin, thus pre-
58
TANNING METHODS
venting their adhesion, and at the same time rendering
them resistant to water. In the true chamois tan, the
fat seems to have also a chemical function in contradistinc-
tion to the other which is merely physical or mechanical.
For, if skins tanned by the chamois process be treated with
a weak solution of an alkali, all the fatty materials should
be removed thereby, but this happens only to a small ex-
tent, the pelt retaining its softness and pliability, and the
other characteristic qualities of leather, indicating that the
fat is combined intimately with the skin substance in a
permanent fashion.
In tanning furs, various oils and fats are used, but not
all are capable of producing a chamois tan. Among the
fatty materials are mineral oils, and vegetable and animal
oils and fats. Mineral oils are the distillation products
of petroleum, partially liquid, and partially solid. Being
inert substances, they have no tanning effect, but serve
merely as water-proofing or fattening materials. Except
for their oily nature they have nothing in common with
fats, being quite unaffected by solutions of alkalies or of
acids.
Vegetable and animal fats and oils are, when pure,
neutral substances formed by the combination of fatty acids
with glycerine. They possess the property of saponifica-
tion, that is, of forming a soap when treated with an alkali,
the soap being the alkaline salt of the fatty acid. Under
certain conditions, the fat can be split up into free fatty
acid and glycerine by the action of acids, or even water
alone. Some fats on long standing, split up in this way
spontaneously in the presence of moist air. As a general
rule, those fats which exhibit this property to a marked de-
gree are affected by contact with the air, due to the ab-
sorption of oxygen which reacts chemically with the fats,
forming what are known as oxy-fatty acids, usually less
soluble, and having a higher melting point than the original
fats. Vegetable and animal fatty materials are classified
59
FUR DRESSING AND FUR DYEING
on the basis of this phenomenon of absorbing oxygen from
the air, those possessing this quality to a great degree be-
ing called " drying oils/' others being " partially drying,"
or " non-drying." Olive oil, castor oil, cocoanut oil and
cottonseed oil are examples of non-drying or partially-dry--
FIG. 8. TRAMPING MACHINE OR " KICKER/'
(F. Blattner, Brooklyn, New York.)
ing vegetable oils, linseed oil being the most important
drying-oil in this class. Tallow, lard, butter-fat, neats-foot
oil are non-drying animal fats, the drying oils being seal
oil, whale oil, and cod-liver oil.
For tanning purposes, this property of absorbing oxygen
is important, because only with drying oils can a true
chamois tan be obtained, non-drying oils acting like mineral
60
TANNING METHODS
oils only as water-proofing materials. The details of the
chamois process are not quite clear, there being considerable
difference of opinion on the matter. But all the studies on
the subject tend to prove that there are at least two phases
to the process: first, the mechanical covering of the fibres
with the fat, this property being common to all fats or oils
which may be used; and second, the combination of the
fat with the skin in some chemical way, as a result of the
oxidation of the fat, a characteristic found only in the dry-
ing oils. During the oxidation of the fats, the glycerine in
them is converted to acrolein or acryl-aldehyde, which also
aids the tanning. It was at one time supposed that the tan-
ning action was due to this aldehyde alone, but a chamois
tan can be made with fatty substances from which all the
glycerine has been removed. The evidence on this question,
however, is not quite conclusive.
In general, the procedure of the chamois tan is as follows:
The hydro-extracted, fleshed skins are rubbed on the flesh-
side with a good quality of seal-oil. They are then folded
up, and put into a ' kicker,' where they are tramped for
two or three hours to work in the oil. The kicker is a
machine such as shown in Fig. 8 consisting of a receptacle
for the skins, and two wooden hammers which work up
and down mechanically, turning and pounding the skins.
(As many as 1000-1500 skins of the size of musk-rats can
be worked at one time in such a machine.) The pelts are
then taken out and hung up in a warm room for several
hours, considerable oxidation taking place. Another coat
of oil is then applied, which is again tramped in, and the
skins are hung up once more and exposed to the air to
cause the oil to oxidize. After the skins are sufficiently
tanned they are rinsed in a weak soda solution to remove
the excess oil, washed and dried. When skins with fine hair
such as marten, sable, mink, etc., receive a chamois tan,
they are not tramped in kickers as the delicate top-hair
will be broken, and the value of the skin thereby reduced.
61
FUR DRESSING AND FUR DYEING
Instead they are placed in small drums, together with metal
balls of varying sizes and weights depending on the parti-
ular fur treated, and the oil is worked in by rotating the
drum. Such a ball-drum, as it is called, is shown in Fig. 9.
FIG. 9. BALL DRUM.
(F. Blattner, Brooklyn, New York.)
In conjunction with the chamois tan may be discussed
the process of oiling, inasmuch as the method of application
and the effect are both similar to the chamois tan up to a
certain point. It is customary to treat skins tanned by any
other method but the chamois process, with some oil in
order to render them more impervious to water. The great-
est variety of oils and fats can be used, the action in most
cases being simply the mechanical isolation of the skin
fibres by such a substance, thus corresponding to the first
62
TANNING METHODS
or physical phase of the chamois tan. The chemical phase,
if it takes place at all, is usually slight, and is merely in-
cidental. Oiling is generally applied either before drying
after tanning, or after drying, the oiled skins being placed
in a kicker and tramped to cause the oil to penetrate. In
some instances the oiling material is put in the same mix-
ture as the tanning chemicals, and the tanning and oiling
are effected simultaneously.
Among fatty substances used for oiling are mineral oils,
such as paraffine oil, and vaseline; animal fats, like train
oils, butter, egg-yolk, glycerine, neats-foot oil; vegetable
oils, like olive oil, castor oil, cottonseed oil; also sul-
phonated castor oil and sulphonated neats-foot oil. These
may be used singly or in various mixtures, an emulsion of
an oil and a soft soap also being frequently employed.
4. FORMALDEHYDE TANS
Formaldehyde has proven to be of great value in the tan-
ning of furs, usually in conjunction with other processes.
Formaldehyde is a gas with a strong, irritating odor, and its
40% solution, which is the customary commercial form, also
possesses this quality. When skins are treated for several
hours with a very dilute solution of the commercial product,
a leather is obtained which combines the properties of the
alum tan and the chamois tan. Moreover, in the majority
of observed cases, where furs have been tanned with for-
maldehyde, the skins seem to acquire a certain immunity
to the attacks of vermin and moths. Although the skins do
not in any way retain the odor of the formaldehyde, never-
theless these destructive agents seem to be repelled.
Numerous processes have been devised which use for-
maldehyde in connection with other substances for tan-
ning. Thus in a German patent is described a method in-
volving the alternate or simultaneous treatment of pelts
with solutions of formaldehyde and alpha or beta naphthol.
63
FUR DRESSING AND FUR DYEING
Both the formaldehyde and the naphthol exercise tanning
actions, but the process is not used in practise.
In 1911, Stiasny, a well-known leather chemist produced
a synthetic substance by the condensation of formaldehyde
with a sulphonated phenol, forming an artificial tannin.
This chemical, called " Neradol D," exhibits many of the
properties characteristic of true tannins, although in no
way related by structure and composition. By the use of
" Neradol D " a soft, white and flexible leather is obtained,
and it is therefore a suitable tanning material for furs.
5. COMBINATION TANS
In many instances more than one method is employed in
tanning the furs, and in this way what is known as a com-
bination tan is produced. While the various individual
processes described give more or less satisfactory results by
themselves, they generally possess some features, which for
certain purposes may be undesirable, and which can be elim-
inated or considerably reduced by using other processes at
the same time or subsequently. Some of the combination
methods are, pickle with chrome tan, alum tan with chrome
tan, and formaldehyde tan with pickle, mineral tan or
chamois tan. By means of such combinations various
qualities of tanned furs can be obtained, and if it is desired
to produce a pelt having certain special characteristics, this
can be brought about by combining two or more standard
methods.
Some illustrations of combined tannages are the follow-
ing: Alum-chrome tan. The skins are tanned by the regular
alum process, then the constituents of the chrome tan are
dissolved directly in the same bath, and the chrome tan is
effected as usual. Chrome-formaldehyde tan. To the regu-
lar chrome tan solution is added -|lb. of formaldehyde for
every 10 gallons of chrome liquor. The rest of the process
is as ordinarily.
64
TANNING METHODS
6. VEGETABLE TANS
In practise, the vegetable tanning matters are not used
for furs, although in some special instances gambier cutch
may be employed occasionally with some other tan. How-
ever, many of these tannins also have dyeing properties,
and are used in dyeing the furs. In this connection it must
be mentioned that furs dyed with these materials also re-
ceive a vegetable tan, which improves the quality of the
leather to a considerable extent.
Comparison of The Various Tanning Methods
fin choosing a method for tanning any particular kind of
fur, several factors must be considered. The nature of the
pelt, insofar as it is weak or strong; the time, labor and
cost of materials required by the tanning process ; the effect
on the leather of the different dyes and chemicals used in
dyeing, if the skin is to be dyed, are a few of the points re-
quiring attention and consideration^)
For furs which are only to be dressed, a simple tan like
the pickle will suffice in most cases) Special instances, such
as the rabbit and mole already mentioned, and a few other
furs are tanned by the alum method. The pickle is un-
doubtedly the cheapest and simplest method of tanning
skins, and yields a soft, white leather which is permanent
as long as it is kept dry. If it is put into water, about 25%
of the salt contained within the pelt dissolves out, and the
acid present swells up the tissues. If the skin is dried in
this condition, it will come out hard and brittle, tending to
crack very easily. By treating the leather before drying with
a strong salt solution, a good deal of the extracted salt will
be replaced, and on drying and stretching, it will work out
soft. Skins tanned by the " Schrot-beize " are affected by
water in quite the same manner as the pickled skins.
The alum tan gives a leather similar to that produced by
65
FUR DRESSING AND FUR DYEING
the pickle, but with the advantage that the skins possess
greater stretch and flexibility. In its resistance to water,
the alum-tanned pelt is quite as susceptible as the other.
As a general rule, the skin absorbs about 6% of its weight
of alum from the tanning solution, but gives up three-
quarters of this when it is soaked in water, produc-
ing on drying, a hard, stiff leather. The chrome tan is
especially impervious to water, easily resisting temperatures
of 80 C, and even boiling water. It is employed to only a
limited extent on account of the special effort and care re-
quired to obtain satisfactory results, also because the pelt
acquires a pale blue-green color which is not desired on
dressed skins. The chamois tan, and some of the combina-
tions of the formaldehyde tan with the other methods, give
very soft, flexible leathers which possess a sufficiently great
resistance to the effects of water and heat.
In tests made to determine the best working tempera-
tures for dyeing skins dressed by the salt-acid tan, and for
skins dressed by the chamois process, some very interesting
facts were brought out. These two tans were chosen be-
cause they represent opposite extremes, the salt-acid tan
usually giving the poorest results/ and the chamois tan
giving the best results in practise in dyeing; Other
methods, except the chrome, range between these two. The
procedure in these experiments was to treat the skins at
ordinary temperatures in water, or dilute solutions of the
various chemicals and dyes usually employed in dyeing,
and then heat these solutions until the leather just began
to shrink and shrivel up. This point, called the shrinking
point (S.P.), gave the temperature to which the skins could
be subjected in the given solution without danger to the
pelt. (The experiments and observations were made by
Erich Schlottauer, while director of a large German fur
dressing and dyeing plant).
The first observation made was that different furs tanned
by the same process were affected differently in the same
66
TANNING METHODS
solutions. Thus in plain water, three furs, all tanned by the
acid-salt tan, had shrinking points varying by several de-
grees; similarly with two different furs tanned by the
chamois process, there was a variation in the shrinking
point of two degrees. The explanation of this discrepancy
among the different skins may be that there was a slight
difference in the conditions under which they were tanned,
experiments showing that a maximum difference of 4C,
may exist among skins tanned by the same process, but
not under the same or identical circumstances. Another
reason for the variation may be the fact, that some skins
are more greasy than others, and are thus more resistant
to the effects of water or of some chemicals. The furs with
the higher shrinking points in water were those which
naturally are more greasy than the others.
Weak solutions of acids tend slightly to lower the shrink-
ing point, while weak solutions of alkalies appreciably
raise it, in both chamois-tanned and salt-acid-tanned skins.
Solutions of dyes and mordants as a general rule increase
the resistance of the skin to heat, varying quantities of
these substances having no, or little different effects on the
shrinking points. Previous treatment of the leather with
some oil considerably raises the shrinking point of the
pelt. Formaldehyde effects a great increase of the resist-
ance of the skins to heat, especially with chamois-tanned
furs. The experiments in this case were made by first treat-
ing the skins in the weak formaldehyde solution, and then
determining the shrinking point in plain water.
Two skins, both dressed by the " Schrot-beize," a Persian
lamb and an astrachan, after dyeing had shrinking points
almost 10 degress higher than when undyed. The extra
tannage which the skins received from the tannins used in
the dye mixtures for these furs, accounts for this increased
resistance to heat.
The following tables give the observed figures in the
different experiments:
67
FUR DRESSING AND FUR DYEING
TABLE I
A
S.P.
B
S.P.
C
S.P.
Salt-acid Tan
Australian Opossum
IVIarmot
C.
46
45
C.
58
50
C.
45
42
Skunk
47
56
43
Chamois Tan
Mink
52
61
45
Muskrat
50
58
42
A Water
B Water plus 1% Ammonia (s.g. 0.910)
C Water plus 1% Sulphuric acid (66 Beaume)
TABLE II
A
B
C
S.P.
S.P.
S.P.
Salt-acid Tan
C.
C.
C.
Australian Opossum
53
52
54
Chamois Tan
Mink
59
59
59
A 1000 c.c. water plus 40 c.c. Peroxide plus 5 c.c. ammonia
B 500 c.c. water plus 2 grams Ursol D (Para-phenylene-
diamine)
C 500 c.c. water plus 5 grams Ursol D
68
TANNING METHODS
TABLE III
A
B
C
D
S.P.
S.P.
S.P.
S.P.
Salt-acid Tan
C.
C.
C.
C.
Australian Opossum . .
51
51
53
56
Chamois
Mink
59
59
61
62
A 500 c.c. water plus 5 grams ground nut-galls
B 300 c.c. water plus 2 grams pyrogallic acid
C 500 c.c. water plus 2 grams potassium bichromate
D Water, after treating leather with rapeseed oil
TABLE IV
A
B
C
D
S.P.
S.P.
S.P.
S.P.
Salt-acid Tan
C.
C.
C.
C.
Australian Opossum . .
49
49
55
50
Chamois Tan
Mink
59
67
69
70
A 500 c.c. water plus 5 c.c. formaldehyde for 1 hour
B 500 c.c. water plus 5 c.c. formaldehyde for 12 hours
C 500 c.c. water plus 10 c.c. formaldehyde for 3 hours
D As in C, but treated with 500 c.c. water plus 5 c.c.
ammonia, instead of water alone.
TABLE V
A
S.P
B
S.P.
Persian Lamb
C
44
C
54
Astra chan
47
55
A Before dyeing
B After dyeing
69
FUR DRESSING AND FUR DYEING
As a result of these experiments it may be concluded
that the maximum temperature for drying salt-acid tanned
skins should be 40 C., while for chamois tanned skins the
temperature may be permitted to reach 45 C. without any
danger of the leather being affected. Moreover, in the case
of pickled skins, the matter of extraction of the tanning
agent, as well as that of the leather becoming " burned "
may be effectively counteracted by brushing some oil or
fat on to the leather side before dyeing the pelt.
The shrinking points of skins dressed by the various tan-
ning methods are constant within certain limits, depending
on the nature of the skin and on the conditions of tanning,
and it is possible by observing the shrinking point, in con-
junction with other characteristics of a given pelt, to de-
termine what method of tanning was used.
70
CHAPTER VI
FUR DRESSING
DRYING AND FINISHING
x^v/XE of the most important operations of all the
I 1 fur dressing processes is the drying of the skins..
V^X por even when all the previous steps have been
successfully completed, there is still a great possibility of
the skin being injured if the drying is not properly and
carefully carried out.
/The essential requirements for good drying are proper
temperature, uniformity and rapidity/ The leather part
of the fur cannot, in the moist state, resist temperatures ex-
ceeding about 45 centigrade, for when dried, the skin turns
out hard and stiff, and cracks easily. The furs must there-
fore be dried at an initial temperature of 25 to 30 centi-
grade, and as the moisture is gradually removed, the tem-
perature may be raised, for the less water that remains in
the pelt, the less is the leather affected by the heat, and the
more difficult is the removal of its aqueous content.
If the drying process is not a uniform one, that is, if
all the skins in a lot are not subjected to the same drying
conditions, then after the drying has proceeded for a cer-
tain time, some skins may be quite dry while others are
not, or there may be as many different degrees of dryness
as there are skins drying. There is also the possibility of
great variation in the amount of moisture removed from
different parts of the same skin. Such a state of affairs re-
quires an extra expenditure of time, labor and heat power
in order to get the whole lot of furs into a more or less uni-
form condition. Moreover in some kinds of furs, especially
71
FUR DRESSING AND FUR DYEING
those with thick skins, when the drying is not even, there is
danger of the epidermal layer drying away from the corium,
and subsequently peeling and cracking. Uniformity of dry-
ing requires the maintenance of a reasonably constant tem-
perature equally distributed throughout all parts of the
space where the drying is done, so that all the furs may be
dried under the same conditions.
Rapidity of drying is desirable not only because it is
beneficial to the condition of the pelt, but also from the
point of view of practical business economy. The space
occupied by the drying should be as small as possible com-
patible with the volume of work, and with the efficiency
of operation. Slow drying involves the use of much space
to take care of all the skins to be dried, or an accumula-
tion of pelts ready to be dried, neither of which conditions
is efficient or desirable.
It was formerly the general custom, still practised in
some establishments, to dry the skins by hanging them up,
leather-side out on lines in a large room or loft, the heat
being usually supplied by steam pipes. Such a procedure
occupied often as long as two or three days to get complete
drying, involved a great deal of labor, and the results were
far from uniform. In fact, in order to get the skins more
nearly equable, it was necessary to subject them to an
additional operation. This usually consisted of rotating the
skins in a closed drum for several hours, the constant inter-
mingling of the pelts in contact with each other causing any
moisture left in them to be evenly distributed throughout
the whole lot. The skins, by this process also are rendered
somewhat softer and more flexible, but by drying under
proper conditions the entire extra operation can be dis-
pensed with, the furs coming out quite as soft and flexible
without the drumming.
A great improvement was the adoption of large fans to
circulate the heated air in the loft, thereby approaching
more nearly an even temperature. More modern devices
72
DRYING AND FINISHING
have, however, been developed, whereby drying can be
effected in the most uniform manner, with perfect control
of temperature, and requiring the least possible consump-
tion of space, time, labor and power. A typical arrange-
ment consists of a large closed chamber, generally con-
structed of steel, and divided into several compartments
each of which may be operated independently of the others.
Air, heated over suitably located steam pipes to the re-
quired temperature, is forced through the various com-
partments by means of fans operated by power. The con-
ditions may be varied in each compartment, as to tempera-
ture or humidity, both of which can easily be regulated, or
all the compartments may be used together as one unit.
The skins are hung up on rods or lines in the compart-
ments, or on special frames for the purpose, which are then
entered into the compartments and the doors shut. The
dry, heated air is forced to pass over the skins, and takes
up their moisture. At the further end of the drying cham-
ber is another fan which removes the moisture-laden air
after it has done its work. The drying is effected in from
6 to 24 hours, and all skins are obtained in the same condi-
tion, for the process is quite uniform and regular.
Within recent years there has been evolved a highly
efficient and economical drying equipment, based on a
samewhat different principle than underlies any of the
foregoing methods. The conveyor type of dryer, as it is
called, is admirably suited to the needs of the fur dressing
and dyeing industry, and is undoubtedly superior to any
of the previous systems of drying furs, in that it affords
an enormous saving of space, time, labor and power, and
gives greater uniformity and presents better working con-
ditions.
The conveyor dryer consists essentially of a steel enclo-
sure, through which the skins pass on horizontal conveyors.
Where special insulation is necessary, asbestos panels are
used to line the enclosure, making the dryer absolutely
73
FUR DRESSING AND FUR DYEING
fireproof, and enabling the maximum utilization of heat.
In the middle of the dryer are located the steam coils which
furnish the heat, and in many instances exhaust steam can
iM-K/ -vj __
-s
y w
S
a I
*^ ^D
< c
Q
o
g
pq
be used as the source of heat. Figure 10 shows diagram-
matically the arrangement and operation of the conveyor
type of dryer. The enclosure is divided into several com-
74
DRYING AND FINISHING
partments, in each of which a different condition of tem-
perature and humidity is maintained, the temperature be-
ing closely and accurately regulated by an automatic
control, and once the dryer has been set for any condition,
all skins will be dried exactly the same, regardless of
weather or season.
75
FUR DRESSING AND FUR DYEING
The skins to be dried are placed on poles which in turn are
set on the horizontal conveyors as in Fig. 11.) As the skins
pass through the compartments, large volumes of air, heated
to the required temperature over the steam coils, are cir-
culated among the skins by means of the fans. Exhaust
fans, properly placed, remove a certain quantity of mois-
ture-laden air when it has accomplished its full measure of
work. When the skins on the conveyors have passed the
full length of the dryer, they are entirely dry, and are then
removed from the poles. (Fig. 12). The time required
for drying varies according to the nature of the fur from
1-2 hours to 6-8 hours. In tests made to determine the
relative efficiency of the conveyor type of dryer as against
the old " loft " method, it was found that there was a saving
of over 50% in power, and of 85% in floor space, as well
as a great saving of labor, when the conveyor system was
used, the number of skins dried in a given period of time be-
ing the same in both cases. The advantages of the new
method are easily apparent, and the saving is sufficiently
great with large lots of furs, to make an appreciable differ-
ence in the final cost of dressing.
If the skins have been dried by a modern drying system
they all come out in a uniform condition, and are ready to
go on immediately to the next operation. If, however, a
form of the " loft " method of drying has been used, it is
customary to subject the skins to an additional process.
The dried pelts are put in drums with damp sawdust, and
drummed for a short time in order to get them into the
proper condition. The drumming is essential for the pur-
pose of equalizing the condition of the pelts, some being
drier than others, and as a consequence of the contact with
the moist sawdust, they are all brought to the same degree
of dryness. As a result of this operation also, the skins be-
come considerably softened.
Then if the pelts have not been previously oiled during
the tanning process, or prior to the drying, they receive this
76
DRYING AND FINISHING
treatment now. The oil or fat is applied to the leather side
of the furs, which are then placed in the tramping machine
= 1
I!
1 t
for a short time in order to cause the oil to be forced into the
skin. The fibres of the corium thus become coated with a
thin layer of fatty material, which contributes greatly to
77
FUR DRESSING AND FUR DYEING
the softness and flexibility of the pelt, and increases its
resistance to the action of water, and also, in certain in-
stances a partial chamois tan is produced, thereby improv-
ing the quality of the leather.
The skins are now returned to the work bench, and sub-
jected to the stretching or " staking " process. This con-
sists in drawing the skin in all direc-
tions over the edge of a dull blade,
which is usually fixed upright in a
post with the edge up. Or, the
stretching may be done on the
fleshing bench, substituting a dull
blade for the fleshing knife. Re-
cently staking machines are being
used in the larger establishments,
the work being done much more
quickly and efficiently. As a result
of this operation, the leather be-
comes very soft and flexible, every
bit of hardness and stiffness being
eliminated, and the skins receive
their maximum stretch, thereby giv-
ing the greatest possible surface to
the pelage. This not only helps to
bring out the beauty of the hair, but
is also a decided advantage from the
FIG. 13. STRETCHING economic point of view, as a con-
MACHIXE FOR CASED SKINS i -\ -i r i rr
siderable saving of material is effect-
( Reliable Machine Works, j ,1 . ,.
Evergreen, L. I.) ec * m this wa y? sometimes even to
the extent of twenty-five per cent.
Cased skins are stretched in a somewhat different manner,
by means of stretching irons. These consist of two long-
iron rods joined by a pivot at one end. The skins are
slipped on to the irons, which are then spread apart, and
in this way the skins are stretched and softened. A machine
which does this work very efficiently is shown in Fig. 13.
78
DRYING AND FINISHING
The skin is drawn onto the stretching arms, in this case
made of bronze, which are then forced apart by pressing on
a pedal. When properly stretched to the maximum width
in all directions possible, and thus thoroughly softened, the
FIG. 14. FUR BEATING MACHINE.
(S. M. Jacoby Co., New York.)
skin can easily be reversed, that is, turned hair-side out. As
many as 6000 skins can be stretched, or 4000 to 5000 skins
stretched and reversed by one man in one day on such a
machine.
\The pelts are then combed and beaten. ) In smaller
plants these operations are done by hand, but suitable
79
FUR DRESSING AND FUR DYEING
machines are being employed. In order to straighten out
the hair, it is combed or brushed. Then in order to
loosen up the hair, and to cause it to display its fullness, the
furs are beaten. This process is also done by hand in some
establishments, but up-to-date places use mechanical de-
vices for this purpose. A type of machine which has proven
very successful, and is enjoying considerable popularity is
shown in Fig. 14. These machines are also made with
special suction attachments which remove all dust as it
comes out of the beaten skin, thereby making this formerly
unhealthful operation thoroughly sanitary and hygienic.
vThe final process is drum-cleaning. This operation is
intended specifically for the benefit of the hair part of the
fur, and is very important inasmuch as the attractive ap-
pearance of the fur depends largely upon it/) The drum,
such as is shown in Fig. 15 is generally macfe of wood, or
sometimes of wood covered with galvanized iron. The skins
together with fine hardwood sawdust are tumbled for 2 to 4
hours, or sometimes longer. Occasionally a little asbestos or
soapstone is added to the sawdust; for white, or very light-
colored skins, gypsum or white sand is used, either alone, or
in admixture with the sawdust; and for darker skins,
graphite or fine charcoal is sometimes added in small quan-
tities. (The drum-cleaning process polishes the hair, giving
it its full gloss and lustre, and at the same time absorbing
any oil or other undesirable matter which may be adhering
to the hair as a result of the washing and tanning processesj
Any soap, or traces of mordant are wiped off and so re-
moved, and by using heated sawdust, or heating the drum
while rotating, the fur acquires a fullness and play of the
hair which are great desiderata in furs. The sawdust must
then be shaken out of the furs. This is done by cageing.
In some instances, the drum itself can be converted into a
cage, by replacing the solid door with one made of a wire
screen. (Fig. 16.) Usually, however, the skins are removed
from the drum and put in a separate cage, which is built
80
DRYING AND FINISHING
like the drum, but has a wire net all around it, through
which the sawdust falls, while the skins are held back.
The cages are generally enclosed in compartments in order
to prevent the sawdust from flying about and forming a
dust which would be injurious to the health of the workers.
FIG. 15. DRUM. (COMBINATION DRUM AND CAGE AS A DRUM)
(F. Blattner, Brooklyn, New York.)
In large establishments, the drum-cleaning machinery occu-
pies a large section of the plant, many drums and cages
being used, and special arrangements being made to take
care of the sawdust which can be used over again several
times, until it becomes quite dirty.
With this operation ends the ordinary procedure of fur
dressing. But there are several additional processes re-
quired in the treatment of certain furs, which are generally
81
FUR DRESSING AND FUR DYEING
undertaken by the dresser, and chief among these are shear-
ing and unhairing. Sometimes this work is done in separate
establishments organized solely for this business. Certain
FIG. 16. CAGE. (COMBINATION DRUM AND CAGE AS A CAGE.)
(F. Blattner, Brooklyn, Xcw York.)
kinds of furs, among them being seal, beaver and nutria,
possess top-hair which may detract from the beauty of
the fur, the true attractiveness being in the fur-hair. The
top-hairs are therefore removed, and for this purpose
machines are now being used. Formerly this work was all
done by hand, and on the more expensive furs like seal
and beaver, unhairing is now done on a machine operated
by hand. The principle of the process is as follows: The
skins are placed on a platform and the hair blown apart by
82
DRYING AND FINISHING
means of a bellows. The stiff top-hairs remain standing up,
and sharp knives are brought down mechanically to the de-
sired depth, and the hair is cut off at that point. The skin
FIG. 17. UN HAIRING MACHINE.
(Seneca Machine & Tool Co., Inc., Brooklyn, N. Y.)
is then moved forward a short distance, and the process re-
peated until all the top-hairs have thus been cut out. With
muskrats, or other pelts which do not require such very
careful attention, the whole process is done automatically
on a machine. The fur-hair is brushed apart by means of
brushes and a comb, and at regular intervals, sharp knives
cut off the top-hairs. Several hundred skins can be un-
haired in a day on such a machine requiring the atten-
tion of only one man. A machine for unhairing skins is
shown in Fig. 17.
With other furs, such as rabbits, hares, etc., where the
trouble of unhairing would be too great commensurate with
83
FUR DRESSING AND FUR DYEING
its advantages, the hair is sheared instead. The top hair is
cut down to the same length as the under-hair by means of
FIG. 18. FUR-SHEARING MACHINE.
(Seneca Machine & Tool Co., Inc., Brooklyn, N. Y .}
shearing machines which can be regulated to cut to any de-
sired length of hair. A typical device for shearing furs is
shown in Fig. 18.
84
CHAPTER VII
WATER IN FUR DRESSING AND DYEING
THE assertion has often been made, although its
absurdity is now quite generally realized, that the
success of the European fur dressers and dyers,
particularly in Leipzig, is due to the peculiar nature of the
water used, which is supposed to be especially suited for
their needs. The achievements in this country in the fur
dressing and dyeing industry during the past few years
are ample and sufficient answers to the claim of foreign
superiority in this field no matter what reason maybe given,
and particularly when the quality of the water used is ad-
vanced as a leading argument. For the water employed
by the establishments in and about New York, as well as
in other sections of the country is surely not the same as
the water of Leipzig, yet the work done here is in every re-
spect the equal of, if not better than the foreign products.
It is interesting to note that similar rumors were cur-
rent here in the early period of the development of the
American coal-tar industry since 1914. Our efforts to estab-
lish an independent dyestuff industry were doomed to fail-
ure, according to those who circulated the stories, because
we did not have the water, which they claimed was respon-
sible for the German success. The present status of the
American dye business, in its capacity satisfactorily to
supply most of the needs of this country and of others as
well, speaks for itself.
However, as is often the case with such erroneous asser-
tions, there is just enough of an element of truth in the
statement regarding the peculiar qualities of certain kinds
of water, to make the matter worthy of consideration.
85
FUR DRESSING AND FUR DYEING
Water is certainly a factor of great importance in fur
dressing and dyeing, and it is not every sort of water that
is suitable for use. This fact was recognized by the early
masters of the art, for they invariably used rain-water as
the medium for their tanning and dyeing materials, and
their choice must be regarded as an exceedingly wise one.
While the necessity for giving consideration to the quality
of the water for fur dressing purposes is great, it is in fur
dyeing that the effects of using the wrong water are largely
evident, and so extra care must be exercised in the selection
of water for this purpose.
The essential requirements for a water suitable for the
needs of the fur dressing and dyeing industry, are: first, a
sufficient, constant and uniform supply ; and second, the ab-
sence of certain deleterious ingredients. Chemically pure
water is simply the product of the combination of two parts
by volume of hydrogen with one part by volume of oxygen.
Such water can only be made in the laboratory, and is of
no importance in industry. For practical purposes, dis-
tilled water may be regarded as the standard of pure water.
Here, too, the cost and trouble involved in the production
of distilled water on a large scale is warranted only in
a certain few industrial operations. A natural source of
water which in its character most nearly approaches dis-
tilled water is rain. In fact, rain-water is a distilled water,
for the sun's heat vaporizes the water from the surface of
the earth forming clouds, which on cooling, are condensed
and come down as rain. Rain-water is usually regarded
as the purest form of natural water. Exclusive of the first
rain after a dry period, rain-water is quite free of impuri-
ties, except possibly for a small percentage of dissolved at-
mospheric gases, which are practically harmless, and which
can usually be readily eliminated by heating the water.
Moreover, rain-water is quite uniform in its composition
throughout the year in the same locality, and it possesses all
the desirable qualities of a water suited for fur dressing and
86
WATER IN DRESSING AND DYEING
dyeing purposes. Formerly when the quantity of water
used in the industry was comparatively small, the supply
from rain was sufficient to meet all the requirements. But
now, when tremendous quantities of water are used con-
stantly, rain-water is no longer a feasible source, and other
supplies must be utilized, although in a sense, all water
may be traced to rain-water as its origin.
When rain-water falls on the earth it either sinks into
the ground until it reaches an impervious layer, where it
collects as a subterranean pool, forming a well, or continues
to flow underground until it finally emerges at the surface
as a spring; or on the other hand the rain-water may sink
but a short distance below the surface, draining off as
ponds, lakes or rivers. In the first case the water is called
ground water, in the latter it is known as surface water.
Ground water usually contains metallic salts in solution,
and relatively little suspended matter. If the water has
percolated through igneous rocks, like granite, it may be
quite free even of dissolved salts, and such water is
considered " soft." If, however, the rocky formations over
which, or through which, the water has passed contain lime-
stone or sandstone, or the like, salts of calcium and mag-
nesium will be dissolved by the water. The presence of the
lime and magnesia salts, as well as salts of aluminum and
iron, in the water, causes it to be what is termed " hard."
Surface water is more likely to contain suspended matter,
with very little of dissolved substances. Suspended matter,
like mud, contains much objectionable matter such as
putrefactive organisms and iron, but most of these materi-
als can be removed by filtration or sedimentation, and sel-
dom cause any difficulties.
Hardness in water is generally the chief source of trouble
when the water is at fault. Hardness may be of two kinds,
either permanent, or temporary, or sometimes both are
found together. Water which is permanently hard usually
contains the lime and magnesia combined as sulphates.
87
FUR DRESSING AND FUR DYEING
Temporary hardness, on the other hand, is due to the pres-
ence of lime and magnesia in the form of bicarbonates, the
carbon dioxide contained in the water having dissolved the
practically insoluble carbonates :
CaC0 3 + C0 2 + H 2 Ca(HC0 3 ) 2
calcium carbon water calcium
carbonate dioxide bicarbonate
Temporary hardness can be eliminated by heating the
water, the carbon dioxide being expelled and the carbonates
of lime and magnesia being precipitated and then filtered
off. Both permanently and temporarily hard waters can
be softened by the addition of the proper chemical, such as
an alkaline carbonate like sodium carbonate. This precipi-
tates insoluble carbonates of the lime, magnesia, iron and
aluminum, leaving a harmless salt of sodium in solution in
the water. The sludge is allowed to settle in tanks before
the water is used.
In fur dressing and dyeing, water is employed for soaking
and washing the skins, dissolving chemicals, extracts and
dye materials, and also for steam boilers. A small amount
of hardness in the water is not harmful, and up to 10 parts
of solid matter per 100,000, may be disregarded. Perma-
nent hardness is particularly objectionable in water for
boiler purposes, as it forms scale. The effect of the impuri-
ties of the water depends on the nature of the chemicals and
dyes used. Where acids are used in solution compounds of
magnesium, lime and aluminum will generally not interfere.
Hard water must not be used for soap solutions, as sticky
insoluble precipitates are formed with the soap by the
metals, this compound adhering to the hair, and being diffi-
cult to remove, will cause considerable trouble in subsequent
dyeing. An appreciable loss of soap also results, as one part
of lime, calculated as carbonate will render useless twelve
parts of soap. In tanning or mordanting, where salts of tin,
aluminum or iron are employed, hard water should not be
88
WATER IN DRESSING AND DYEING
used, as lime and magnesia will form precipitates with
them. Bichromates will be reduced to neutral salts, and
cream of tartar will also be neutralized. With dyes also,
hard water has a deleterious effect. Basic dyes are precipi-
tated by this kind of water, rendering part of the dye use-
less, and also causing uneven and streaky dyeings. Some-
times the shades of the dyeings are modified or unfavorably
affected. Considerable quantities of lime and magnesia in
the water will cause duller shades with logwood and fustic
dyeings. The presence of iron, even in very slight quanti-
ties generally alters the shade, darkening and dulling
the color.
These facts were apparently all recognized and under-
stood by the fur dressers and dyers of an earlier period, for
instead of utilizing the water of lakes and streams near at
hand, which afforded a more constant supply, but which
contained harmful impurities, they collected the rain-water,
which was always soft. Whether they realized the nature
and character of the substances that make water hard is
uncertain, but they were always careful to avoid such water.
At the present time establishments located in and about
large cities like New York, where the majority of American
fur dressing and dyeing plants are situated, have no trouble
about the water. The cities supply water which is soft,
suitable alike for drinking and industrial purposes. Other
plants, not so fortunately situated, often have to employ
chemical means to treat the water so as to make it suitable
for use.
89
CHAPTER VIII
FUR DYEING
INTRODUCTORY AND HISTORICAL
IN discussing fur dyeing, the question naturally arises,
" Why dye furs at all? Are not furs most attractive
in their natural colors, and therefore more desirable
than those which acquire their color through the artifices
of man?" The answer cannot be given simply. Natural furs
of the more valuable Jdnds are indeed above comparison
with the majority of dyed furs. Yet there are several rea-
sons which fully justify and explain the need for fur dyeing,
for at the present time, this branch of the fur industry is
almost as 'important and indispensable as the dressing of
furs.
The first application of dyeing to furs, had for its pur-
pose the improvement of skins which were poor or faulty
in color; or rather, the object was to hide such defectsj As
nearly as can be ascertained, this practise was instituted
at some time during or before the fourteenth century, for
fur dyeing seems to have been common during that period,
as is apparent from the verses of a well-known German
satirist, Sebastian Brant, who lived in the latter part of
the fourteenth century:
" Man kann jetzt alles Pelzwerk farben,
Und tut es auf das schlechste gerben."
However, at a later period, there was a general condemna-
tion of the dyeing of furs, and among the list of members
of the furrier's guilds, none can be found who are described
90
FUR DYEING INTRODUCTORY
as dyers. There is a record of a decree issued by a prince
in a German city in the sixteenth century, prohibiting the
practise of fur dyeing. Inasmuch as furs were worn only
by the nobility and certain other privileged classes, and
also were very costly, there was great profit to be had by
dyeing inferior skins so as to disguise the poor color, and
then selling such furs at the price of superior quality skins.
This was undoubtedly the reason for the prohibitory de-
cree, but there were some who continued to practise the
forbidden art in secret, using secluded and out-of-the-way
places for their workshops, and mixing their carefully-
guarded recipes with as much mystery as the witches did
their magic potions. These circumstances probably ac-
count for the great amount of mystery which has been, and
still is to a considerable degree, attached to fur dyeing,
and also explains the opprobrium and distrust with which
fur dyers were formerly regarded.
f Even at the present time, dyeing is often employed toj
I improve furs which are faulty in color. It frequently hap-
pens, that in a lot of skins there are some which are con-,
siderably off shade, or in which the color is such as to ap-
preciably reduce their value below the average, the hair
being usually too light a shade, or of uneven coloring. By ;
carefully dyeing these skins of inferior color, they can be
made to match very closely the best colored skins of the par-
ticular lot of furs, and consequently increase their value. /
With most of the cheaper kinds of furs, the trouble and cost
of improvement by dyeing would not be worth while today ;
but with some of the more valuable furs, and especially
such as are very highly prized, like the Russian sable, or
marten, or chinchilla, the darkening of light skins by the
skillful application of fast dyes to the extreme tips of the
hair, will increase their value sufficiently to warrant the ex-
pense. This dyeing or " blending " as it is called in such
cases, is done in such a clever and artistic manner that only
experts can distinguish them from the natural. Dyeing
91
FUR DRESSING AND FUR DYEING
used for such purposes is not objectionable, provided
the skins are sold as dyed or " blended."
There are certain kinds of furs, such as the various lambs,
Persian, Astrachan, Caracul, etc., which are never used in
their natural color, because it is usually of a rusty brownish-
black. These are furs possessing valuable qualities other-
wise, so they are dyed a pretty shade of black, which brings
out the beauty of the fur to the fullest extent. Sealskins
are also dyed always. Formerly they were dyed a deep,
rich dark brown, resembling the finest shades of the natural
color, but now the seals are dyed black with a brownish
undertone, a color quite different from the natural. While
these two instances cannot be said to be cases of dyeing to
disguise faulty color, they are examples of improvement of
color by dyeing.
Closely associated with the use of dyes to increase the
value of a fur by improving its color, is the dyeing of skins
of a certain lot of furs to produce a uniform shade, thereby
facilitating or to a considerable degree eliminating the task
of matching the skins by the furrier. This is usually done
only on skins which are quite small, of which a great many
are needed in the manufacture of fur garments, because
the matching of several hundred skins would entail too
much time and labor commensurate with the value of the
fur. The most notable instance of the use of dyes to pro-
duce a uniform shade on furs is the case of the moleskin.
Occasionally, furs are dyed after being made into garments,
by careful application of dyes, in order to obtain certain
harmonious effects, such as uniformity of stripe, or to pro-
duce a desired gradation of shade among the different skins
comprising the garment.
Not infrequently, the great variety of shades and color
schemes which Nature provides in the different furs, be-
comes insufficient to satisfy the desire of the fur-wearing
public for something new. The whims of fashion always
require some novel effect, even though it be for only one
92
FUR DYEING INTRODUCTORY
season. To meet this demand for novelty, fantasy or mode
shades are produced on suitable furs, colors which do not
imitate those of any animal at all, but which, neverthe-
less, strike the popular fancy. It often happens that such
a color becomes quite popular, and enjoys a considerable
vogue, to the great profit of those who introduced the par-
ticular color effect. The best ones, however, meet with
only a comparatively short-lived demand, being soon super-
seded by different color novelties.
The basis, though, of the greatest proportion of fur dye-
ing at the present time, is the imitation of the more valu-_ t
able furs on cheaper or inferior skins. With the gradual
popularization of furs as wearing apparel since the begin-
ning of the last century, the demand for furs of all kinds
has increased enormously. The supply of furs, on the other
hand, and especially of the rarer kinds, has had difficulty
in keeping pace with the requirements, and as a result there
is a shortage. A very effective means of relieving this short-
age, to a great degree, at any rate, is the dyeing of imita-
tations of the scarcer furs on cheaper skins. There are
many animals among the more common, and more easily
obtainable ones, whose skins are admirably suited as the
basis of imitations of the more costly furs. Some of the
furs which are adapted for purposes of dyeing imitations
are marmot, red fox, rabbit, hare, muskrat, squirrel, opos-
sum, raccoon, and many others, and the imitations made
are those of mink, sable, marten, skunk, seal, chinchilla,
etc., and indeed, there are very few valuable furs, which
have not been dyed in imitation on cheaper pelts. On ac-
count of the general mystery which formerly surrounded
fur dyeing establishments, and which has persisted to this
day, although to a lesser degree, many peculiar notions
were held, even by those in the fur trade, concerning the
production of imitations. The idea that in order to
" make " a certain fur out of a cheaper skin, it was neces-
sary to use the blood of the animal imitated, is typical of
93
FUR DRESSING AND FUR DYEING
the conceptions of fur dyeing held not so long ago. To-day,
while the knowledge generally possessed about this branch
of the fur industry is meagre and vague, the air of mystery
and secrecy has become somewhat clarified, and such ideas
as are current about fur dyeing are more rational than
formerly.
f The dyeing of imitations is quite an artistic kind of work,
and indeed fur dyeing ought to be classed among the finest
of industrial arts. Some of the reproductions achieved by
dyers on a commercial scale are truly admirable. The
possibility of imitating the finer furs on cheaper skins
naturally led to abuse, the dyed furs being passed off fre-
quently on the unsuspecting and uninformed buyer as the
genuine original. In fact, this practise became so flagrant
that in England laws were enacted to remedy the evil. At
the present time, dyed furs are all sold as such, although
there always may be some unscrupulous merchants who
seek to profit by deception.) Some of the imitations and the
names of the furs for whicn they were sold, are as follows:
Muskrat, dyed and plucked sold as seal
Nutria, plucked and dyed sold as seal
Nutria, plucked and natural sold as beaver
Rabbit, sheared and dyed sold as seal or electric seal
Otter, plucked and dyed sold as seal
Marmot, dyed sold as mink or sable
Fitch, dyed sold as sable
Rabbit, dyed sold as sable
Rabbit, dyed and sheared sold as beaver
Muskrat, dyed sold as mink or sable
Hare, dyed sold as sable, fox, or lynx
Wallaby, dyed sold as skunk
White rabbit, natural sold as ermine
White rabbit, dyed sold as chinchilla
White hare, dyed or natural sold as foxes, etc.
Goat, dyed sold as bear, leopard, etc.
94
ir
;
FUR DYEING INTRODUCTORY
This list serves to indicate ^but a few of the great number
of possibilities which are available for the fur dyer to pro-
duce imitations of the better classes of furs,! Needless to
say, these imitations cannot, as a general rule, equal the
originals, because while the color is one of the most im-
portant features in judging the fur, the nature of the hair,
gloss, waviness, thickness, and also the durability are es-
sential considerations, and it is only in certain instances
that -skins used for imitations approach the originals iff
these respects. However, for the purposes and desires of
the majority of people who wear furs, the imitations are
deemed quite satisfactory, and they also have the ad-
vantage of being cheaper than the natural originals.
For whichever reason furs are dyed, there is no doubt
that the art of fur dyeing is one of the most difficult kinds
of application of dye materials. In the dyeing of the vari-
ous textiles, either as skein or woven fabric, the material is
of a uniform nature, and therefore the dye is absorbed
evenly by the fibres. Moreover, textiles are dyed at, or near
the boil, the dyestuff being more uniformly and perma-
nently taken up from solution by the fibre at elevated
temperatures.
How different is the case with furs! Far from being
homogeneous, furs present the greatest possible diversity
of fibres to be dyed. As already noted elsewhere, fur con-
sists of two principal parts, the hair and the leather, differing
widely in their actions toward dyes. As a general rule, the
leather absorbs dyestuffs much more readily than the
pelage, and inasmuch as fur dyeing is intended mainly and
primarily to apply to the hair, there is usually an appreci-
able loss of dye material due to its being absorbed by the
leather, and thereby rendered unavailable for dyeing the
hair. This fact must be taken into account in the dyeing
of furs, and the methods must be adapted accordingly.
With reference to the hair itself, not only has each "class
of furs hair of a different kind, but even in the same group
95
FUR DRESSING AND FUR DYEING
there is always a considerable divergence in the properties
of the hair. The fur-hair, being more or less of a woolly
nature, takes up the dye with comparative ease, while the
top-hair is quite resistant to the action of all dye materials.
As pointed out in the discussion of the nature of fur, on
different parts of the same pelt the hair varies in its capa-
city for absorbing coloring matters. The color of the hair,
also frequently presents a great variety throughout the skin,
both in fur-hair and top-hair. Yet with all this lack of
uniformity and homogeneity, the dyed fur must be of an
even color, closely approaching the natural, gently graded
and without any harsh or unduly contrasted effects. The
natural gloss of the hair, one of the most valuable qualities
of the fur, must be preserved. This is by no means a simple
matter, for the luster is affected by dyes and chemicals with
comparative ease, and especially careful treatment is neces-
sary to prevent any diminution of the gloss.
When the leather part of the fur is exposed to solutions
of a temperature exceeding 40-50 centigrade, it soon
shrivels up or shrinks, and on drying the pelt, becomes hard
and brittle, and therefore quite useless. Methods of fur
dyeing have to take into consideration this fact, and the
temperature of the dyebath must not be greater than 35-
40 centigrade. To be sure, certain dressings make furs
capable of withstanding much higher temperatures, but
their applicability is not universal, being suited only
for a very limited special class of dyestuffs. (V. Fur
Dressing). The necessity for employing comparatively
low temperatures, coupled with the great resistance of
the hair to the absorption of dye, even at much higher
temperatures, makes fur-dyeing a very difficult opera-
tion indeed. Another obstacle which must be sur-
mounted, is the possibility of extraction by the dye
solution, of those materials, chemical or otherwise, which
are contained in the leather, and which are the basis of its
permanence, softness and flexibility. For in the majority
96
FUR DYEING INTRODUCTORY
of dressing processes, the action of the ingredients is a pre-
servative one, and when these are wholly or partially re-
moved from the leather during the dyeing, it becomes, on
drying, hard and horny, like the original undressed pelt.
In cases where furs are to be dyed, special dye-resisting
dressings must be used, or the dyed. skins must receive an
additional dressing before drying.
Dyeings on furs, to have any value, must possess great
fastness to light, rubbing and wear, and must not change
color in time, either when the furs are stored, or when made
up into garments. The necessity for fur dyeings to have
these properties, together with the difficulties outlined
above, has greatly limited the field of available dyeing
materials, as well as the methods of application. These
will now be taken up in detail.
97
CHAPTER IX
FUR DYEING
GENERAL METHODS
EFORE the furs can be dyed, they have to undergo
certain preparatory processes: first, killing, which
renders the hair more susceptible to the absorption
of the dye ; and second, mordanting, which consists in treat-
ing the killed fur with chemicals which help the dye to
be fixed on the hair. Then the skins are ready to be dyed.
There are two principal methods by which dyes are ap-
plied to furs in practise: the brush process, whereby only
the tips or the upper part of the hair are colored; and the
dip process, whereby the entire fur, including the leather
is dyed. .'All other procedures in fur dyeing are modifica-
tions or' combinations of these two. Killing solutions
and mordanting solutions are also applied by one of
these methods, usually the dip process, although very fre-
quently combinations of the brush and dip methods are
used.
Chronologically the brush method of dyeing came first.
The early masters of the art were extremely fearful about
employing any means by which there was a possibility of
the leather being in any way affected. They naturally had
to devise such methods as would give the desired effect in
a satisfactory manner, and as would be confined solely to
the hair part of the fur, leaving the leather untouched.
By applying the dye or other material to be used, in the
form of a paste with a brush, the upper portion of the hair
only was treated. For different kinds of furs different sorts
of brushes were used, and the depth to which the hair was
98
GENERAL METHODS
colored could be controlled v by skillful manipulation of the
brushes. It was frequently necessary to give a ground color
to the hair, the lower part being dyed a different shade from
the tips. This was accomplished by spreading the dye paste
over the hair with a broad brush, and then beating the
color in with a specially adapted beating brush. With
larger furs, two skins were placed hair to hair after the dye
had been brushed on, and the color forced to the bottom of
the hair by a workman tramping on the skins. The dye-
ing of seal was a typical illustration of these procedures.
First the tips of the hair were dyed. The color was brushed
on, allowed to dry, then the excess beaten out with rods.
These operations were repeated until the proper depth of
shade was obtained, often as many as a dozen or more
applications of the dye being necessary. Then the base
color was spread over the hair, and beaten or tramped in
until the lower parts of the hair were penetrated. This
process also required drying and beating out of the excess
dye, as well as numerous applications of the dye to impart
the desired color to the hair. Prior to the dyeing, the furs
were killed, by brushing on a paste containing the essential
ingredients, drying and beating and brushing the fur, just
the same as in dyeing. It will be readily seen that such
methods were exceedingly laborious, and in some cases the
dyeing took many weeks, and even months.
It was quite a step forward when a certain fur dyer, pos-
sessing a little more courage, or perhaps, experimenting
spirit than the others, attempted to dye furs by dipping
them entirely into a bath containing a solution of the dye
instead of applying a paste as formerly. The advantages to
be gained by such a method of dyeing were many. A
large number of skins could be treated thus at one time,
and this was a very important consideration in view of the
great increase in the demand for dyed furs. By allowing
the furs to remain in the dye solution until the proper shade
was obtained, the time and labor of applying many coats of
99
FUR DRESSING AND FUR DYEING
dye by brush was considerably reduced, and in addition,
there was a greater probability of the products coming out
all alike, uniformly dyed. The results as far as the hair
was concerned, were indeed highly gratifying, but the con-
dition of the leather after dyeing was not so encouraging.
This difficulty has to a considerable degree been overcome,
although there are frequent instances of the leather being
affected by the dyeing process even with modern methods.
However, the remedy in such cases, or rather the preventa-
tive is the proper dressing of the skins prior to the dyeing.
The dip method of dyeing has acquired great importance,
and is being employed in dyeing operations involving the
/-handling of millions of skins annually. In certain in-
; stances, nevertheless, the brush method is of prime signifi-
cance as in the dyeing of seal, and seal imitations on musk-
rat and coney, enormous quantities of furs being dyed in
this fashion. In the majority of imitations dyed, both the
brush and the dip methods must be used.
Figure 19 illustrates the various types of brushes which
are used at the present time for the application of the dye
by the brush method. Each brush has a specific purpose
and use. (The procedure in brush dyeing is somewhat as
follows. The skins, after being properly treated, that is,
killed, and mordanted, are placed on a table, or work-bench,
hair-side up. Then by means of a brush which is adapted
to the nature and requirements of the particular fur, the
solution is brushed on in the direction of the fall of the hair,
occasionally beating gently with the brush so as to cause
the dye to penetrate to the desired depth. Considerable
skill and care must be exercised in this operation as it is
rather easy to force the dye down further than is wanted,
and in some cases the leather or the roots of the hair may
be affected. The skin having received its coat of dye, is
then dried and finished!) if no other dyeing processes are to
be applied. Frequently, with certain types of dyes, several
applications of color are necessary, and these are brushed
100
GENERAL METHODS
on as the first one, drying each time. ^Then, on the other
hand, the skin may receive a dyeing in the bath by dipping,
and for this also, the fur is first dried after the brush dyeing.
Quite recently, owing to the great quantities of furs
which are being dyed as seal imitations, chiefly by the brush
method, although the dip method is used in conjunction
with it, machines have been invented to replace the hand
brush, and the dye is now applied mechanically. Machines
FIG. 19. BRUSHES USED IN FUR DYEING BY THE BRUSH METHOD.
for this purpose are by no means new, there being records
of inventions almost a score of years past, but they did not
achieve much success. Brush-dyeing machines, to be effi-
cient, must be designed to suit the needs of the particular
type of fur to be dyed, otherwise there will be a great lack
of uniformity in the dyed skins, a condition which cannot
occur when the dye is brushed on by hand brushes. Fig-
ure 20A and B shows diagramatically, machines invented
within the past few years, which are used to dye mechani-
cally furs by the brush process.
101
FIG. 20. TYPES OF MACHINES FOR DYEING FURS BY THE BRUSH METHOD.
A. (U. S. Patent 1,225,447.) B. (U. S. Patent 1,343,355.)
102
GENERAL METHODS
( For the dipping process, ^the dye solution is prepared in
vats, or liquid-tight drums, or in some instances in paddle
arrangements. The skins are placed in the dye-bath, and
the dyeing operation proceeds without any difficulty. After
the proper shade is obtained, the furs are removed, washed
free of excess dye, dried and finished./ The dipping method
FIG. 21. DRUM FOR WORKING WITH LIQUIDS.
(Turner Tanning Machinery Co., Peabody, Mass.)
is employed where a single shade is to be dyed on the
as the production of blacks on lambs. But in most cases,
the dyeing in the bath is supplemented by the application \
of a coat of dye by the brush to the upper part of the hair,y
the color being usually a darker shade than the ground
dyeing. Thus, for example, in the dyeing of imitation sable
on kolinsky or a similar fur, the skins are first dyed the
relatively light color of the under-hair by the dip process,
then the dark stripe effect is brushed on.
103
FUR DRESSING AND FUR DYEING
The blending of sables, martens, chinchillas or other rare
furs, is not done in the same manner as with other furs,
because each skin requires individual attention and a long
and careful treatment. The dye solution is applied by
means of very fine brushes or sometimes feathers, to the
extreme tips of the hair, until the proper degree of color
intensity is obtained. The time, labor, and skill necessary
for this sort of work are warranted only in the case of the
FIG. 22. DEVICE FOR CONVEYING SKINS.
(Turner Tanning Machinery Co., Peabody, Mass.)
highest-priced furs, and the blendings are so excellent as
to defy detection, except by experts.
After the furs have gone through all the operations re-
quired by the processes of killing, mordanting, dyeing and
washing, they are ready to be dried and finished. The pro-
cedure is quite similar to that employed in fur dressing.
Sometimes the leather side of the skins is brushed with
a strong salt solution before drying, in order to replace some
of the salt which was extracted during the dyeing processes.
In other instances, a light coat of some oily substance is
104
GENERAL METHODS
brushed on, to render the leather soft and flexible after
drying, where there is a possibility of the skins turning out
otherwise. Great care must be exercised in the handling
of the dyed skins to avoid the formation of stains or spots
on the hair, which might ruin the dyeing. As little hand-
ling of the furs as is feasible will reduce any trouble from
this source. In conveying the wet skins from one part of
the plant to another it is desirable to use a device such as
is shown in Fig. 22. For drying, the same machines as
described under Fur Dressing can be used, and similar care
must be taken to avoid overheating or irregularity of dry-
ing. /Drum-cleaning constitutes a very important opera-
tion in the finishing of the skins, the hair receiving a polish,
and the full lustre and brilliancy of the dye being thereby
brought out. Then after caging to remove the sawdust or
sand, the skins are passed over the staking knife, or are
treated in a machine suited for the purpose, to stretch them
and to render them thoroughly soft and flexible. And
therewith is concluded the work of the fur dyer proper,
and the skins are ready to return to the furrier, in whose
hands they undergo the metamorphosis into the fur gar-
ments to be worn chiefly by the feminine portion of
humanity.]
105
CHAPTER X
FUR DYEING
" KILLING " THE FURS
IF dressed furs are treated with a paste or solution of a
dye properly prepared, and at the right temperature,
the hair will show very little tendency to absorb the
coloring matter. Even after prolonged treatment with the
dye, only a small amount will be taken up by the hair,
and in a very irregular fashion. Soft, woolly hair, like that
of lambs and goats will be colored more easily than that
of furs with harder hair, and the under-hair of a fur will
generally have a greater affinity for the dye than the harder
and stiffer top-hair. Moreover, in some parts of the same
fur, the hair will absorb more color than in other parts.
In other words, the hair of furs resists the action of dye
materials to a greater or less degree, depending upon the
character of the fur, and also upon the part of the pelt.
In order to overcome this resistance of the hair, and to
render it uniformly receptive to the coloring substances, the
furs are treated with certain chemical agents, the process
being known technically as " killing."
The origin of the term is obscure, but it is interesting ta
note that in the fur dyeing countries other than the United
States and England, the corresponding expression is used:
in Germany, " toten," and in France " tuer." The explana-
tion of the process is as follows: The surface of the hair is
covered with a fine coat of fatty material which renders the
hair more or less impervious to dye solutions and solu-
tions of other substances which may be used for dyeing
purposes. This fatty coating of the hair cannot be removed
106
"KILLING" THE FURS
by mechanical means, otherwise the hair would have been
freed of it during the dressing operations. Chemical sol-
vents must therefore be resorted to, and naturally alkaline
materials areTlised, these being usually cheapest and alsu
mostlsffective in their dissolving ft/t.mn pp fatty substances.
Alcohol, ether, benzine, and other similar liquids also serve
as killing agents on furs, since they too, are fat solvents.
In all these cases, the fatty substance on the hair is dis-
solved away, and the protective coat which previously ren-
dered the hair impervious to the dye, is now removed.
There are certain chemicals however, which normally do
not dissolve substances of a fatty nature, but are strongly
oxidizing, such as peroxide of hydrogen, hypochlorites,
permanganates, perborates, nitric acid, etc., and exert a
killing action when they are applied to the hair, in that
the hair is made capable of taking up the dye from its solu-
tions. In this case the killing can hardly be said to be due
to a degreasing process. The fact that killing can be
brought about with other substances than alkalies or fat
solvents, has led to the belief on the part of some investi-
gators in this field that killing is more than a degreasing
operation, although the removal of the fatty material of
the hair undoubtedly takes place. Some authorities con-
sider that the killing process changes the pigment of the
hair, which thereby becomes more receptive to the dye.
It is quite possible that some such change in the structure
of the hair fibre does take place, the surface of the hair be-
coming slightly roughened, and therefore more capable of
fixing the coloring matter. The question is still an open
one, and since no conclusive researches have been made
as yet, it will be assumed that killing is simply a degreasing
process, inasmuch as the modern practise is based on this
supposition, and very satisfactory results are obtained.
:Air~accoTrrrt of the historical development of the killing
process brings out many interesting and enlightening facts,
so it will be given here briefly. One of the first substances
107
FUR DRESSING AND FUR DYEING
used for killing, or degr easing the hair of furs, was de-
composing urine. Urine contains about 2% of urea which
gradually changes to salts of ammonia, and in the presence
of the air, largely to ammonium carbonate. This substance
has a weak alkaline action, but sufficiently effective to be
used for killing the hair of certain types of furs. Woolly
furs, such as those derived from the various kinds of sheep
and goats, were degreased with stale urine, the skins being
washed in this, and then rinsed in water. The fat was
emulsified by the ammonium carbonate present, and could
thus be easily removed. For other furs, a stronger mixture
was necessary. An example of a killing formula used on
wolf, skunk and raccoon, which were to be dyed black, is the
following :
350 grams beechwood ashes
200 grams unslaked lime
150 grams copper vitriol
100 grams litharge
60 grams salammoniac
40 grams crystallized verdigris
3.5 liters ^ain water
Beechwood ashes were a very important constituent of the
old killing formulas. The reason for that lies in the fact
that beechwood contains a comparatively high percentage
of potassium, which occifts in the ashes of the burned wood
as potassium carbonate, or potash. The ashes alone were
frequently used, being applied in the form of a paste, which
in some instances had an advantage over a solution, in that
the killing could be limited to certain parts of the skin
where it was more desired than in other parts. By extract-
ing the wood ashes with hot water, and evaporating the
clear solution to dryness, potash could be obtained,
which was considerably stronger than the original ashes.
Next in importance for the killing was unslaked lime. This
substance was also often used by itself, being first slaked
108
" KILLING" THE FURS
with water, and using the milk of lime thus formed, after
cooling. Salammoniac, although a salt, and consequently
without any killing action, in contact with the beech wood
ashes or the lime in solution or paste, liberated ammonia
slowly, and so also acted as a degreasing agent. The other
chemicals in the formula took no part in the actual killing
of the hair, but acted either as mordant materials or as
mineral dyes. The copper salts, in this mixture present in
two forms, as sulphate in copper vitriol, and as acetate in
the verdigris, were important constituents of the dye for-
mula, being essential to the production of the proper shade.
These substances properly had no place in the killing for-
mula. The litharge, also was not a killing agent, but in the
presence of the alkaline materials of the killing mixture,
it gradually combined with the sulphur contained in the
hair, forming lead sulphide, and thereby darkening the
color of the hair. In this case, the metallic compound acted,
not as a mordant, but as a mineral dye. The mixture was
applied to the hair by means of a brush, the skins let lie
for some time, then dried, brushed and beaten. Many
applications were usually necessary to sufficiently degrease
the hair. Inasmuch as the killing paste was prepared by
mixing the constituents together, and then was brushed on
at the comparatively low temperatures which the proper
protection of the hair required, it is questionable whether
some of the metal compounds were even enabled to act as
described above as mordant or dye. In spite of the trouble
and considerable time required in working with such a
killing formula to obtain the hair in the desired condition
for dyeing, the use of such a mixture nevertheless possessed
the advantage that the hair was only very slowly and
gradually acted upon, and so the gloss was preserved. The
action of strong alkaline substances acting quickly is more
or less detrimental to keeping the gloss of the hair, while
the slow action of the weak alkaline paste of the old formu-
las, and the gradual formation of a protective metal film on
109
FUR DRESSING AND FUR DYEING
the surface of the hair, rendered the hair suitably receptive
to the dye which was subsequently applied, without in any
measure affecting the lustre of the hair.
It would be needless to describe or discuss any more of
the old killing formulas, for the principle involved was the
same in all cases, there being usually a slight variation in
the content of metallic salts, beechwood ashes and unslaked
lime being constituents of the great majority of the mix-
tures used. Modern killing processes employ substances
quite similar to those of the old formulas, the operations,
however, being much less laborious and less time-consum-
ing, and the cheap, pure products which chemical science
has been able to develop being used in place of the crude
products crudely obtained from natural sources. The chem-
icals used at the present time for killing furs, are chiefly
ammonia, soda ash, caustic soda, and caustic lime. The
choice of the killing agent depends upon the nature of
the fur, the hair of some furs being sufficiently killed by
treatment with weak alkalies, while in other furs the hair
may require stronger treatment. The ability of the hair
of a particular fur to withstand the action of the different
alkaline substances must be taken into consideration, there
being a great divergence in this regard among the different
classes of furs. Raccoon, for example, is not appreciably
affected by a solution of caustic soda of 5 degrees Beaume,
while some wolf hair cannot withstand the action of a solu-
tion of soda ash of less than 1 degree Beaume. Frequently
much stronger alkalies are necessary to kill the top-
hair than the under-hair, so this accomplished by treat-
ing the skins in a solution which is suited to kill the
under-hair, and subsequently the top-hair is treated with
a stronger solution, this being applied by the brush
method.
Uniformity of action of the killing material on all parts
of the skin, and on all the skins of a given lot, is absolutely
essential to obtaining satisfactory results in dyeing. And
110
"KILLING" THE FURS
it is by no means a simple matter to get such uniformity,
considering the numerous factors that must be taken into
account. Any operation involving the immersion of the
skins in solutions or even hi water alone, has an effect on
the leather side of the skin, inasmuch as some of the tan-
ning materials may be extracted. The application of some
substance of a fatty nature to a great degree prevents this,
and the skin can be killed, mordanted and dyed, and then
come out soft and flexible. But the great majority of
substances of a fatty nature are affected by alkalies, and so
when the skins are being killed, the action of the alkaline
materials would be upon the fat contained in the leather
as well as that upon the hair. As a result the hair may
not be sufficiently killed, and so give uneven dyeings sub-
sequently. Either a certain excess of the killing chemical
must be used, and it would be very difficult to ascertain what
quantity would suffice, or the killing action must be
prolonged; but best of all, in oiling the skins, an inert
mineral oil should be used, since it is wholly unaffected by
alkalies.
Skins may be killed by the brush process or the dip proc-
ess, or by both. For brush killing, the stronger alkalies
like lime and caustic soda are used, the solution being ap-
plied to the top-hair with a suitable brush, and the skins
allowed to remain hah- to hair for the necessary length of
time, after which they are treated further as skins killed
by the dip process. By this latter process, the furs are
immersed in a solution of the desired killing agent in a vat,
or drum, or other appropriate device which will permit of
uniform action of the alkali on the hair of all the skins.
After remaining in the solution the required length of time,
the skins are drained, and rinsed in fresh water, and then
entered into a weak solution of an acid in order to neutralize
any remaining alkali, it being easier to wash out acid than
alkali. The furs are then washed thoroughly in clear water,
preferably running water, to remove the last traces of acid.
Ill
FUR DRESSING AND FUR DYEING
The skins are then drained and hydro-extracted, or pressed,
and are then ready for the subsequent operations of mor-
danting and dyeing.
KILLING WITH SODA
Soda is sodium carbonate, which is produced commer-
cially in a very pure state in several different forms, the
chief being sal soda, which is crystallized sodium carbonate,
containing about 37% of actual soda; and soda ash, or
calcined soda, which is anhydrous sodium carbonate. The
latter is the variety most commonly used.
10 grams soda ash are dissolved in
1 liter of water at 25-30 C.
The skins are immersed for 2-3 hours, after which they are
rinsed and treated with
10 grams acetic acid dissolved in
1 liter of water.
The skins are again thoroughly washed, and then hydro-
extracted.
KILLING WITH LIME
Lime, calcium oxide, forms a white, amorphous, porous
substance, which readily takes up water, giving calcium
hydroxide, or slaked lime. Only the best grades of lime
should be used, as it is very frequently contaminated with
calcium carbonate and other inert materials.
10 grams of lime are dissolved in
1 liter of water.
The skins are entered, and allowed to remain for a period
of time which varies according to the nature of the fur.
During the killing, the solution must be agitated, in order
to evenly distribute the milk of lime, which has a tendency
112
" KILLING" THE FURS
to settle out. After rinsing, the skins are " soured," by
treating with weak acetic acid solution, then thoroughly
washed, and drained.
KILLING WITH CAUSTIC SODA
Caustic soda is used only on furs the hair of which is
very hard and resistant to killing. Usually it is applied
by the brush process, but in some instances, the dip method
must be used. In order to reduce as far as possible, the
action of the caustic soda on the leather, the weakest per-
missible solutions are used, increasing the time of treat-
ment, if necessary. Caustic soda is a white, crystalline
substance, occurring in commerce in lumps, but more con-
veniently in a solution of 40 degrees Beaume, containing
35% of caustic soda. Various quantities, ranging from 4
to 25 grams of this solution per liter of water are taken,
according to the character of the fur, and the skins treated
for 2-3 hours, although weaker solutions may be used, and
increasing the duration of the killing. By keeping the
solution in motion, by means of a stirrer or any other
method of agitation, the best results are obtained. After
the skins are sufficiently killed, they are soured, and washed
as by the other killing methods.
Where the nature of the hair of the fur is such that the
top-hair and the under-hair require different killing treat-
ments, the skins are first killed by the dip. process, with
an alkali suited to kill the under-hair, then a brush killing
with a stronger alkali is applied to the top-hair. The
subsequent treatments are the same as for usual dip-killing
methods.
113
CHAPTER XI
FUR DYEING
MORDANTS
THE hair of furs has the peculiar quality of fixing
the oxides or hydroxides of certain metals from
dilute solutions of their salts. Advantage is taken
of this property to mordant the furs, that is, to cause a cer-
tain amount of the metallic oxide or hydroxide to be perma-
nently absorbed by the fibres. The term mordant comes
from the French word " mordre," meaning to bite, it being
formerly considered that the purpose of a mordant was to at-
tack the surface of the hair in such a way as to permit the
dye to be more easily absorbed. In fact, killing mixtures,
which were intended for this same object, used to contain
the various chemicals which have a mordanting action,
in addition to the alkaline constituents. The mordants
were not applied as such, but always as killing materials.
It was later realized, however, that the mordant was instru-
mental in the production of the color itself.
Mordanting may be considered as having a two-fold
object: first, to help fix the dye on the fibre in a more
permanent fashion, thus rendering the dyeings faster; and
secondly, to help obtain certain shades of color, as the
various mordants produce different shades with any given
dye. Some classes of dyes can be applied to furs without
the use of mordants, but other types are taken up only in
a very loose manner, being easily washed out from the
hair with water, and it is only when such dyes are brought
on to the hair in the form of a metallic compound, pro-
114
MORDANTS
ducing what is known as a lake/' that really fast dyeings
are obtained with them. The substances which are used for
mordanting the hair are certain metallic compounds, but
not all metallic salts which are used in dyeing are mordants.
Sometimes such a compound is employed to develop the
color of the dyeing by after-treatment, as in the case of
after-chroming, the action of the metallic salt being directed
only to the dye, and is not fixed by the fibre as a mordant
must be. In order for a metallic compound to act as a
true mordant, it must be fixed by the hair, and it must
combine with the dye, thus forming a sort of connecting
link between the dye and the hair. It is not absolutely
essential that the mordant be applied first, although this
is the customary and commonest practise. There are three
ways by which the mordants can be fixed on the fur hair:
First, by the absorption of the metallic oxide or hydroxide
from a solution of the mordant prior to the dyeing; second,
the mordant may be fixed on the fibre at the same time
as the dye; and third, the mordant may be applied after
the fur has been treated with the dye. The last two meth-
ods will be discussed in connection with the dyes, as they
are special cases.
The salts of metals which are comparatively easily dis-
sociated in water, with the formation of insoluble oxides
or hydroxides, are most applicable as mordants for furs,
and among them are compounds of aluminum, iron, chro-
mium, copper and tin. The constituents of the hair seem
to bring about the dissociation of the metallic salt, and
the oxide or hydroxide as the case may be, is absorbed and
firmly fixed by the hair. Just what the manner and nature
of this fixation are, is still uncertain. It is supposed that
chemical combination takes place between the hair . and
the metal. The course of this process may, as far as is
known, be described as follows, taking, for example, the
case of chromium sulphate: In dilute solution, this com-
pound gradually dissociates first into its basic salts, and
115
FUR DRESSING AND FUR DYEING
finally into the hydroxide, the breaking up of the neutral
salt being induced by the presence of the fur-hair.
Cr 2 (S0 4 ) 3 + 2H 2 = Cr 2 (S0 4 ) 2 (OH) 2 + H 2 SO 4
chromium water first basic sulphuric
sulphate chrome salt acid
Cr 2 (S0 4 ) 2 (OH) 2 + 2H 2 O = Cr 2 (S0 4 )(OH) 4 + H 2 S0 4
second basic
chrome salt
Cr 2 (SO 4 )(OH) 4 + 2H 2 = O 2 (OH) 6 + H 2 S0 4
chromium
hydroxide
These reactions take place within the fibre, after the hair
has been impregnated with the solution of the neutral salt,
and when the compound has been rendered completely
basic, in other words has reached the form of the hydroxide,
it is supposed to combine with the acid groups contained in
the hair substance, forming thus some complex, insoluble
organic compound of the metal within the hair. Accord-
ing to some authorities the mordant is supposed to be
present in the hair simply as the hydroxide, being tena-
ciously held by some physical means. The facts seem to
indicate, however, that the metal is actually combined in
some chemical way with the hair. For, if the mordant were
present as hydroxide, then on white hair it would show
the color of the hydroxide, which it does not. The same
facts obtain with regard to other metals.
In order for the hair to be properly mordanted, it is nec-
essary that the metallic compound which is taken up by
the hair be held in such a manner that the mordant cannot
be removed by water or even dilute acids or alkalies. Salts
which dissociate too readily produce mordants which are
only superficially precipitated on the hair and subsequently
come off. Usually some substance is added to the solution
of the salt to cause slower and more even dissociation of
the salt, so that the hair substance can be quite saturated
with the metallic compound before any insoluble precipi-
116
MORDANTS
tate is formed. Dilute sulphuric acid, organic acids like
acetic and lactic, and cream of tartar are used to facilitate
the uniform absorption of the mordant salt by the hair.
When the skins are mordanted before dyeing, they are
immersed for 6 to 24 hours in a solution containing 1 to
20 grams of the metallic salts per liter of water, together
with the corresponding quantity of the assistant chemical.
The skins should be so entered into the mordant solution
that the hair is uniformly in contact with the solution, and
all the skins so that they are acted upon alike. Machinery
such as is used for killing is suitable for mordanting also.
The duration of the mordanting, and the concentration of
the solutions are varied according to the depth of shade
required, and also according to the nature of the dye to be
employed. By suitably combining several mordants a con-
siderable range of colors can be obtained with a single dye.
The various chemicals used as mordants are essentially
the same no matter for which class of dyes they are used,
there being only slight differences in the concentrations of
the solutions, the manner of application of the mordants
being practically the same. It is interesting to note that
with the exception of chromium compounds, which are of
comparatively recent adoption as mordants, all the chemi-
cals now used for mordants were employed by the earliest
masters of the art of fur dyeing. While some of the formu-
las used by those dyers display a lack of appreciation of
the true action and function of the mordanting chemicals,
yet it is quite remarkable that they chose, in spite of their
limited knowledge of chemical processes and phenomena,
just those materials which do act as mordants if prop-
erly applied. The most important metallic compounds for
mordanting furs at the present time are salts of aluminum,
iron (ferrous), copper, tin and chromium (as well as chro-
mates and bichromates). The compounds of the metals
with organic acids such as acetic acid are preferable, being
more easily dissociated, and also leaving in solution an acid
117
FUR DRESSING AND FUR DYEING
which is less injurious to the fur than a mineral acid. How-
ever, sulphates and other salts of the metals are also used ex-
tensively, inasmuch as they are cheaper than the organic
salts.
ALUMINUM MORDANTS
Chief among the aluminum mordants are the various
kinds of alum, which is a double sulphate of aluminum and
an alkali such as sodium, potassium or ammonium. All
these salts except that of sodium, form large, colorless,
octahedral crystals, and are soluble in about 10 parts of
cold water, and J part of hot water. Sodium alum is even
more easily soluble, but on account of the difficulty of
obtaining it in crystalline form, it is little used. The com-
mon commercial alum is the potassium aluminum sulphate.
Recently, aluminum sulphate has to a large extent re-
placed alum for mordanting purposes, because it can be
obtained very cheaply in pure form, and it contains a
greater amount of active aluminum compound than does
alum. Only the iron-free salt, however, may be used for
the needs of fur dyeing.
Aluminum acetate also finds extensive application as a
mordant in fur dyeing, and while somewhat more expensive
than the alum or aluminum sulphate, it has the advantage
over these compounds of being combined with an organic
acid, which is preferable when the action on the hair and
leather is considered. Aluminum acetate can be obtained
in the market in the form of a solution of 10 degrees
Beaume, but can also be prepared very easily as follows :
665 grams pure aluminum sulphate, or
948 grams potassium alum, are dissolved in
1 liter of hot water.
1137 grams of lead acetate (sugar of lead) are also
dissolved in
1 liter of hot water.
118
MORDANTS
The two solutions are mixed, and thoroughly stirred. A
heavy white precipitate forms, which is filtered off, and dis-
carded after the solution has cooled. The aluminum ace-
tate is contained in the filtrate, and the solution is brought
to a density of 10 degrees Beaume by the addition of water,
if necessary, and is preserved for use in this form.
IRON MORDANTS
Ferrous sulphate, iron vitriol, or copperas, as it is com-
monly known, forms pale green crystals, which on exposure
to air lose water, and crumble down to a white powder. It
is very soluble in both cold and hot water, but the solutions
oxidize very rapidly, turning yellowish, and should there-
fore be used immediately. Care must be taken that a good
quality of iron vitriol be used for the mordant, otherwise
very unsatisfactory results will be obtained.
Ferrous acetate is prepared in a manner similar to the
aluminum acetate, and is occasionally employed instead of
the ferrous sulphate. Inasmuch, however, as the solution
of ferrous acetate is very easily oxidizable when exposed to
the air, a more stable form is used, and this comes on the
market as iron pyrolignite or iron liquor. This can be
prepared by dissolving iron in crude acetic or pyroligneous
acid, or by treating a solution of iron sulphate with calcium
pyrolignite. Iron liquor is really a solution of ferrous ace-
tate that contains certain organic impurities which prevent,
or rather, considerably retard the oxidation of the iron salt,
but which in no way interfere with its mordanting proper-
ties. The commercial product can be had in various con-
centrations, but 10 degrees Beaume is the most usual and
most convenient.
COPPER MORDANTS
The most important copper salts used in fur dyeing
processes are copper sulphate, or blue vitriol, occurring in
119
FUR DRESSING AND FUR DYEING
large blue crystals, very soluble in cold and in hot water;
and copper acetate, which is formed by treating a solution
of copper sulphate with a solution of the requisite quantity
of lead acetate. Copper acetate can also be obtained in
the form of blue-green crystals, very soluble in water, the
solution becoming turbid on prolonged heating, due to the
formation of a greenish basic copper acetate. This insol-
uble compound is known commonly as verdigris, although
it is not usually produced in the manner mentioned. Nu-
merous fur dyeing formulas contain verdigris, but inasmuch
as the basic copper acetate is insoluble and thus incapable
of reacting with any of the substances used in dyeing, it is
assumed that the soluble normal copper acetate was meant,
for this compound is also sometimes called verdigris.
In addition, there must be mentioned here a compound
which formerly found extensive use in fur dyeing. This
is a double salt of copper and iron, analogous to alum, fer-
rous copper sulphate, known as blue salt. It is very seldom
used at the present time, being more effectively replaced
by other substances.
CHROMIUM MORDANTS
The typical chromium mordant is chrome alum, which is
a potassium or ammonium chromium sulphate, constituted
just like the aluminum alums, and forming crystals like
these. More frequently used, nevertheless, than the chrome
alum, is chromium acetate, which is prepared from it,
either by treating a solution of the chrome alum with a
solution of lead acetate, or in the following manner:
50 grams of chrome alum are dissolved in
500 cubic centimeters of boiling water. To this
is added
15 grams of 20% ammonia, diluted with 15
grams of water.
120
MORDANTS
The precipitate which forms is filtered off, and preserved,
the filtrate being discarded. After thoroughly washing
the residue on the filter it is dissolved in dilute acetic acid,
heating if necessary, to effect solution.
Other chromium compounds of an entirely different type
are also used in fur dyeing, these being chromates and
bichromates, the latter finding greater application than the
former. Sodium bichromate is the salt most usually em-
ployed. This forms orange-red crystals which are very
soluble in water, and in addition to its use as a mordant it
also serves as an oxidizing agent for developing or fixing
certain dyes on furs.
TIN MORDANTS
Compounds of tin find only limited application in fur-
dyeing, the only one of importance being tin salts, stannous
chloride, which occurs in the form of white, hygroscopic
crystals, which must be preserved in closed vessels. It is
very soluble, but in dilute solutions it readily forms a basic
salt, so stannous chloride is usually used in very concen-
trated solutions.
ALKALINE MORDANTS
After the furs have been treated with the solution of
some alkali for the purpose of killing the hair, they are
always passed through a slightly acidulated bath to re-
move any alkali which may still be adhering. This opera-
tion must always be gone through before the skins can
be mordanted or dyed, for if it were neglected, very uneven
and uncertain results would be obtained. This process,
however, entails the expenditure of no small amount of
time, labor and chemicals when large lots of skins are being
handled. In order to eliminate this extra step of " souring "
.between killing and mordanting or dyeing, it has been pro-
121
FUR DRESSING AND FUR DYEING
posed to use alkaline mordants which combine the killing
and mordanting functions, and accomplish these two proc-
esses at the same time. The advantages of employing
such mordants are easily apparent. Cumbersome manip-
ulation and handling of the skins, with the attendant con-
sumption of much time and labor are reduced to a mini-
mum, and besides there is no needless waste of chemicals as
is the case in the ordinary methods of killing the furs.
The principle of alkaline mordants is not a strictly new
one. If it be remembered that the old killing formulas used
by the fur dyers of an earlier age, contained metallic salts
with mordanting properties in addition to the alkaline sub-
stances, which alone were effective as killing agents, it
would seem that the suggested alkaline mordants were
merely a revival in modified form of the old processes. This
is undoubtedly true in a large measure, for the killing mix-
tures which the old masters used certainly embodied the
fundamental principle of simultaneous killing and mor-
danting, although it was not recognized at that time.
Modern alkaline mordants have therefore been devised
which can be employed for killing and mordanting furs at
the same time. They are prepared as follows :
ALKALINE ALUMINUM MORDANT
250 grams of potassium alum are dissolved in
1 liter of boiling water. To this solution
is added
300 grams of soda ash, previously dissolved in
750 c.c. of water, and the resulting precipitate is
filtered off, washed and pressed, and then dissolved in a
solution of 65 grams of caustic soda in 1 liter of water.
122
MORDANTS
ALKALINE CHROMIUM MORDANT
250 c.c. of chrome acetate mordant of 20 de-
grees Beaume
320 c.c. of caustic soda solution of 38 degrees
Beaume (32.5%)
10 c.c. of glycerine 30 degrees Beaume (95%)
The solution of these substances is brought up to a volume
of 1 liter by the addition of 420 c.c. of water.
ALKALINE IRON MORDANT
138 grams ferrous sulphate are dissolved in
362 c.c. of warm water. Cool and add
25 c.c. of glycerine. Then slowly and carefully
add
25.5 c.c. of concentrated ammonia, taking care
that no precipitate forms.
While these alkaline mordants seem to have much in
their favor, there are certain possible objectionable features
which must be considered. The solutions of the mordants
are generally very alkaline, and not every fur can withstand
more than a limited quantity of alkaline substance for
longer than a comparatively short time. Suitable mordant-
ing usually requires a longer time than killing does, so
with the use of the alkaline mordant, if the skins remain
in the solution until sufficiently killed, they may be in-
sufficiently mordanted, while if the furs are treated long
enough to be properly mordanted, the hair may have been
over-killed. However, the idea of the alkaline mordant is
a good one, and it is only a matter of time and patient,
scientific experimentation when the difficulties of the
method will be eliminated, and a much-desired process will
become a practical realization.
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FUR DRESSING AND FUR DYEING
The general methods for applying the various mordants
of all sorts follow closely the procedure adopted for the
killing formulas, and similar precautions must be observed,
in order to obtain consistently uniform results. With the
exercise of care, there is little reason for the mordanting
operations to go wrong.
After proper treatment of the skins in the mordants,
they are removed and drained off, then rinsed lightly in
running water to remove the excess of mordant liquor,
after which they can be directly entered into the dye bath.
If it is not feasible to dye the mordanted skins at once,
as is often the case, the skins are kept moist, and under
no circumstances allowed to dry.
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CHAPTER XII
FUR DYEING
MINERAL COLORS USED ON FURS
BEFORE the introduction of the fur dyes now used,
certain inorganic chemical substances were em-
ployed in addition to the vegetable dyes, for the
production of colors on furs. Even to this day such mate-
rials are used to obtain certain effects in special instances.
The idea of employing mineral chemicals undoubtedly ori-
ginated in the textile-dyeing industry, which at one time
was dependent to an appreciable extent on mineral sub-
stances for the production of certain fast shades. Com-
pounds of iron, lead, manganese, also of copper, cobalt and
nickel were all used for dyeing, either singly or in various
combinations. In the application on furs, the brush
method was the only one practicable, as the skins
would have been ruined by dipping them into solutions of
these chemicals in the concentrations necessary for dyeing.
The dyeing of furs with mineral colors involves the pre-
cipitation on the fibre in a more or less permanent form
of the sulphide, oxide or other insoluble compound of a
metal, and can be brought about in several ways. By
what is known as double decomposition, that is, by the use
of two solutions successively applied, the ingredient of one
causing a precipitate to form when in contact with the
constituent of the second, the color is produced on the hair.
Another method is to use solutions of chemicals which
decompose on contact with the hair, forming an insoluble
compound. In the first method the hair is alternately
treated with the two solutions of the requisite chemicals,
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FUR DRESSING AND FUR DYEING
drying between each brushing, the process being repeated
until the desired shade is obtained. The second method
merely requires the solution of the chemical to be applied
to the hair, which is then dried, the color forming by itself.
One of the most important of the mineral dyes, and
which is occasionally used to this day, is lead sulphide,
formed by the double decomposition method by precipita-
ting a soluble lead salt with ammonium sulphide, or any
other alkaline sulphide. By simply brushing an aqueous
solution of lead acetate, also known as sugar of lead, on a
white fur such as white hare or rabbit, a light, brownish
coloration is obtained due to the combination of the lead
with the sulphur of the hair. If the lead solution is care-
fully applied several times on this type of fur, until a
sufficiently dark color is produced, it is possible to get a
fairly good imitation of the stone marten. The brown color
is very fast, being actually formed within the hair. In
most cases, however, for dyeing lead sulphide shades
it is necessary to use the two solutions. Thus the pale
greyish or slightly brownish-grey shades of the lynx can
be reproduced on white rabbit or hare by this process. A
solution containing 60 grams of lead acetate per liter of
-water is brushed on to the hair of the fur which has pre-
viously been killed in the usual manner, and the hair is
then dried. A solution of 50 grams of ammonium sulphide
per liter of water is next brushed on, and the fur again
dried. Care must be exercised in handling the ammonium
sulphide as it is a very malodorous liquid, the fumes of
which are poisonous when inhaled. The alternate brush-
ings are repeated until the desired depth of shade is ob-
tained. A very dark brown, approaching a black can be
obtained in this way. This color can be used for the
production of certain attractive effects. By brushing over
the tips of the hair, which has previously been dyed a
dark brown by means of the lead sulphide color, with a
dilute solution of hydrochloric acid, or with peroxide of
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MINERAL COLORS USED ON FURS
hydrogen, the hair will become white in the parts so treated,
due to the formation of lead chloride or lead sulphate,
respectively. Thus white tipped furs can be obtained, but
the process is applicable only when the furs have been
dyed by the lead sulphide method.
Potassium permanganate is occasionally used to produce
dyeings of a brown shade on furs. Considerable care has
to be taken in applying this substance, as it is possible to
affect the hair. The strength of the solution must be va-
ried according as the hair to be dyed is weak or strong.
A cold solution of 10 to 20 grams of potassium permanga-
nate per liter of water is brushed on to the hair, which is
then dried. A brown precipitate of manganese is formed
on the hair after a short time, and the process is repeated
until the required shade is obtained. For furs with harder
hair, stronger solutions can be used. The dyeing is very
fast, but it is seldom used, cheaper and better shades being
obtained in other ways. Spotted white effects can be pro-
duced on the brown dyeing with permanganate of potash
by applying a solution of sodium bisulphite, the brown
color being dissolved by this chemical.
The compounds of other metals, such as iron, copper,
cobalt and nickel are not used in practise as the dyeings
are not fast, and can be better produced in other ways.
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CHAPTER XIII
FUR DYEING
VEGETABLE DYES
WITH the exception of the few shades which could
be produced solely by means of coloring matters
of a chemical character, all dyeings on furs up to
about thirty years ago were made with dye substances
obtained from the vegetable kingdom, either alone, or in
conjunction with the aforementioned mineral colors. The
colors of vegetable origin used in comparatively recent
times were mainly extracts of the wood of certain trees; so
the name " wood dyes " has come to be applied generally
to the dyes of this class. The use of the vegetable or nat-
ural dyes on furs dates back to quite ancient times, as
frequent allusions and descriptions in Biblical and other
contemporaneous literature testify. There are numerous
pictures on monuments and tablets illustrating the dyeing
of furs among the ancient Egyptians, the evidence indicat-
ing that the juice of certain berries, and extracts of certain
leaves, were used for the purpose. At a later period, in the
Roman era, henna, which was used over two thousand years
ago as to-day for the beautification of the hair of women, was
also used to color fur skins. The instances cited here are
merely of scientific and historical interest, and are not of
practical importance as far as fur dyeing methods, are
concerned.
It was not until many centuries later that the dyeing of
furs took on the aspects of a commercial art, and the sub-
stances then employed were chiefly tannin-containing ma-
terials such as gall-nuts and sumach, which in conjuction
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VEGETABLE DYES
with certain metallic salts, particularly those of iron, were
capable of producing dark shades. The use of iron com-
pounds to form dark grey or black colors on leather tanned
by means of the tannins, had been common for a long
time, and it was natural that fur dyers should try to pro-
duce such shades on furs in a similar fashion. The use
of the iron-tannin compound as a dye proved to be very
effective, and to this day the production of blacks by means
of the vegetable coloring matters has as a basis an iron-
tannate. A formula in common use in the latter seven-
teenth and the eighteenth centuries for producing black
shades on furs, is the following:
Lime water 1117 parts
Gall-nuts 1500 "
Litharge 500
Salammoniac 65
Alum 128 "
Verdigris 64 "
Antimony 64
Minium 32 "
Iron filings 128
Green copperas 384
All these substances except the gall-nuts, the copperas and
half the lime water were boiled up in a cauldron ; then the
gall-nuts and the copperas were placed in a bucket and the
contents of the cauldron poured in, and the rest of the lime
water added. The mixture was stirred up, allowed to settle
for an hour, and when cool, was ready to be applied by
the brush method. For dyeing by the dip process, a similar
mixture was used, only considerably diluted with water.
A study of the formula discloses the fact that in it are
combined killing and mordanting substances as well as
dyeing materials. The lime water, in conjunction with the
salammoniac serves as a killing agent, the verdigris, cop-
129
FUR DRESSING AND FUR DYEING
peras and alum are mordants, while the litharge and the
minium, both compounds of lead, could possibly act as
mineral dyes, and the iron filings and the antimony took
virtually no part at all in the dyeing, except, perhaps to
act in a mechanical way.
The formulas for other shades were made up along sim-
ilar lines, the chief constituent of vegetable nature being
either gall-nuts, sumach, or both. A mixture for a chestnut
brown, for example, contained gall-nuts, sumach, and the
various other mineral constituents as in the black dye,
litharge, alum, copperas, verdigris, salammoniac, antimony,
and in addition, red lead and white lead. It is evident in
both these instances that the shade obtained was as much
the result of mineral dyeing as of vegetable dyeing.
The discovery of America introduced into Europe many
new dye substances, chiefly wood extracts such as logwood
and Brazilwood, but it was not until the nineteenth cen-
tury that these materials found their way into the dye
formulas of the fur dyer. Most of the processes used in
the dyeing of furs were adaptations of methods employed
in silk dyeing, the silk fibre being considered as most nearly
approaching fur-hair in nature and characteristics. By
devious and circuitous paths the formulas of the silk dyers
reached the fur people, and so, in the middle of the nine-
teenth century, dye mixtures containing the various dye-
woods as well as the tannin-containing substances were in
general use for the dyeing of furs. The following is
a typical recipe of that time for the production of black
on furs like wolf, skunk, raccoon, etc. :
Roasted gall-nuts 1000 parts
Sumach 200 "
Iron mordant 200
Copper vitriol 100 "
Litharge 80 "
Alum 60 "
130
VEGETABLE DYES
Salammoniac 50
Crystallized verdigris 40
French logwood extract 30
Rain water 7000 "
The mixture was boiled up, and after cooling was ready
for application by the brush method, the skins being first
killed by a killing mixture also applied by the brush. The
dye substances in this case are the gall-nuts, sumach and
the logwood extract, with the iron mordant, copper vitriol,
and alum as mordants. For brown shades a similar formula
was used containing Pernambuco wood extract, logwood
extract, quercitron bark, gall-nuts and dragonblood, together
with iron, copper and alum mordants.
Formulas such as the above were mainly empirical, that
is, they were compounded as a result of trial of various
combinations of the constituents, without considering the
nature and quantitative character of the reactions, as long
as the desired shades could be obtained. Such dye mixtures
were frequently found to yield results varying from those
expected or originally obtained, because the effectiveness
of the formulas depended upon the exact duplication in
every detail, of conditions which had given satisfactory
results previously, and it was not always possible to attain
such an accurate reproduction of circumstances, especially
when the fur dyers were quite ignorant of the scientific
relationships of the materials used. So when more light
had been shed on the nature and chemical characteristics
of the vegetable dye substances, formulas like those des-
cribed were no longer employed, although the essential
ingredients were the same in the new processes. Unneces-
sary constituents were eliminated, and proper ones sub-
stituted where it was required, and the quantities of the
materials used were made to conform to the chemical laws
governing the reactions. Since these new formulas were
based on a rational understanding of the constituents and
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FUR DRESSING AND FUR DYEING
their reactions, it is desirable to study the latter briefly,
before further discussing the formulas themselves.
The substances of vegetable origin used in modern fur
dyeing may be grouped into two classes, one, the tannin-
containing materials, and the other, the dyewoods proper.
The most important of the tannins are gall-nuts, sumach
and chestnut extract. Cutch, which also comes under this
class, is more frequently used for the production of brown
shades, so it is grouped with the dyewoods. Among the
latter are logwood, fustic, Brazilwood, quercitron, turmeric,
and several others of less significance.
1. Tannin Materials
First and foremost under this heading are the nutgalls.
These are ball-shaped excrescences produced on certain
plants by the punctures of insects in depositing their eggs.
There are two chief varieties, the European, and the
Chinese. The European galls are formed by the female
gall-wasp which drops an egg in the rind of young branches
of certain oaks. A swelling (the nutgall) is produced, in
which the young insect develops, and from which it finally
escapes by piercing a hole through the shell. Those galls
which are not pierced have a fresh bluish or green color,
are heavy and contain most tannic acid. After the insect
has gone out, the galls are of a lighter, yellowish color,
and also of inferior quality. The best oak-galls are the
Aleppo, and the Turkish or Levant galls, containing 55-
60% of tannic acid, and about 4% of gallic acid. The
Chinese galls are produced by the puncture of a plant-
louse on the leaves and leaf-stalks of a species of sumach,
and not on oaks. The galls are very light, and very rich
in tannic acid, containing often as much as 80%. For
dyeing purposes, nutgalls are usually ground to a powder,
and in some instances they are even roasted first and then
ground.
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VEGETABLE DYES
Sumach consists of the leaves and sometimes of the
small twigs and stems of a species of sumach plant known
as the Rhus coriaria. The Sicilian variety is the finest
commercial quality, with the Virginian ranking next. It
is sold as a powder, but also in the form of the whole or
crushed leaves. The best sumach contains 15-25% of
tannin. Extracts are also manufactured, a liquid extract
of 52 degrees Twaddell, which forms a dark brown, thick
paste ; and a solid extract, formed by evaporating the liquid
extract to dryness.
Chestnut extract is prepared from the wood of the chest-
nut oak, which contains 8-10% of tannin. The solid ex-
tract has a bright, black color, while the liquid extract is
a dark brown paste with a smell like that of burnt sugar.
The tannins all give greyish to black shades with iron
salts, and it is this fact which renders them important for
fur dyeing.
2. Wood dyes
One of the most important of all the natural dye sub-
stances, especially for the production of blacks, is logwood.
The color is really a red, but with the common mordants
it forms blue, violet or black shades. Logwood, or cam-
peachy wood, as it is sometimes called, is the product of a
large tree growing in the West Indies, and Central and South
America. When freshly cut, the wood is practically with-
out color, but when exposed to the air it soon becomes a
dark reddish-brown on the surface. The coloring principle
of logwood is called hematoxylin, which is a colorless sub-
stance when pure, and is of itself incapable of dyeing; but
when it is exposed to the air, especially when moist and in
the presence of some alkaline substance, it is converted into
hematein, which is the real coloring matter of logwood. To
prepare the wood for use, the logs are chipped or rasped,
the chips being heaped up and moistened with, water. Fer-
mentation occurs, and the heaps are frequently turned to
allow free access of air to the wood, and to prevent over-
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FUR DRESSING AND FUR DYEING
heating. As a result of this process, a great part of the
hematoxylin is converted to the hematein. The logwood
may be used for dyeing in this state as chips, but logwood
extracts can now be obtained of a high degree of purity
and are easier to work with. The commercial forms of the
extract, are the liquid of 51 degrees Twaddell, and the
solid extract. Hematein crystals can also be obtained.
All these extracts contain mainly hematein, together
with a small percentage of hematoxylin which is con-
verted to the former during the dyeing process. Log-
wood is never used as a direct dye, but is used to form
color lakes with the various mordants, the following colors
being produced:
Iron mordants give grey to black shades
Copper mordants give green-blue to black shades
Chrome mordants give blue to black shades
Aluminum mordants give violet shades
Tin mordants give purple shades
By combining several of the mordants, any desired shade
of black can be obtained, and if other dyewoods are used
in conjunction with the logwood, the range can be further
increased.
Fustic, yellow-wood, or Cuba wood, as it is variously
called, is obtained from a tree also growing in the West
Indies, Central and South America. It is used either as
wood chips, or as a paste extract of 51 degrees Twaddell,
and occasionally as solid extract. Fustic contains two col-
oring matters, morintannic acid, possessing the character-
istics of a tannin, and which is quite soluble in water, and
morin, which is rather insoluble, and which settles out
from the liquid extract. Fustic is the most important of
the yellow dyes of natural origin, and is used considerably
in fur dyeing with logwood for shading the blacks, or for
producing compound shades. With the usual mordants
fustic gives the following colors:
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VEGETABLE DYES
With iron salts . . dark olive
With copper salts olive
With chrome salts olive-yellow to brownish-
yellow
With aluminum salts . . . yellow
With tin salts bright yellow to orange-
yellow
Brazilwood, or redwood, is the product of a tree found in
Brazil, and exists in several varieties, such as peach wood,
Sapan wood, Lima wood, and Pernambuco wood. They
all yield similar shades with the various mordants, and all
seem to contain the same coloring principle, brasilin, which,
like the hematoxylin, has no dyeing power, but by fermen-
tation and oxidation it is converted to brasilein, corres-
ponding to the formation of hematein. Brazilwood and
the related woods are used either as chips or extract, but
seldom alone, usually in conjunction with other dyewoods.
By combining logwood, fustic and Brazilwood in various
proportions, and by employing suitable mordants, all the
shades required by the fur dyer can easily be produced.
Quercitron is the inner bark of a species of oak (Quercus
tinctoria) found in the United States. It contains two
coloring principles, quercetrin and quercetin. The fresh
decoction of quercitron bark is a transparent dull orange-
red which soon becomes turbid and deposits a yellow
crystalline mass. It is generally used in conjunction with
other dyes.
Cutch is the dried extract obtained from a species of
acacia, the principal varieties being Bombay, Bengal, and
Gambier cutch. It contains two coloring principles, cate-
chin and catechu-tannic acid. Cutch acts as a tannin, and
like other tannins discussed above, can be used for the pro-
duction of grey or black shades with iron mordants. It is
employed chiefly, however, for dyeing browns. Aluminum
salts give with cutch a yellowish-brown, tin salts give a
135
FUR DRESSING AND FUR DYEING
lighter yellow, copperas gives a brownish-grey, and chrome
and copper salts give brown shades.
Turmeric is the underground stem of the curcuma tinc-
toria, the coloring principle being called curcumin. It may
be used as a direct dye, but usually a mordant is used.
Turmeric is sometimes used in place of fustic.
While the tannins can be used alone with an iron mor-
dant for producing greyish to black shades, the dyewoods
alone yield colors which would be too bright to be suitable
for dyeing furs. In order to tone down this brightness, and
to give to the dyeings that greyish undertone which is
characteristic of the natural furs, and which can only be
imitated by means of the iron-tannin compound, it is cus-
tomary to combine the tannins with the wood dyes. The
iron-tannate constitutes the foundation of the color which
gets its intensity, and necessary brilliancy and bloom from
the wood dyes. Moreover, the presence of the iron-tannin
compound helps considerably to increase the fastness of
the dyeing. Furs dyed with the combination of the tan-
nins and the wood dyes obtain an additional tanning treat-
ment which materially improves the quality of the leather,
for not only do the tannin substances exert this tanning
action, but the dyewoods as well, for they are themselves
either of the nature of tannins, or contain a coloring prin-
ciple which is a tannin. It is to the combined effects of
the tannin substances and the dyewoods that furs dyed with
vegetable dyes owe their beauty of color, lustre, naturalness
of shade, permanence of the dyeing, and durability of the
leather. Wood dyeings on furs have for this reason ac-
quired a just renown, but owing to the introduction of the
new kinds of fur dyes, the use of the vegetable dye sub-
stances has been greatly reduced.
The dyes of vegetable origin can be applied to furs by
either the brush method or the dip method, or both, and
since mordants are required with the dyes of this class,
they are applied in one of the three ways mentioned in a
136
VEGETABLE DYES
previous chapter: first, by mordanting before dyeing; sec-
ond, by applying mordant and dye simultaneously ; and
third, by mordanting after the skins have been treated
with the dye.
I. DYEING WITH VEGETABLE DYES BY THE
BRUSH METHOD
The use of the brush method in applying the natural
dyes to furs is limited to a comparatively few kinds of
dyeing, namely to produce special effects on furs, or to give
to the upper-hair of furs a coat of dye different from the
base color. In a quite recent German patent is described
a process for blending a red fox as a silver fox and the
procedure affords a good example of brush dyeing with
preliminary mordanting. The specification is as follows:
" D. R. P. 310, 425 (1918). A process for dyeing red fox
as silver fox. The tanned and dressed skin is first super-
ficially decolorized by applying a dilute mixture of milk of
lime, iron vitriol and alum, with a soft brush so as only
to penetrate the top-hair. Allow to remain for 4-6 hours,
dry, and beat out the dust. A dilute solution of iron vitriol
is brushed on so as only to wet the top-hair, and the skin
is thus allowed to remain moist for 12-24 hours. Then
without drying, a solution of iron vitriol, salammoniac,
litharge, red argol and wood ashes is brushed on cold with
a hard brush so as to penetrate all the hair down to very
near the skin. The skin has now completely lost its red
color, and has become a pale yellow. It is now ready to be
dyed. An infusion of roasted nutgalls, which have been
boiled for 3-4 hours with water, is applied cold with a soft
brush to the upper hair. Allow to remain so for 2-3 hours,
and without drying, apply a weaker solution of the roasted
nutgalls with a hard brush so as to saturate the hair thor-
oughly. Dry and beat out. According to the concentration
of the solution applied, the hair will be colored blue-grey
137
FUR DRESSING AND FUR DYEING
to black, and the shade can be varied by varying the
strength of the solutions used. The different parts of the
skin, or those parts of different shades can be dyed accord-
ingly."
In this patent all the operations, including killing, mor-
danting and dyeing are done by the brush method, and the
process, from this point of view is quite similar to one
which might have been employed a century previous. It
is evident that the time and effort required to carry out
the details as described in the patent would only be war-
ranted in exceptional cases, where the value of the dyed
fur would be considerably greater than that of the natural
skin.
An example of the application at the same time of dye
and mordant by the brush method is the original French
Seal dye, which is still employed to a limited extent to
produce a brilliant, deep, lustrous black topping on furs
which have already been dyed by the dip process. A typi-
cal formula for the old French Seal dye is the following:
Green copperas 10 parts
Alum 10 "
Verdigris 10 "
Gall-nuts 80 "
Logwood extract
'(15 degrees Twaddell) 150 "
Water 1000
This mixture is applied to the top of the hair of the furs,
after previous killing, and the skins allowed to remain
moist for several hours, and also exposed to the air. The
skins are then dried, and beaten out, and if necessary a
second coat of dye is brushed on. In dyeing seal-imitation
on muskrat, or skunk-imitation on opossum, for example,
the black color required on the top-hair, or the upper part
of the hair when the furs are sheared, can be produced
by applying a mixture similar to the above, to the furs
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VEGETABLE DYES
after they have received their base color by the dip process
with natural dyes or with the Oxidation Colors. Occasion-
ally, the dyeing is given an after-treatment with a dilute
solution of sodium bichromate to help develop the color,
the action in this case being that of an oxidizing agent, and
not of a mordant.
As far as the third method of mordanting is concerned,
that of first applying the dye, and then the mordant, it is
rarely practised with the brush method. The procedure,
however, consists in first brushing on a solution of the de-
sired dye, then drying and brushing on a mordant solution.
These operations are repeated perhaps two or three times
until the proper shade is obtained, exposing the furs to the
air for the color to be developed.
II. DYEING WITH VEGETABLE DYES BY THE
DIP METHOD
It was in the application to furs by the dip process that
the use of the vegetable dyes attained great importance,
and although at the present time, natural organic dyes
have largely been superseded by the Oxidation Colors and
Aniline Black dyes, yet for certain purposes, and especially
for the production of blacks, the wood dyes still are able
to hold their own.
The dyeing of black formerly constituted probably the
most important branch of the fur dyeing industry, and
was undoubtedly the most difficult one. For it is possible
to obtain as many different kinds of black as there are
dyers of this color, but only a few certain shades are desir-
able. The division of the classes of furs into those derived
from the various kinds of sheep, and those obtained from
other animals is particularly marked in the dyeing of black,
and both the composition of the dye formulas and the
methods of dyeing are somewhat different for the two
groups. For the dyeing of black on Persian lambs, broad-
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FUR DRESSING AND FUR DYEING
tails, caraculs, etc., a combination of logwood and nut-
galls with the requisite mordants is used, while on hares,
Chinese sheep, foxes, raccoons, opossum, etc., a mixture
of logwood and turmeric or fustic, with the proper mor-
dants is used.
The general procedure is as follows : The dye substances
to be used are ground up to a powder in a mill constructed
for the purpose, after which they are boiled with water in
a copper-lined kettle or cauldron, heated from the outside
by steam. The customary arrangement is to have a jack-
eted kettle, supported on a stand, and having taps and
valves to enable the liquor to be drawn off, or pivoted, so
that the kettle can be tilted, and the contents poured out.
The use of the copper-lined vessel is to be preferred, as it
is unaffected by any of the dye substances, and so cannot
cause any rust stains. After the dyes have gone into solu-
tion and have cooled, the mordant chemicals, previously
dissolved in water, are added, and the mixture stirred up.
The dyeing in this instance is effected by the simultaneous
application of dye and mordant. The dye mixture is now
run off, or poured out in the proper quantity into a number
of small vats of 25-30 gallon capacity, or into a paddle vat,
which can be closed, while the paddle is rotating. The lat-
ter device is to be preferred because it permits the dye to
retain Its temperature better and for a longer period of
time, but when lambs are being dyed only the open vats
are used. The temperature of the dye mixture is between
40 and 45 C., for only at this temperature can the hair
absorb the dye properly without injuring the leather. The
killed skins are immersed in the dyebath for a time, usually
overnight, after which they are removed, drained and hung
up, with the hair-side exposed to the air, so as to permit
the dye to develop, which takes place with the aid of the
atmopheric oxygen. The dyebath is again brought to the
proper temperature, and the skins are again entered, to go
through the same process as often as is necessary to obtain
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VEGETABLE DYES
the desired depth of shade. The dyed skins are thoroughly
washed to remove excess dye, then dried and finished. The
following are a few dye formulas used in the production of
blacks :
Logwood extract 100 grams
Chestnut extract 14 c.c.
Turmeric 38 grams
Iron acetate 6 Be 50 c.c.
Water 1200 c.c.
or,
Cutch 15 grams
Soda 14 grams
Logwood extract 120 grams
Verdigris 19 grams
Iron acetate 5 Be. 16 c.c.
Water 1200 c.c.
A recently published formula for dyeing China goat skins
black, is the following:
Dissolve 50 Ibs. of dark turmeric and 45 Ibs. of logwood
extract and make up to 300 gallons of solution, at 95 F.
Enter the killed skins and leave them in the liquor until
they rise to the surface. Then take them out and add 25
Ibs. of logwood extract, 10 Ibs. of sumach, 10 Ibs. of blue
vitriol, 5 Ibs. of fustic extract, and about 60 Ibs. of iron
acetate liquor. Stir up well, and immerse the skins for 18
hours. Draw them up, and expose to the air for 12 hours.
Heat the liquor again to 95 F. and put the skins back for
hours. Draw out, hang up in the air for a time, then
wash thoroughly, hydro-extract, dry and finish.
In a German patent, D. R. P. 107,717 (1898), is de-
scribed a method for dyeing lambs black, consisting in
treating the skins for 24 hours in a logwood bath, then
rinsing in cold water, and mordanting for 15 hours in a
solution of bichromate of potash. The skins are then
washed and treated with a solution of iron salt, then dried.
141
FUR DRESSING AND FUR DYEING
This process, while of not much practical importance, is
an illustration of mordanting subsequent to the dyeing
treatment.
As far as the production of other shades is concerned,
the procedure is quite similar to the regular black method.
For a dark brown, for example, the skins are dyed in a
mixture containing
Gall-nuts 40 parts
Verdigris 10
Alum 10 "
Copperas 5
Brazilwood extract
(15 Twaddell) 150 "
Water 1000 "
employing operations just as in the case of the black.
Greyish-blue shades on white hares, lambs, kids, etc., can
be obtained by treating the skins successively in the follow-
lowing baths:
1. Logwood extract 100 grams
Water 1 liter
2. Indigotine 10 grams
Alum 10 grams
Water 1 liter
Bluish-grey tones on the same furs can be produced by
treating with
1. Logwood extract 200 grams
Indigotine 15 grams
Water 1 liter
2. Alum 150 grams
Salammoniac 12 grams
Water 1 liter
142
VEGETABLE DYES
Similar grey shades can be produced by mordanting
the skins with an iron salt, and then dyeing in a weak
bath containing gall-nuts, sumach and iron vitriol. This
method is very effective for making Alaska or silver fox
imitations.
143
CHAPTER XIV
FUR DYEING
ANILINE BLACK
FUR seal for a long time has been a fur of distinction
and importance in the fur industry, and consequently
the dyeing of seal has constituted an important,
though not very extensive branch of the art of fur dyeing.
In quite recent times the popularity of seal has become so
great that imitations have had to be produced to help supply
the demand, and as a result, French seal, or seal-dyed
rabbit, and the so-called Hudson seal, which is seal-dyed
muskrat, have acquired a great vogue. Occasionally opos-
sum, nutria and other furs are also used for the purpose
of producing seal imitations. While the supply of real
seals is relatively small, and the demand large, the pro-
duction of seal imitations has assumed large proportions,
and as a result, the dyeing of seal and its imitations or
substitutes has come to be a great branch of the fur dyeing
industry.
During the past thirty years, the long and tedious proc-
esses of dyeing seal and seal imitations, involving the use
of dyes of vegetable origin, have largely been superseded
by what is known as the Aniline Black dye. It was the
French who first worked out successfully the application
of Aniline Black to furs, and the method has attained much
importance and extensive use in the fur dyeing industry.
Aniline Black is the name given to an insoluble black
dyestuff produced by the oxidation of aniline in an acid
medium. As a finished product it cannot be used in fur
dyeing, but if the hair of the furs be impregnated with a
144
ANILINE BLACK
suitable preparation of aniline and then treated with cer-
tain oxidizing agents, the color will be formed on the hair,
being firmly fixed and giving a fast black, resistant to
light, washing and rubbing. The basis of the dye, aniline,
is an oily liquid, possessing a peculiar fishy odor, colorless
when pure, but rapidly turning brown when exposed to the
air. It is obtained from benzol, which is distilled from
coal-tar, by treating with nitric acid, forming nitrobenzol,
which when subjected to the action of reducing chemicals
is converted into aniline. The process may be shown
schematically as follows:
Coal coal-tar benzol nitrobenzol aniline oil
Aniline Black. Aniline Black was by no means a new dye
when the French succeeded in producing it on furs. It had
been used for a long time previous on textiles, chiefly cotton.
The history of the development of the Aniline Black proc-
ess throws considerable light on its nature and constitu-
tion, and so presents many features of interest. As early
as 1834, the chemist Runge observed the formation of a
dark green color when heated aniline nitrate in the pres-
ence of cupric chloride. Fritsche, in 1840, noticed that
when chromic acid was added to solutions of aniline salt,
a dark green, and sometimes a blue-black precipitate was
produced, and later the same chemist obtained a deep blue
by the action of potassium chlorate on aniline salt. It is
interesting to note that Perkin, in 1856, conducting simi-
lar experiments on the oxidation of aniline with chromic
acid, obtained a blue-black product from which he extracted
the first synthetic coal-tar dye, mauve. Thus far, all the
experiments on the oxidation of aniline proved to be merely
of scientific interest, but in 1862, Lightfoot patented a
process for the practical application of colors formed by
the oxidation of aniline on the fibre, a greenish shade being
obtained by that method, to which the name emeraldine
was given, and by subsequent treatment with bichromate
of potash, the green was changed to a deep blue color.
145
FUR DRESSING AND FUR DYEING
Since that time, the methods for producing and applying
Aniline Black have been developed and improved, although
all the processes were based on the principles incorporated
in Lightfoot's original patent. However, it was not until the
last decade of the nineteenth century that the dyeing of
furs by means of the Aniline Black method was successfully
attempted.
A knowledge of the nature and the manner of the chem-
ical changes which take place in the production of Aniline
Black is a valuable aid in obtaining satisfactory results
in practise; and although Aniline Black was extensively
used before the true character of the reaction was under-
stood, since the successful determination of the constitu-
tion of Aniline Black and the discovery of the real nature
of the process by Green and his collaborators in 1913, the
methods have been considerably improved and simplified,
with correspondingly better results in dyeing. As a conse-
quence, the methods of dyeing furs with Aniline Black have
also become simpler and more efficient.
A discussion of the chemical changes which occur in the
Aniline Black process, is out of place here on account of
the highly involved and complicated character of the reac-
tions, to understand which requires a considerable knowl-
edge of specialized organic chemistry. But the essential
features of practical importance in the production of Ani-
line Black are the following: As already noted, one of
the characteristic properties of aniline is its tendency to
turn from a colorless to a dark-brown liquid in the pres-
ence of the air. This change is due, together with certain
other causes, to an oxidation brought about by atmospheric
oxygen. By employing oxidizing agents, this oxidation
can be accelerated and carried further, and eventually the
Aniline Black is obtained. Among the substances which
may be used to bring about- the conversion of aniline to
the insoluble black dye are manganese dioxide, lead perox-
ide, hydrogen peroxide, chromic acid, ferric salts, potassium
146
ANILINE BLACK
permanganate, chloric acid and chlorates in the presence
of certain metallic salts, particularly those of vanadium and
copper. Chlorates, especially sodium chlorate and potas-
sium chlorate, are the most commonly employed oxidizing
agents, bichromate of soda or of potash being used, in
addition, to complete the oxidation. When using chlorates
it is necessary to have present in the dye mixture a small
quantity of a metallic salt, which, while not entering into
the reaction itself, is nevertheless indispensable as an oxy-
gen carrier. Vanadium compounds have proved to be the
most effective for this purpose, and according to an author-
ity, one part of vanadium salt is sufficient to cause the
conversion of 270,000 parts of aniline to Aniline Black, the
necessary amount of a chlorate being present of course.
Salts of copper, cerium, and iron are also extensively used,
but they are not quite so efficient as vanadium.
The formation of the Aniline Black in practise takes place
in three well-defined steps, which it is important to be
able to recognize and distinguish in order to obtain the best
results. The first stage of the oxidizing process produces
what is called emeraldine, which in the acid medium of the
aniline bath is of a dark green, while in the free state it is
of a blue color. As the oxidation proceeds, the second stage
develops, the emeraldine being converted to a compound
called nigraniline. This in acid solution is blue, and the
free base is a dark-blue, almost black. It was formerly
considered that the nigraniline was the Aniline Black
proper, and so when this stage of the oxidation was reached,
the process was often interrupted and not carried to the
limit. This can account for the fact that Aniline Black
dyeings usually turned green after a short time. The
reason for this is that nigraniline, when treated with weak
reducing agents, as, for example, sulphurous acid, is at once
changed to emeraldine, with -its dark green color. Since
there is usually a small amount of sulphurous acid in the
air, especially in places where coal or gas is burned, an
147
FUR DRESSING AND FUR DYEING
Aniline Black dyeing which has not been carried beyond
the nigraniline stage will be reduced in time to the emerald-
ine, and cause the dyeing to become green. The last step
in the oxidation changes the nigraniline into what is prop-
erly called the ungreenable Aniline Black. Weak reducing
substances like sulphurous acid do not change this com-
pound to emeraldine, and stronger reducing agents only
convert it to a brownish compound, which changes back
to the black when exposed to the air. It is quite evident
that in order to obtain a black which will not change to
green in time, the oxidation of the aniline must be carried
to the last stage. By making tests during the dyeing of
the furs, it can easily be determined whether the oxidation
has proceeded far enough.
In the dyeing of textiles with Aniline Black, it is custom-
ary to carry out the operation at comparatively high tem-
peratures, approaching 100 centigrade. With furs such
temperatures are out of the question, so it is necessary to
repeat the dyeing several times in order to obtain the
proper depth of shade working in the cold. Only the brush
method can be used in applying the Aniline Black dye to
furs, on account of the strong acidity of the dye mix-
ture, which would ruin the leather, if the dyeing were done
in a bath. Indeed, great care must be exercised even by
the brush method to avoid too great penetration of the
dye liquid, otherwise the roots of the hair will be attacked,
and the leather may be " burned " from the hair side. Furs
dyed with Aniline Black are frequently after-dyed by the
dip-process with logwood or some other similar dye, in order
to add to the brilliancy of the dyeing. Combined with in-
tensity of color, Aniline Black on furs is the only dye which
will also give fast, lustrous shades, and leave the hair soft
and smooth.
There are several methods of applying Aniline Black on
furs, the most important being
148
ANILINE BLACK
1. One-bath Aniline Black
2. Oxidation Aniline Black
3. Diphenyl Black
4. Aniline Black by Green's Process
1. One-bath Aniline Black
A typical formula for this method is the following given
by Beltzer:
Aniline salt 10 kg.
Sodium chlorate 1.5 kg.
Copper sulphate 0.7 kg.
Vanadate of ammonia 10 gr.
All these substances are dissolved hot in 50 liters of water,
and allowed to cool, forming solution A. Aniline salt is
aniline oil which has been neutralized with the exact
quantity of hydrochloric acid to form the hydrochloride.
It forms white or greyish crystalline lumps very easily
soluble in water. The sodium chlorate is the oxidizing
agent, and the copper sulphate and the vanadate of am-
monia are the oxygen carriers.
15 kg. of sodium bichromate are also dissolved in 50 liters
of water, forming solution B. The bichromate is also an
ozidizing agent and serves to complete the oxidation of the
aniline to the black.
Immediately before using, solutions A and B are mixed
together, both being cool. In general practise it is cus-
tomary to mix only small quantities at a time, as a con-
siderable precipitate forms when the whole batch is mixed
at once, the precipitate being so much waste dye substance.
Usually a liter of A and a liter of B are mixed at a time,
and the furs brushed with the mixture. The brushing must
be varied according as the hair is hard and stiff, or soft and
tender. The hair must be thoroughly impregnated in all
149
FUR DRESSING AND FUR DYEING
directions, and the penetration must not be too deep to
affect the leather. With experience and dexterity satis-
factory results can easily be achieved. After the skins
have been properly treated, they are dried at a temperature
of about 35 degrees centigrade. When dry, they are' re-
turned to the dye bench, where they receive another appli-
cation of the dye mixture, and are again dried. This opera-
tion may be repeated as often as six or seven times before
a sufficiently intense black is obtained. Another way of
producing the desired depth of shade with fewer applica-
tions is by using more concentrated dye mixtures. Each
method has its disadvantages, the greater number of brush-
ings requiring the expenditure of more time and labor, and
the greater concentration of the bath resulting in a con-
siderable loss of dye substance due to the formation of a
large precipitate when the two solutions are mixed, and
moreover, not all furs can be treated with concentrated
mixtures. The best results with this method usually re-
quire the application of six coats of a mixture of moderate
concentration.
2. Oxidation Aniline Black
In order to overcome the difficulty of employing very
concentrated dye mixtures, or of making many applications
of the dye, a method was devised whereby the two solutions
of the previous process, instead of being mixed together,
are applied successively to the hair of the furs, the following
formula, also by Beltzer, being an example:
Aniline oil 10 liters
Nitric acid 36 Beaume, or
Hydrochloric acid 22 Beaume 20 liters
Cold water 20 liters
This is solution A, and is merely a solution of aniline
hydrochloride, or nitrate, depending on which acid has been
150
ANILINE BLACK
used. Nitric acid, although more costly than the hydro-
chloric acid, is to be preferred, because it is an oxidizing
acid, and so assists in the oxidation of the aniline, and be-
sides, has a more beneficial effect on the hair than the hydro-
chloric, in the matter of softness and luster.
Sodium chlorate 4 kg.
Copper sulphate 1 kg.
Vanadate of ammonia 10 gr.
Water 50 liters
This is solution B, containing the oxidizing agent, and the
oxygen carriers. Just before using, equal quantities of A
and B are mixed, and the skins brushed with the mixture.
The skins are then dried at 35-45 centigrade, at which
temperature the color begins to develop. When almost,
but not entirely dried, the skins are subjected to the action
of warm vapor, which is allowed to enter the drying
chamber, so as to keep the temperature about 40 centi-
grade, the color developing better in this way. This opera-
tion may be repeated, or the skins are directly treated with
a solution of 25 kg. of sodium bichromate in 100 liters of
water, to complete the oxidation. The moist skins are ex-
posed to the air for a time, and then dried at 35 C.
This method of dyeing has several advantages over the
One-bath Aniline Black. It requires fewer brushings, and
enables the complete utilization of the dye solutions with-
out loss. With three applications of the dye mixture by
the Oxidation process, as deep and intense a black can be
obtained as with six brushings by the One-bath method.
The dyeings, too, are nearly, but not fully as brilliant and
even as in the latter case. The greater the number of
coats of dye that are applied the more regular will the
dyeing be.
151
FUR DRESSING AND FUR DYEING
3. Diphenyl Black
In 1902, the Farbwerke Hoechst, a large German producer
of coal tar intermediates and dyes, invented an Aniline
Black process to which they gave the name Diphenyl Black.
The chief departure from the previous Aniline Black
methods was the replacing of part of the aniline oil of the
dye mixture by Diphenyl Black Base I, which is para-
aminodiphenylamine. This base has the property of being
oxidized to Aniline Black, just like aniline oil, and the ad-
vantage claimed for the Diphenyl Black is that it produces
an absolutely ungreenable black. The method of application
is practically the same as for the other Aniline Black proc-
esses, chlorates being used as the oxidizing agents, in the
presence of oxygen carriers such as salts of copper and van-
adium. The use of bichromates is dispensed with. On
account of the comparatively high cost of the Diphenyl
Black Base I, this method has not found very extensive
application, especially as highly satisfactory ungreenable
blacks can now be produced by other methods.
. 4. Aniline Black by Green's Process
In 1907, Green, who has done much work in the direction
of elucidating the character of the Aniline Black process,
obtained a patent f 01$ a method of applying Aniline Black
in a manner which was different from all the previously
known formulas. The invention created great interest,
and although in its original form it did not find a wide
application, many of the methods used at the present time
are in one way or another derived from the idea of Green.
A resume of the patent will therefore be given here: " The
invention relates to the production of an Aniline Black, the
new pr^e^ss differing from all other known processes by the
fact that the oxidation of aniline is effected solely or
mainly by the oxygen of air. The possibility of dispensing
152
ANILINE BLACK
with an oxidizing agent depends on the discovery that the
addition of a small quantity of a para-diamine, or of a para-
amido-phenol to a mixture containing aniline and a suit-
able oxygen carrier, such as a salt of copper, greatly acceler-
ates the oxidation of the aniline by the atmospheric oxygen.
Further, whereas in the ordinary processes of Aniline Black,
the quantity of mineral acid employed cannot be materially
reduced below the proportion of one equivalent to one
equivalent of the base, under the new conditions the
mineral acid may be wholly or partially replaced by an
organic acid such as formic acid, without the quality of the
black being materially affected. As suitable oxygen carriers
the chlorides of copper have been found to give the best
results, it being preferrable to use the copper in the form
of a cuprous salt. This is effected by adding to the dye
mixture cupric chloride, together with a sulphite or bi-
sulphite in sufficient quantity to reduce the cupric salt to
the cuprous state, and a sufficient quantity of a soluble
chloride to keep the cuprous chloride in solution. Among
the compounds suitable for the production of this black in
conjunction with aniline are, para-phenylene-diamine, di-
methyl-para-phenylene-diamine, para-amido-diphenylam-
ine, para-amido-phenol, etc.,"
This method may be used alone as the other Aniline
Blacks, or the dyed skins may be after-dyed in a bath con-
taining a logwood dye, or it may be used in conjunction
with mineral dyes, or with the Oxidation Colors, (see next
chapter). A typical formula for the black by Green's
process is the following:
Para-amido-phenol 0.5 kg.
Aniline oil 10 liters
Hydrochloric acid 22 Be. 10 liters
Acetic acid 40% 5 liters
Cold water 25 liters
153
FUR DRESSING AND FUR DYEING
This is solution A. Solution B is prepared by dissolving
Copper sulphate 2 kg.
Salammoniac 10 kg.
Cold water 50 liters
A and B are mixed, and the mixture applied to the hair of
the furs several times, dryig each time at 35- 40 C. After
three coats of dye have been applied, a pretty and fairly
intense black shade is obtained, which is developed further
by treating with a solution of 25 grams of sodium bichro-
mate per liter of water. The skins are then allowed to
dry in air, and then if desired, an after-dyeing is made with
some other dye.
On account of its extreme fastness, Aniline Black, pro-
duced by any of the methods outlined above, has attained
a justifiable popularity for the dyeing of furs, in spite of the
necessity of using the more or less cumbersome brush
method of applying the dye. Very recently there was issued
to a German company a patent in which is described a
method whereby furs can be dyed with Aniline Black by the
dip process. An abstract of the patent (D. R. P. 33402) is as
follows: " As is known, aniline salt, and similar salts, to-
gether with oxidizing agents like bichromates, chlorates,
etc., cannot be used for dyeing furs by the dip process, be-
cause the strongly dissociated mineral acid is injurious to
the leather. The dissociation of the acid can be reduced
by adding neutral salts, like common salt, or Glauber's salt,
so that good results can be obtained by dyeing in a bath of
the dye mixture, the leather retaining its softness."
Thus far there have been no reports of the successful
practical application of this patent, so its value cannot be
discussed. It is extremely doubtful, however, that furs
will ever be dyed in the dyebath with the present type of
Aniline Black formulas, no matter what substances are
added to prevent the leather from being affected.
154
CHAPTER XV
FUR DYEING
OXIDATION COLORS
THE year 1888 may be considered the beginning of
a new era in the history of fur dyeing; the com-
mencement of a period which was to see the time-
honored, traditional methods of the masters of the art give
way to newer methods of an entirely different character ;
and moreover, the initiation of an age when science with
its basis of fact and logic, was to undertake the rationaliza-
tion of an industry which had hitherto worked upon a more
or less irrational, empirical and uncertain comprehension of
the fundamental principles involved. It was not the work
of a single day, or even of a year which brought about the
virtual revolution in the dyeing of furs, but the result of
long, patient, systematic effort. About this time, the
German coal tar industry was attaining its real stride along
the path of progress and achievement, and had already
succeeded in reaching, to an appreciable degree at any rate,
most users of coloring matters, with the consequence that
the natural dyes, with their time and labor-consuming
processes of application were gradually being superseded by
the new synthetic dyestuffs which could be simply and
quickly applied. It was now the turn of the fur dyeing
industry to receive the attention of the scientists and tech-
nologists responsible for the growth of the coal tar dye in-
dustry, and so there appeared in the above-mentioned year,
the following patents, taken out by a German chemist
named Erdmann:
D. R. P. 47349
A Process for Dyeing Hair and Feathers
155
FUR DRESSING AND FUR DYEING
If white hair or feathers are soaked in an aqueous or
alcoholic solution of para-phenylene-diamine, and then ex-
posed to the slow oxidation of the air, or are treated in a
second solution with some oxidizing agent, then the hair
or feathers will be dyed. According to the oxidizing agent
chosen, and the concentration of the solution used, the color
obtained will be light or dark, varying from the palest blond
to the deepest blue-black. Particularly suitable as oxid-
izing substances are ferric chloride, permanganates, chlo-
rates, hypochlorites, bichromates, and hydrogen peroxide.
The dyeings are fast, that is, they do not come off, and the
color cannot be removed by washing. Following examples
may serve to make the process clear :
20 grams pure para-phenylene-diamine and 14 grams
caustic soda are dissolved in a liter of water. The hair,
previously degreased, is soaked thoroughly in this solu-
tion, and while moist is entered into a three per cent
solution of peroxide of hydrogen. The action is not
instantaneous, but after a day, the hair is dyed a dark
shade; by repetition of these operations a blue-black is
obtained.
The para-phenylene-diamine can be replaced in this proc-
ess by other similar bases, such as dimethyl-para-phenylene-
diamine, as well as the naphthylene-diamines. Since the
substances which can be applied by this process are unin-
jurious, the method described can be used to dye human
hair on the head or beard, and so seems suited to replace
for the dyeing of hair, the metallic salts and various pyro-
gallic solutions which are on the market, and which are
harmful to the health.
D. R. P. 51073 Supplement to 47349; Process
for Dyeing Hair
This patent was an extension of the original patent to
include certain oxy and amido-oxy compounds, the method
156
OXIDATION COLORS
being essentially the same otherwise as in the original
patent. An illustration of the process is as follows:
73 grams para-amido phenol hydrochloride are dissolved
with 40 grams caustic soda in a liter of water. The solu-
tion dyes hair a golden-yellow, which on subsequent treat-
ment with a solution of ferric chloride turns to a red-brown.
In these two patents is to be found the basis of the
modern fur dyes and fur dyeing methods. It is interesting
to note that furs were not mentioned at all in connection
with the process, which was intended mainly for dyeing
hair, especially on the human head. It was only several
years later that the value of the method for dyeing furs
was realized. So about 1894, the Aktien Gesellschaft fiir
Anilinfabrikation put upon the market three fur dyes
under the trade name Ursol, Ursol D, giving dark-brown
to black shades; Ursol P, giving red-brown colors; and
Ursol C, giving a yellowish-brown shade. Pyrogallic acid
had been previously used as a hair dye, and also to a slight
extent as a fur dye, so it was used in conjunction with the
Ursol dyes for shading purposes. The new fur dyes were not
dyes in the ordinarily accepted sense of the term. They
were really coal-tar intermediates, substances similar in
character to aniline, and their dyeing property depended
on the fact that they could be oxidized either by atmos-
pheric oxygen, or by means of oxidizing agents, forming
colored insoluble products. When the oxidation of the
intermediate was caused to take place on the hair the
colored product formed on and in the hair fibre, and re-
mained fast. The reactions bringing about the conversion
of the intermediate to the colored insoluble compound are
quite analogous to those of the Aniline Black process,
though possibly not so complicated, with the important dif-
ference, however, that, while in the production of Aniline
Black acid is essential, in the present instance the oxida-
tion can be carried on in neutral or even alkaline medium.
On account of the character of the method used in applying
157
FUR DRESSING AND FUR DYEING
the new fur dyes, the name Oxidation Colors has been given
to them. Strictly speaking, Aniline Black is also an Oxida-
tion dye, but it is usually considered in a class by itself.
The methods used at first in the application of the Ursol
dyes to furs followed closely the process as described in the
patents. The furs were first killed, usually by brushing
on a lime mixture, drying, and then beating out the dust.
This operation was repeated, if necessary. Then a solu-
tion of the desired dye, mixed with an equal volume of 3%
peroxide of hydrogen was brushed on and the fur allowed
to lie exposed to the air. The dyeing could also be done
by the dip process, less concentrated solutions being used.
By varying the concentration of the solution, and prolong-
ing or shortening the time of action, the shades could be
varied from very light to very dark, and by combining
two or more of the Oxidation Colors, many different color
effects could be produced. Soon other fur dyes were de-
veloped and put on the market; for example, Ursol DB,
giving blue to blue-black shades, and Ursol 2G, yielding
yellowish tones suitable for mixing with the other colors.
Ursol C was discarded shortly after its introduction. The
dyeings obtained with the Oxidation Colors seemed to be
very fast, resisting successfully the action of cold or hot
water, or even hot soap solution. Moreover, a dyed hair
examined under the microscope appeared to be colored
through the epidermis to the medulla, and no individual
particles of dye could be discerned.
The new fur dyes had many evident advantages over the
coloring matters in general use at the time. The simplicity
of the dyeing operations, the short duration of the process,
the great tinctorial power of the new products, were facts
which strongly recommended themselves to the progressive
fur dyer. The cost of the dyes was higher than that of the
vegetable dyes, but this consideration was largely over-
balanced by the saving in time and labor in using them.
And yet, the Ursol dyes found only a comparatively small
158
OXIDATION COLORS
market. The majority of fur dyers, always conservative
and reluctant to turn from the traditional ways of the in-
dustry were skeptical of, and even hostile towards the new
dyes and the new methods of dyeing. In a sense, this oppo-
sition was justifiable. It was not an easy task to relinquish
all at once methods which had been successfully applied for
generations back, and with which they were thoroughly ex-
perienced, in favor of processes which were radically differ-
ent, and with which they had no experience at all. But
some enterprising spirits among the fur dyers undertook to
try out the new products and it was not long before the
skeptics had good cause for condemning the work and
achievements of the chemists as far as fur dyeing was con-
cerned. The new type of dyes did possess some of the
advantages claimed for them, but they also possessed many
highly objectionable features, which had never been mani-
fest with the vegetable dyes. First of all, the dyeings were
not so fast as had at first appeared, for the color came off
the hair when the furs were rubbed, brushed or beaten.
Then it was observed that after a short time some of the
dyeings changed color, and at the same time the hair lost
its gloss and became brittle. The condition of the leather
after dyeing was anything but satisfactory. Most serious
of all, however, was the appearance among the workers in
the dyeing establishments, and also among the furriers who
worked with the dyed skins, of certain pathological condi-
tions which had hitherto been unknown. Various skin
diseases, eczemas, inflammation of the eyes, asthmatic affec-
tions and intestinal irritations were some of the afflictions
which were directly attributable to the use of fur dyes of
the Ursol type. Medical science was at a loss to know how
to treat these ailments, because their nature was not under-
stood.
Here indeed, were obstacles threatening to destroy all the
hopes which the discovery of the new class of dyes had
aroused, and to check at the outset the possibility of rational
159
FUR DRESSING AND FUR DYEING
progress in the fur dyeing industry. But the men of science
were not content to let the matter drop thus. Difficult
problems had been solved before, and surely there must
be some way of overcoming the objections and deleterious
features of a system of fur dyeing which had so much po-
tential merit. Where hindrances sprang up in the path of
progress, it was the duty of the chemist to remove them,
and when difficulties arose, it was up to him to resolve them,
as far as was humanly possible. So the chemists who had
been responsible for the introduction of the Oxidation
Colors set themselves to the task of eliminating the un-
desirable or injurious qualities. It was many years before
the results of painstaking effort and persistent study cleared
up the causes of all the objectionable aspects of the fur
dyes, and suggested means of overcoming them satisfac-
torily. The work had been directed to the improvement
of the dyes and of the methods of dyeing with them. Purer
intermediates were produced, and more easily soluble ones,
so that there would be no possibility of ultra-microscopic
particles of the dye being deposited on the surface of the
hair from the dye solution, instead of being taken up within
the hair fibre. It was this superficial deposition of minute
crystals of the dye or of the only partially oxidized inter-
mediate, on the hair, crystals so fine as to be invisible in
the ordinary high-power microscope, which caused the color
to come off when the furs were brushed or beaten, giving
rise to a dust which was frequently very injurious to the
health. Then, mordants were adopted to help fix the dyes,
compounds of copper, iron, and chromium being used as
formerly with the vegetable dyes, and the range of shades
was also increased thereby. Certain of the Oxidation
Colors had a tendency to sublime off the hair, so the dyed
hair was chemically after-treated in such cases to prevent
this. The causes of the pathological aspects of dyeing with
the Oxidation fur dyes were not so readily disposed of.
But the adoption of devices to prevent the formation and
160
OXIDATION COLORS
circulation of dust during the handling of the dye, the em-
ployment of adequate protection against contact with the
dye or its solutions, the use of the most dilute solutions
possible in dyeing, the thorough washing of the dyed skins
to remove any excess of the coloring matter, the prevention
of dust formation in the drying of the skins, and the rigid
observance of, and adherence to hygienic laws, were all
factors in the elimination of the health-impairing phases
of dyeing with the Oxidation Colors.
It was only after all these improvements had been accom-
plished that the fur dye intermediates began to acquire a
degree of popularity among fur dyers, and strange as it
may seem, there was a more ready market for these dyes
in America, than in Germany where they were manufac-
tured. Other manufacurers of coal-tar intermediates also
began to produce fur dyes, and so, in addition to the Ursols,
there were the Nako brand, the Furrol brand, the Furrein
brand, and one or two others. New dyes were invented,
until the whole range of colors suitable for fur dyeing had
been produced. The black dye, however, presented some
difficulty. A black dye which would rival logwood blacks
could not be attained. Ursol DB in conjunction with
Ursol D was being used to produce bluish-blacks, but the
dyeings were not fast, turning reddish after a time. In
1909, a patent was taken out for a dye mixture, which was
made up like the DB brand, but instead of using toluylene
diamine with para-phenylene-diamine, the new dye was
made up of a methoxy, or ethoxy-diamine with para-phenyl-
ene-diamine, and it yielded brilliant bluish-blacks, which
were fast, and which very nearly approached the logwood
black in luster, intensity, and bloom. For some purposes,
however, the production of a black color is still dependent
on the use of the logwood dye.
When the Great War cut off to a large degree the im-
portation of skins dyed in Europe, the American fur dyeing
industry developed tremendously, and in a comparatively
161
FUR DRESSING AND FUR DYEING
short time was able satisfactorily to accomplish in the way
of dyeing furs, what had taken foreign dyers a much longer
period to attain. It had been previously considered that
furs could be dyed properly only by European fur dyers,
but the achievements in this direction by Americans fully
dispelled this belief. But the success of the fur dyers in
America might not have been so marked or rapid, had it
not been for the work of the American chemists. The war
had also shut off the supply of German dyes, upon which
the dyeing industries of America had formerly been de-.
pendent, so enterprising chemists in this country undertook
to fill the need, and in a surprisingly short time, American
fur dyes, in every respect the equal of the foreign product
were offered to the American fur dyers, and at the present
time, the requirements of the fur dyeing industry in this
country are being adequately met by domestic producers.
Among the brands on the. market are the Rodol, Furamine,
Furol, and several others. The Oxidation Colors are now
being offered in a high state of purity, and easily soluble,
free from any poisonous constituents, and there is abso-
lutely no reason for the appearance of any pathological con-
ditions among workers on dyed furs, or users of such furs,
provided the necessary precautions have been taken in the
dyeing process. The occurrence of any affection which can
be traced to dyed fur, cannot possibly be due to the dye
itself, but to gross carelessness and negligence in dyeing,
and in any such event, the dyer responsible should be
brought to account.
In order to get a better understanding of the nature and
action of the Oxidation Colors, a typical one will be studied
in some detail. The most important one in this class is
para-phenylene-diamine, usually designated by the letter D
in all commercial brands of this fur dye, while its chemical
formula is represented as C 6 H 4 (NH 2 ) 2 . When pure it
occurs in colorless, crystalline lumps, which rapidly
turn brown when exposed to the air; the technical
162
OXIDATION COLORS
product of commerce is of a dark-brown color. It
dissolves readily in hot water when pure, and also in
acids. At one time the hydrochloride was used instead of
the free base, on account of its greater solubility, but now
a base is made which is sufficiently pure to be very soluble
in water. There are several methods of preparing para-
phenylene-diamine : first, by the reduction of amido-azo-
benzol, the product obtained in this way always containing
a slight amount of aniline, which reduces the solubility, and
also gives rise to poisonous oxidation products during the
dyeing process ; second, by the reduction of paranitraniline,
the quality and solubility of the product in this case de-
pending on the purity of the starting material; and third,
by the treatment of para-dichloro-benzol with ammonia
under pressure, the best product being obtained by this
method. The crude para-phenylene-diamine, made by any
of the above processes, is generally distilled in vacuo, the
refined base being obtained as lumps with a crystalline
fracture.
The first step in the oxidation of the para-phe-
nylene-diamine is the formation of quinone di-imine,
NH:C 6 H 4 :NH. This is a very unstable compound in the
free state, and even in aqueous solution it decomposes
within a comparatively short time, or combines with itself
to form a more stable substance. Quinone di-imine has a
very sharp, penetrating odor, and produces violent local
irritations wherever it comes in contact with the mucous
membrane. If a small quantity of para-phenylene-diamine
is absorbed into the human body, by breathing the dust,
or otherwise, the formation of quinone di-imine takes place
internally with consequent irritation of the mucous lining
throughout the body. The various pathological conditions
mentioned before may be ascribed to irritation caused by
quinone di-imine. In any dyeing process where there is a
possibility of the formation of quinone di-imine, as is the
case with most dyes containing para-phenylene-diamine,
163
FUR DRESSING AND FUR DYEING
special precautions must be taken by the workers in hand-
ling the dye or coming in contact with its solutions, and no
one who is particularly sensitive to irritation should be per-
mitted to work in a place where such dyes are used.
The next step in the oxidation of the para-phenylene-
diamine is the formation of what is called Bandrowski's
base. Three parts of the quinone di-imine combine with
themselves, forming a substance of a brown-black color,
which was formerly regarded as the final oxidation product.
The formula of Bandrowski's base is represented by the fol-
lowing chemical hieroglyphics:
(NH 2 ) 2 .C 6 H 3 .N:C 6 H 4 :N.C G H 3 (NH 2 ) 2 .
Further investigation has shown that the oxidation pro-
ceeds beyond this stage with the formation of a compound
of what is known as the azine type, which is depicted by the
chemist as (NH 2 ).C 6 H 3
It is by no means certain that this substance is the true
coloring matter obtained by the oxidation of para-phenyl-
ene-diamine, for the reactions may continue still farther,
producing even more complicated oxidation products.
Scientific research and study has not as yet gone beyond
this stage.
The reactions of the other dyes of the Oxidation type are
quite similar to those of para-phenylene-diamine, some
being simpler, and others being even more complex. The
presence of certain chemical groups in the intermediate,
or the relative position of such groups are factors re-
sponsible for the variations in shade.
With the various mordants, the Oxidation Colors give
different shades, and a great range of colors can be produced
either by combining mordants, or combining dyes, or both.
The following tables illustrate the shades formed with the
customary mordants.
164
OXIDATION COLORS
CHROME
COPPER
IRON
DIRECT
Ursol D
Ursol P
Ursol -2G
Ursol A
brown black
dull red brown
yellow brown
coal black
dull dark brown
dullyellow
brown
coal black
grey brown
yellow brown
blue black
dark brown to
brown black
light brown
dull yellow
blue to blue-
Ursol 4G
Ursol 4R
Ursol
Grey B
light brown
orange brown
creenish crrev
medium brown
light yellow
brown
greenish grey
yellow
red brown
mouse grey
black
pure yellow
orange red
Ursol
Grey R
brownish, grey
brownish grey
reddish grey
Fur dyes of American make being equal in every way to
the German product, show the same color reactions with the
various mordants. The following table shows the shades
produced with the same mordants as above:
CHROME
COPPER
IRON
DIRECT
Rodol D
Rodol P
Rodol 2G
Rodol 4G
Rodol A
brown black
red brown
yellow brown
light brown
coal black
dark brown
yellow brown
light brown
blue black
coal black
grey brown
yellow brown
reddish brown
brownish black
light brown
dull yellow
pure yellow
blue black
Rodol
Grev B
firrep nish crrev
srreenish crrev
mouse grey
Rodof
Grey R
greenish grey
brownish grey
mouse grey
All these shades are produced by dyeing in a bath con-
taining a neutral solution of the dye. Sometimes the dye
comes in the form of a salt of a mineral acid, like hydro-
chloric or sulphuric acid, in which case a sufficient amount
of an alkali, usually ammonia, is added to liberate the free
165
FUR DRESSING AND FUR DYEING
base. According to the Cassella Co., German manufac-
turers of the Furrol brand of fur dyes, the dyeing can also
be carried on in slightly alkaline or in slightly acid solution,
a different series of shades being obtained in each instance.
Ammonia is used to render the bath alkaline, and formic
acid to make it acid. The most customary practise, how-
ever, is to use neutral solutions of the dyes.
For preparing the mordant solutions much smaller
quantities of the metallic compounds are used than in the
case of the vegetable dyes. With chrome mordants cream
of tartar is always employed as an assistant, and occasion-
ally also with copper and with iron mordants. With copper,
and also with iron mordants no addition is made at all, or
sometimes a small quantity of acetic acid is added. The
temperature of the mordant solution is kept about 30 C.,
and the duration of the mordanting varies from 2-24 hours
according to the depth of shade desired. The concentra-
tion of the solution may also be varied, it sometimes being
just as well to use a strong mordant solution and less dura-
tion of mordanting. Chrome may be combined with
copper, and iron may be combined with copper, but chrome
and iron do not go together as mordants. Some typical
average mordanting formulas are as follows :
Chrome mordant.
Bichromate of soda 2.5 gms.
Cream of tartar 1.5 gms.
Water 1 liter
Copper mordant.
Copper sulphate 2 gms.
(Acetic acid 50% 2 gms.)
Water 1 liter
166
OXIDATION COLORS
Iron mordant.
Ferrous sulphate 2 gms.
(Acetic acid 50% 2 gms.)
Water 1 liter
or,
Iron pyrolignite 30% 10 gms.
Water 1 liter
Chrome-copper mordant.
Bichromate of soda 2 gms.
Copper sulphate 0.25 gms.
Cream of tartar 1.0 gms.
Water 1 liter
Copper-iron mordant.
Copper sulphate 2 gms.
Ferrous sulphate 2 gms.
(Acetic acid 50% 2 gms.)
Water 1 liter
The killed skins are immersed in the mordanting solution,
and allowed to remain the required length of time. They
are then thoroughly rinsed to remove any excess of the
mordant, and are hydro-extracted. Under no circumstances
should mordanted skins be permitted to dry, for they would
be unfit for use again.
The dyebath is next prepared by dissolving the necessary
quantity of the dye, varying from 0.1 gm. to 10 gms. per
liter. Then if the solution must be neutralized, the am-
monia is added and the temperature of the bath is brought
to 30-35 C. by the addition of cold water. This tempera-
ture is maintained throughout the dyeing operation. To the
solution is added the oxidizing agent. Ordinary commercial
167
FUR DRESSING AND FUR DYEING
peroxide of hydrogen containing 3% by weight is the usual
oxidizer, although perborates have been suggested. 15-20
parts of peroxide of hydrogen for every part of dye are
added, and the dye solution brought to the proper dilution.
As soon as the dyebath is ready, the skins are entered, and
worked for a short time to effect even penetration. They are
then left in the dyebath for 2-12 hours or longer according
to the depth of shade. After being satisfactorily dyed, the
furs are rinsed thoroughly, hydro-extracted and dried and
finished. Where the dye is to be applied by the brush
to the tips of the hair, stronger dye solutions are used,
the brushed skins being placed hair together and let lie for
about 6 hours in order to permit the color to develop, after
which the furs are dried and drum-cleaned.
Some shades, particularly black, have a tendency to rub
off slightly. In order to overcome this, the dyed furs, after
rinsing, are treated with a cold solution of part of
copper sulphate per 1000 parts of water, for 3-4 hours, then
without rinsing, hydro-extracted and dried. Furs which have
been tipped are brushed with a 1-2% solution of copper
sulphate and dried. Care must be taken in this after-treat-
ment, for the use of too strong a solution of copper sulphate,
or too prolonged action of such a solution will materially
alter the shade of the dyed fur.
A few typical formulas will serve to illustrate the general
methods of employing the Oxidation Colors:
Brown Sable Imitation on Unsheared Rabbit
The skins are killed with soda, soured, and washed, then
mordanted with
Bichromate of soda 2 grams
Copper sulphate .25 grams
Cream of tartar 1 gram
Water 1 liter
168
OXIDATION COLORS
for 24 hours. Then washed, and dyed for 24 hours with
Fur Brown 2G 1 3 grams
Hydrogen peroxide 45 grams
Water 1 liter
Wash and dry the skins, then brush the tips with
Fur Brown D x 20 grams
Hydrogen peroxide 400 grams
Water 1 liter
Black on Sheared Muskrat
The skins are killed with soda, soured, and washed, then
chrome mordanted for 6 hours. Then they are dyed for
6 hours with
Rodol P 1.5 grams
Pyrogallic acid .7 grams
Ammonia 2.0 grams
Hydrogen peroxide 45 grams
Water 1 liter
The dyed skins are washed and dried, then tipped with
Rodol D 20 grams
Rodol DB 2 grams
Hydrogen peroxide 450 grams
Water 1 liter
Brown on Thibet Sheep Skin
The killed skins are mordanted for 6 hours with a chrome
mordant, then dyed for 6 hours with
Ursol P 1 gram
Pyrogallic acid 1 gram
Ammonia 2 grams
Hydrogen peroxide 40 grams
Water 1 liter
1 Inasmuch as most manufacturers use the same letters to designate the
various dyes, any equivalent brand of fur dye may be used in place of those
here mentioned.
169
FUR DRESSING AND FUR DYEING
It is also possible to combine dyeings with the Oxidation
Colors with Vegetable dyeings, or with Aniline Black. For
example, if it be desired to produce an imitation skunk
on a raccoon, and an exceptionally fast and intense and
lustrous black on the tips of the hair, the skins are dyed in
the bath with the Oxidation dyes, and the tips of the hair
are brushed with a mixture such as described under Vege-
table Colors for the production of French seal, as follows :
Imitation Skunk on Racoon
The skins are killed with caustic soda, soured and washed,
then mordanted with an iron-copper mordant as described,
and then dyed with
Fur Grey R 3 grams
Ammonia 2 grams
Peroxide of hydrogen 45 grams
Water 1 liter
After washing and drying, the dyed skins are brushed over
with a mixture such as used for dyeing French seal with
Vegetable Colors.
In a similar manner, the Oxidation Colors may be used
to give a base color to furs dyed by the Aniline Black
process.
It is apparent from these few illustrations that a great
variety of shades can be produced, and the dyeing of imita-
tions of the better class of furs on cheaper skins is a com-
paratively simple matter, after an understanding of the
nature of the dyes has been obtained, and a certain amount
of skill acquired in working with these dyes.
170
CHAPTER XVI
FUR DYEING
COAL TAR DYES
IN addition to the Aniline Blacks and the Oxidation
Colors already discussed there are certain of the syn-
thetic coal tar dyes such as are generally used in the
dyeing of textiles, which can also be applied on furs. There
are several classes of these dyes, varying somewhat in their
nature, and consequently in their manner of application;
in the main they produce bright shades, such as are but
seldom used on furs, yet which may occasionally serve for
the production of novel effects. Basic, acid and chrome
colors are the types which can be employed.
Basic .colors possess great fullness and tinctorial strength,
but have a tendency to rub off, and the tips of the hair
take a darker shade with these dyes than the rest of the
hair. The addition of acetic acid and Glauber's salt to the
dyebath will result in a more uniform dyeing. On account
of the comparatively poor fastness to rubbing and washing,
basic dyes are used only for dyeing furs which are intended
for cheap carpet rugs, such as sheep and goat. They may
also find use in the production of light fancy shades on
other white furs. The procedure is usually as follows: The
furs are killed in the customary manner with soap and soda
or ammonia, or if this is insufficient, with milk of lime. A
soap-bath is then prepared containing 2.5-6 grams of olive-
oil soap per liter of water. The temperature of the bath is
brought to 40 C. To this is added the solution of the dye-
stuffs, prepared by mixing the required color or colors with
a little acetic acid to a paste, and then pouring boiling water
171
FUR DRESSING AND FUR DYEING
on the mixture until dissolved. Undissolved particles or
foreign matter are removed by passing this solution through
a cotton cloth or sieve, and the clear solution then mixed
with the soap-bath. The well-washed skins are then
entered into the dyebath and immersed for about half an
hour, or until the desired depth of shade is obtained. They
are then removed, pressed or hydro-extracted and dried.
For the production of light shades, the following dyes may
be used:
For cream, light sulphur-yellow, maize, salmon, etc.
Combinations of
Thioflavine
Rhodamine B
Irisamine G
For greenish-yellows
Combinations of
Thioflavine
Victoria Blue B
For light pink
Rhodamine B
Irisamine
Rose Bengal Extra N
For purple
Methyl Violet 3B-6B
Crystal Violet
For sky-blue
Victoria Blue B
For white
Victoria Blue B (Milk-white)
Methyl Violet 3B-6B
Crystal Violet (Ivory-white)
172
COAL TAR DYES
To produce very delicate shades, the moist dyed skins are
subjected to a sulphur bleach overnight, to lighten the color,
then rinsed, and dried. Full, brilliant shades may be ob-
tained by dyeing in a bath of 40 C., acidulated with 2-3
grams of acetic acid per liter of solution, the following dye-
stuffs being suitable:
For yellow to orange
Thioflavine
Paraphosphine
Rhodamine
Safranine
New Magenta O
For pink
Rhodamine B
Rose Bengal Extra N
For light red
Safranines
For bordeaux and red
Magenta
New Magenta
Russian Red
Cerise
For violet
Methyl Violet 6B-4R
Crystal Violet 5B
For blue
Victoria Blue B
Methylene Blue BB
New Methylene Blue N
173
FUR DRESSING AND FUR DYEING
For green
Malachite Green Crystals
Brilliant Green Crystals, or combinations of
Thioflavine
Diamond Phosphine
Victoria Blue B
For brown
Chrysoidines
Bismarck Browns
In dyeing skins with harder hair than that of sheep or goat,
mere killing is insufficient to render the hair capable of
taking up the dye. The skins are therefore immersed before
dyeing, in a cold, weak solution of chloride of lime, the
affinity of the hair for the dye being thereby greatly in-
creased.
Acid dyes are employed when a greater fastness is re-
quired than can be obtained with the basic colors. Sul-
phuric acid in a quantity equal to half the weight of the
dyestuffs used, together with four times that quantity of
Glauber's salt is added to the dyebath. Formic acid may
be used in place of the sulphuric acid, very good results
being obtained. The skins are immersed in the dyebath,
and worked until thoroughly soaked with the dye liquor,
and then allowed to remain until the proper depth of shade
is attained, or overnight. The temperature of the solution
is about 40 C., and only very light shades can be produced
in this manner. In 1900 and again in 1914, the Cassella Co.,
a large German manufacturer of dyestuffs, obtained patents
for processes enabling the dyeing of furs in hot solution
with the acid dyes. The method required that the skins
be chrome-tanned in order to render them resistant to the
action of hot solutions, the addition of a small amount of
formaldehyde to the chrome solution increasing this effect.
The skins are then treated with a solution of chloride of
174
COAL TAR DYES
lime in order to increase the affinity of the hair for the dye-
stuffs. The method as it is now practised is as follows:
The skins which have been cleaned and washed are chrome
tanned by the method as described in the chapter on Tan-
ning Methods, 60 grams of formaldehyde being added to
every 10 liters of the chrome solution. After proper tanning
the skins are rinsed, and while still moist they are subjected
to a treatment with chloride of lime. They are first im-
mersed for 15 minutes in a cold bath containing 120 grams
of hydrochloric acid 32-36 Twaddell per 10 liters of water,
then without rinsing, they are entered into a bath made up
by adding gradually in four portions the clear solution of
2-4 grams of the chloride of lime per 10 liters of water.
After working for an hour, the skins are removed and
entered again into the acid solution, in which they are
worked for another 15 minutes. In order to neutralize and
remove the last traces of the chloride of lime from the
furs, they are rinsed in a luke-warm bath containing 1-2
grams of sodium thiosulphate, or hyposulphite of soda, in
10 liters of water. The skins are then rinsed again, and
hydro-extracted, or pressed, and are ready for dyeing. The
dyebath is prepared with the required quantity of dye, to
which is added 10-20% Glauber's salt and 2-5% acetic
acid (both calculated on the weight of the skins). The
skins are entered at 20 C., then after three-quarters of an
hour to 40 C., and then after another hour slowly to
50-55 C. For blacks, the temperature is raised as high
as 65 C. After dyeing the skins are treated with a solution
containing per 10- liters
90-120 grams of olive-oil soap
12-25 grams olive oil
12 grams ammonia
for 15 minutes, then hydro-extracted and dried, without
further rinsing.
175
FUR DRESSING AND FUR DYEING
For this method of dyeing, the following dyes may
be used :
For yellow and orange
Fast Yellow S
Acid Yellows
Naphthol Yellow S
Tropaeoline
Orange GG, R, II, IV
For blue
Cyanole FF
Azo Wool Blue
Naphthol Blue R
Formyl Blue B
For brown, combinations of
Fast Yellow S
Acid Yellows
Tropaeoline DD
Orange GG
Lanafuchsine
Indigo Blue N
Cyanole B
Fast Acid Green BN
For reds
Acid Reds
Lanafuchsine
Azo Orseille
For violet
Azo Wool Violet
Acid Violets
For green
Naphthol Green B
Fast Acid Green
Cyanole Green
For black
Naphthylamine Blacks
Naphthol Blacks
Naphthol Blue-black
For grey
Silver Grey N
Dyed with the addition of
-l of alum
The chrome colors are dyed on furs when very fast
shades are desired, all the fancy colors being produced in
this manner, but for black, only the acid dyes are suitable.
The preparation of the skin is exactly the same as for the
acid colors, except that the treatment with chloride of lime
may be omitted, although for very full shades it is desirable.
The dyeing is carried out as follows: The dyebath is pre-
pared with the requisite amount of the desired dyestuff,
which is previously dissolved, and to this is added a solu-
tion of sodium bichromate, the amount of this substance
being half the weight of the dye. The solution is heated
176
COAL TAR DYES
and the skins entered and dyed for 1-2 hours at 70-80 C.
Then the dyebath is exhausted by the addition of \%
acetic acid, the skins being worked for another half hour,
then rinsed, hydro-extracted and dried. Any of the one-
bath chrome, or after-chrome colors may be used for this
method.
Recently methods have been patented for the dyeing of
furs by means of the vat colors. Vat dyes are among the
fastest coloring matters ever produced, and their appli-
cation on furs would be a great advantage, if suitable shades
could be obtained. The general process for dyeing with
vat colors, consists in reducing the dye, which is usually
very insoluble, into a soluble " leuco " compound, by means
of hydrosulphites in the presence of alkalies. The leuco
compound is not a dye itself, but when the fibre absorbs it,
and is then exposed to the air, the leuco compound is re-
oxidized to its original insoluble form, which remains fast
and permanent. The use of strong alkalies in vat dyeing
has hitherto been a great obstacle in the use of these dye-
stuffs, but in 1917, the Farbwerke Hoechst, a large German
dyeworks, patented a process as follows : " A process for
dyeing furs with vat colors. The dyeing is done in solu-
tions of the vat dyes (after the addition of gelatine or some
other protective colloid), which are rendered neutral or
only slightly alkaline with ammonia, by neutralizing the
caustic soda of the solution of the leuco compound of the
vat dyes by the addition of ammonium salts, or suitable
acids. The dyeings thus obtained are uniform and fast,
the leather is dyed to only a slight degree, and shows no
deleterious effects of the dyebath on the tannage." As a
practical application of this process, another patent was
taken out by the same company, also in 1917, as follows:
" A process for producing fast blacks on furs, consisting of
dyeing a ground color with appropriate vat dyes in a hydro-
sulphite vat, and after oxidation in air, topping with an
Aniline or Diphenyl black. The dyeings obtained by the
177
FUR DRESSING AND FUR DYEING
combination of vat dyes which are fast to oxidizing agents,
with an oxidation black, have an appearance matching that
of logwood black in beauty; and with a dark-blue to blue-
black under-color, and a full, deep black top color, can-
not be distinguished from logwood. These dyeings also
have the advantage of being faster to light than logwood or
other blacks."
While these processes undoubtedly have many meritorious
qualities which make them interesting, they do not seem as
yet, to have attained any great practical application.
However, it is a field of fur dyeing which is worth while
developing, and with certain necessary improvements in
these processes, the vat dyes may yet supersede partially
some of the other methods of dyeing furs.
178
CHAPTER XVII
BLEACHING OF FURS
BLEACHING is for the purpose of lightening the
color of furs, and is most generally applied to white-
haired skins such as white fox, ermine, and
occasionally white lambs of all kinds, and white bears.
Among such furs, pelts of a naturally pure white tone are
relatively scarce, while in the majority of cases the color
ranges from a pale creamy white to a decidedly yellowish
shade.) Colors which vary from the pure white detract con-
siderably from the attractiveness and consequent value of
the fur, and indeed, some pelts are so far off shade that
they can only be used when dyed a darker color. Most
white skins which are but slightly inferior in color can be
brought to a pure white by bleaching, and they can then
be used natural. Some pelts, on the other hand, are par-
ticularly resistant to the action of bleaching agents and
cannot be sufficiently decolorized to render them suitable
for use natural, so these are also dyed. For the production
of certain delicate or fancy dyed shades on white furs, it is
often necessary to bleach the skins in order to be able to
obtain pure tones. Such instances are not very common,
however. Occasionally dark furs, such as beaver, are
bleached on the tips of the hair, a golden shade being
obtained thereby, which at one time was quite popular, but
recently such effects have not been in vogue.
In the bleaching of furs, two steps may be distinguished,
first degreasing, and second, bleaching proper. In the pre-
liminary operations of fur dressing, the furs are treated with
soap or weak alkalies to cleanse them and to remove excess
oil from the hair. During the various processes and ma-
179
FUR DRESSING AND FUR DYEING
nipulations, the hair, especially on white skins, may be-
come soiled or somewhat greasy again, so it is advisable to
repeat the cleaning process. / This should in every case be
as light as possible, using aWeak solution of soap for the
softer and cleaner pelts, or dilute solutions of ammonium
carbonate or soda ash for the more greasy-haired skins.
The skins are then thoroughly rinsed to remove all traces
of the degreasing material. This step is very essential in
order to obtain uniform bleaching.
Broadly speaking, there are two general methods which
can be used in bleaching furs, one involving the use of what
are known as reducing agents, and the other employing
oxidizing substances.
Among reducing agents which can be used for bleaching
furs are sulphurous acid, and its salts such as sodium bisul-
phite and sodium sulphite; hydrosulphites, and derivatives.
1. Sulphurous acid. When sulphur is burned, sulphur
dioxide gas is formed. In the presence of moisture, or when
dissolved in water, this gas forms sulphurous acid, which is
one of the most commonly used bleaching chemicals for all
sorts of materials, and is very effective for decolorizing furs.
The procedure usually followed is to hang up the moistened
skins on wooden rods in a more or less cubical chamber
made of stone or brick, and lined with wood or lead. No
other metals may be used, because they are quickly cor-
roded by the sulphurous acid. The requisite quantity of
sulphur is placed in a pot in the bleaching chamber, and
then ignited, after which the doors are shut tight. The
fumes of the burning sulphur in contact with the moist hair
readily exert their bleaching action on the furs, and the
operation is allowed to proceed for six or eight hours, or
overnight. Then by means of fans or other devices, the air
filled with sulphur dioxide gas is withdrawn from the
chamber, and replaced by fresh air. The door is opened,
the skins removed, exposed to the air for a time, then
rinsed, and finally dried and finished. Sometimes one
180
BLEACHING OF FURS
operation is not enough N to sufficiently bleach the hair, so
the process is repeated. Sulphur dioxide gas can now be
obtained compressed in cylinders, which are more conven-
ient to handle than burning sulphur. The flow of gas which
is introduced into the bleaching chamber by means of a
nozzle attached to the cylinder, can be regulated, and the
bleaching thus retarded or accelerated.
2. Sodium bisulphite and sodium sulphite. These salts
of sulphurous acid are effective in their bleaching action
only when in solution in the presence of acids. The acids
liberate sulphurous acid from the salts, so this method is
virtually the same as 1. Instead of using the salts of sul-
phurous acid, sulphur dioxide may be dissolved in water,
and the solution used for bleaching by immersing the furs
in it. This procedure, while consuming somewhat less time
than the chamber process, is more likely to affect the
leather, which would have to be retanned. The principle
is the same as that involved in method 1.
3. Hydrosulphites and derivatives. The bleaching
agent can be prepared by adding zinc dust to commercial
bisulphite of soda dissolved in about four times its weight
of water until no more reaction is evident. Milk of lime is
then added to precipitate the zinc, and the clear superna-
tant liquid of 1.5-5 Tw. is used for bleaching. The skins
are immersed for 12-24 hours, taken out, washed and
finished. Instead of preparing the hydrosulphite, the com-
mercial products may be used with greater convenience, a
solution containing 1-4% of the hydrosulphite powder be-
ing used, and the skins treated in this until satisfactorily
bleached.
The bleaching action of sulphurous acid and hydrosul-
phite is supposed to be due to the reduction of the coloring
matter of the hair to a colorless compound; or possibly to
the formation of a colorless compound of the bleaching
material with the pigment. The former seems the more
probable explanation, because the change is not a perma-
181
FUR DRESSING AND FUR DYEING
nent one, the original natural color returning after a long
exposure of the bleached fur to air and light. However,
the results are sufficiently enduring to satisfy the require-
ments of the trade in the class of furs on which these meth-
ods of bleaching are used.
Bleaching chemicals with an oxidizing action generally
used for decolorizing furs are hydrogen peroxide and per-
oxides; occasionally hypochlorites and permanganates are
also used.
1. Hydrogen peroxide. Hydrogen peroxide is usually
employed for bleaching in the form of its 3% solution, to
which is added about 20 cubic centimeters of ammonia
per liter. The ammonia serves partially to neutralize the
acid which commercial peroxide generally contains, and also
to facilitate the bleaching action. The thoroughly de-
greased skins are immersed in the solution until the hair is
completely wetted by it, are then removed, and evenly
pressed or hydro-extracted, after which the pelts are hung
up to dry in the air. As the hair becomes drier, the con-
centration of the peroxide becomes greater, and conse-
quently the bleaching action is stronger. Where there is
a likelihood of the leather being affected by the bleaching
solution, the ammoniacal peroxide may be applied to the
hair with a fine sponge or brush until sufficiently wetted,
and then hanging the skins up to dry. Repetition of the
process is sometimes necessary to obtain pure white, but the
results are always excellent.
2. Peroxides. The most important of these is sodium
peroxide, which comes on the market as a yellowish-white
powder, which must be kept dry, and away from any in-
flammable material, as fires have been caused by the con-
tact of the peroxide with such substances. When dissolved
in water, it is equivalent to a strongly alkaline solution of
peroxide of hydrogen.
182
BLEACHING OF FURS
Na 2 2 4
2 H 2 O
= H 2 2 4
2 NaOH
sodium
water
peroxide
caustic
peroxide
of
soda
hydrogen
When dissolved in acid, the alkali is neutralized, and a
neutral solution of peroxide of hydrogen and a salt is ob-
tained, and this method is used to obtain peroxide of
Na 2 O 2 + H 2 SO 4 = H 2 O 2 + Na 2 SO 4
sulfuric sodium sulphate
acid
hydrogen cheaply. 3 parts of sodium peroxide are slowly
dissolved in a cold 1 % solution of 4 parts of sulphuric acid,
stirring during the addition, and making the resulting solu-
tion neutral to litmus paper, acid or more sodium peroxide
being added as needed. There is then added 3-6 parts of a
solution of silicate of soda of 90 Tw. The skins are im-
mersed until properly bleached, taken out, passed through
a weak acid solution, then washed and finished. This
method generally requires the leather to be retanned after
bleaching. Another process, which involves the use of
peroxides, but which is not commonly practised, consists in
rubbing the hair with a pasty mixture of equal parts of
water, barium dioxide, and silicate of soda, hanging up the
skins to dry, and then beating and brushing the hair.
3. Permanganates. The only member of this group
that finds practical application for bleaching purposes is
potassium permanganate. The skins are immersed in
a 0.1% solution of the crystals of potassium permanganate,
until the hair acquires a deep brown color. They are then
removed, rinsed, and entered into a second bath containing
sulphurous acid in solution, prepared by acidifying a solu-
tion of sodium bisulphite. The skins are then worked in
this until fully bleached. It is the permanganate which
does the bleaching, the sulphurous acid being for the pur-
183
FUR DRESSING AND FUR DYEING
pose of dissolving the brown compound of manganese
formed on the hair.
4. Hypochlorites. Chloride of lime and sodium hypo-
chlorite, which is prepared from the former, are the chief
chemicals of this type used for bleaching. The skins are
entered into a weak solution of the hypochlorite, and left
until the hair is decolorized; then after removing, they are
passed through a dilute acid, and subsequently through a
weak solution of sodium thiosulphate in order to remove all
traces of the hypochlorite. This method causes the hair to
acquire a harsh feel, and the yellow color is never entirely
eliminated. The hair, however, possesses a great affinity
for certain types of dyestuffs, and it is only when these
particular classes of dyes are to be applied to the furs, that
the hypochlorite bleach is used. (See dyeing with Acid
colors) .
The various oxidation methods of bleaching are supposed
to change the coloring matter of the hair into an entirely
different and colorless compound which cannot return to its
original form. The bleach is therefore permanent.
In common practise, the sulphurous acid, and the perox-
ide of hydrogen methods are the two chiefly employed in
bleaching processes. Sulphurous acid is used to bleach the
cheaper kinds of furs, while peroxide of hydrogen is applied
to the finer furs.
Whichever process is used, it is customary to give the
bleached skins a subsequent " blueing," by passing them
through a very weak solution of a blue or violet dye, such
as indigo-carmine, crystal violet, alkali blue or ultramarine.
The furs are then dried and finished off as usual. In drum
cleaning white furs, gypsum or white sand, or sometimes
even talc are used with the sawdust, or occasionally alone
without the sawdust.
184
BIBLIOGRAPHY
Allen " Commercial Organic Analysis "
Armour, B. R. " Fur Dressing and Dyeing " 1919
- Color Trade Journal, Vol. 1, p. 51-53
- Jour. Amer. Leather Chemists' Assn., Vol. 13, p. 63-69.
Belden, A. L. " Fur Trade in America " 1917
Beltzer, F. J. G. " Industrie des Foils et Fourrures, etc." 1912
Revue Generale des Matieres Colorantes, Vol. 12, 1908
Bennett, H. G. " Manufacture of Leather " 1910
Bertram, P. Deutsche Farber-Zeitung 1895-96 Heft 17, p. 266
Bird, F. J. " American Practical Dyers' Companion " p. 241-245
Boerner, H. Kunststoffe, 1912 p. 223
Brevoort, H. L. " Fur Fibres as shown in the Microscope " 1886
Bucher, B. " Geschichte der technischen Kunste " 1875-1893
Cubaeus, P. " Das Ganze der Kiirschnerei " 1912
Davis, C. T. " Manufacture of Leather "
Erdmann, E. Deutsche Farber-Zeitung 1894-95 Heft 21, p. 337
Zeitschrift fur angewandte Chemie, 1895, Heft 14
Zeitschrift fur angewandte Chemie, Heft 35, 1905
- Berichte, 1904, 37, p. 2776, 2906
Farrell, F. J. "Dyeing and Cleaning" 1912
Fougerat, L. " La Pelleterie dans 1'antiquite, la prehistoire, etc."
Fleming, L. "Practical Tanning" 1916
Gardner, W. M. "Wool Dyeing" 1896
Grandmougin, E. Zeitschrift fiir Farben-Industrie, 1906, 5, p. 141
Gruene, E. Deutsche Farber-Zeitung, 1895-96 Heft 13, p. 197
Halle " Werkstatte der heutigen Kunste," 1762, Vol. 2, p. 317
Hartwig, O. L. " Sprengler's Kunste und Handwerke," 1782
Hausman, L. A. Scientific Monthly, Jan. 1920; March, 1921
- Natural History, Vol. 20, 4, 1920
- American Journal of Anatomy, Sept. 1920
American Naturalist, Nov.-Dec. 1920
Hayes, A. H. National Cleaner and Dyer, Nov. 1920, p. 55-57
Jacobson, " Schauplatz der Zeugmanufacturen " p. 493
Jones, J. W. " Fur Farming in Canada " 1913
Knecht, Rawson & Loewenthal " Manual of Dyeing " 1916
Kobert, R. " Beitrage zur Geschichte des Gerben und der Astringentien "
1917
Koenig, F. Zeitschrift fiir angewandte Chemie, 1914, Vol. 1, p. 529
Lamb, M. C. " Dressing of Leather " 1908
185
BIBLIOGRAPHY
Jour. Soc. Dyers & Colourists 1913, 29, p. 160-165
Lamb, J. W. Jour. Soc. Dyers & Colourists Dec. 1905, p. 323
Larish & Schmid " Das Kuerschner Handwerk " 1-3
Laut, A. C. " The Fur Trade of America " 1921
Martin, G. " Industrial Organic Chemistry "
Lightfoot, J. " The Chemical History & Progress of Aniline Black " 1871
Mairet, E. M. "A Book on Vegetable Dyes" 1916
Matthews, J. M. " Application of Dyestuffs " 1920
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Mierzinski, S. " Die Gerb und Farbstoffextrakte "
Noelting & Lehne " Anilin-Schwarz " 1904
Perkins & Everest " Natural Organic Coloring Matters " 1918
Petersen, M. "The Fur Traders & Fur-Bearing Animals" 1920
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" Tanning "
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Deutscher Fiirber-Kalender 1911, p. 65
- Leipziger Farber-Zeitung 1909, p. 441
Schmidt, C. H. " Handbuch der Weissgerberei "
Setlik, B. Deutsche Farber-Zeitung 1901, p. 213
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Textile Recorder, Vol. 36, p. 292-293, Dec. 1918
- Revue Generale des Matieres Colorantes, Vol. 23, p. 32-36
Stevenson, C. H. " U. S. Fish Commission Report 1902-1903, Bulletin
No. 537
Stickelberger, E. " Geschichte der Gerberei " 1915
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Werner, H. "Die Kiirschnerkunst " 1914
- " Das Farben der Rauchwaren " 1914
Whittaker, C. M. " Dyeing with Coal Tar Dyes " 1919
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Witt-Lehman " Chemische Technologic der Gespinst-Fasern " 1910
Zeidler, H. "Die moderne Lederfabrikation " 1914
186
INDEX
Acetate, aluminum, 118
chromium, 120
- copper, 120
ferrous, 119
lead, 126
Acetic acid, 112
Acid dyes, 174
Acids, action of, on hair, 29
on skin, 26
After-treatment with copper, 168
Alaska fox imitations, 143
Alkaline aluminum mordants, 122
chromium mordants, 123
iron mordants, 123
Alum, 32, 53, 118
chrome, 57
chrome tans, 64
tans, 54, 56
Aluminum acetate, 118
mordants, 118
sulphate, 53, 118
Ammonia, 110
Ammonium sulphide, 126
Aniline black, 144
by dip process, 154
- chemistry, 145
- Green's process for, 152
- nature of, 144
One-bath, 149
Oxidation, 150
- processes, 149
ungreenable, 148
Aniline oil, 145
Astrachan 5, 7, 12
Bacteria, 51
Badger, 7
Ball-drum, 62
Bandrowski's base, 164
Basic dyes, 171
Beam, 38
Beaming, 38
Bear, black, 5, 7
brown, 5, 8
white, 8
bleaching of, 179
Beating furs, 79
Beaver, 5, 8, 25, 83, 94
Beechwood ashes, 108
Bichromate of soda, 121, 147
Black, aniline, 144
by Green's process, 152
chemistry of, 145
nature of, 144
One-bath, 149
Oxidation, 150
ungreenable, 148
Black, diphenyl, 152
logwood, 139
on Chinese goats, 141
on lambs, 141
on raccoon, 130
on skunk, 130
on wolf, 130
Bleaching of furs, 179
Blending, 91, 104
Blue-grey on white furs, 142
Blueing, 184
Blue salt, 120
vitriol, 119
Borax, 39, 58
Brasilein, 135
Brasilin, 135
Brazilwood, 135
Bright shades on furs, 171
Broadtail, 8, 12
dyeing of, 139
Brown on Thibet sheep, 169
with natural dyes, 142
Brush process, 98
Brushes used in dyeing, 100
Butter, 60, 63
Cage, 80
Cageing, 80
Campeachy wood, 133
Caracul, 8, 12
dressing of, 53
187
INDEX
Caracul, dyeing of, 140
Carnivorous animals, furs of, 37
Cased skins, 36
Castor oil, 60, 63
Cat, civet, 5, 8
- house, 8
Caustic soda, 44, 110, 113
Centrifugal machine, 40
Chamber drying, 73
Chamois dressing, 31
- tan, 49, 58, 61
Characteristics of tans, 65
Chestnut extract, 133
Chinchilla, 5, 6, 8, 94
- blending of, 91, 104
Chinchillone, 9
China goat, black on, 141
Chlorates, 147
Chloride of lime, 174
- bleach, 184
Chrome acetate, 120
- alum, 57, 120
- colors, 176
-copper mordant, 167
-formaldehyde tan, 64
- tans, 57, 174
Chromium mordants, 120, 166
- alkaline, 123
salts in tanning, 53
Cleaning pelts, 40
Coal tar colors, 171
Cocoanut oil, 60
Cod-liver oil, 60
Collagen, 25
Colloidal solutions, 48
Combination tans, 49, 64
Conveying dyed skins, 104
Conveyor drying, 73
Copper acetate, 119
- mordants, 119, 166
- salts, 109
- after-treatment with, 168
- sulphate, 119
Copperas, 119
Copper-iron mordant, 167
Coriin, 21
Corium, 21
Cortex, 23
Cottonseed oil, 60, 63
Cuba wood, 134
Cutch, gambier, 65, 135
Cuticle, 23
Davy, Sir Humphrey, 47
Degreasing furs, 179
Diphenyl black, 152
Dip process, 98
Dressing of lambs, 52
rabbits, 54
moles, 54
Drum, 80
Drum-cleaning, 105
Drumming, 76
Drying-oils, 60
Drying skins, 71
Durability of furs, 5
Dyeing furs at higher temperatures,.
174
Dyeing of imitations, 93
- novelty shades, 92
- with aniline black, 144
coal tar colors, 171
mineral colors, 125
oxidation colors, 155
- vegetable colors, 128
Egg-yolk, 63
Emeraldine, 145
Enzymes, 51
Epidermis, 21
Erdmann, 155
Ermine, 5, 9
- bleaching of, 179
Fahrion, 48
Fat-glands, 21
Fats, animal, 59
Fermentation, 51
Ferrous acetate, 119
Ferrous sulphate, 119
Finishing dyed furs, 104
Fisher, 9
Fitch, 9, 94
Flat skins, 36
Fleshing, 41
- knife, 38, 42
- machines, 42
Flesh side, 22, 37
Formaldehyde, 63
chrome tan, 64
- tans, 49, 63
Formic acid, 44, 50
- as soaking agent, 39
Fox, black on, 140
188
INDEX
137
blue, 9
cross, 4, 10
grey, 10
kit, 10
red, 4, 5, 10
- dyed imitation silver fox,
1
- silver, 4, 10
imitations, 137, 143
- white, 11, 94
bleaching of, 179
French seal dye, 138, 144
Furamine dyes, 162
Fur beating machine, 80
Fur dressing, 30
Fur dyeing, 91
- difficulties of, 95
- with aniline black, 144
- with coal tar colors, 171
- with mineral colors, 125
with oxidation colors, 155
with vegetable colors, 128
Fur-hair, 24
Furriers' guilds, 34, 90
Furrol dyes, 166
Furs, colors of, 3
- description of, 7
- durability of, 5
of carnivorous animals, 37
- of herbivorous animals, 37
- quality of, 3, 4
- uses of, 1
- valuation of, 6
weight of, 5
Fustic, 134
shades with, 135
Gallnuts, 128, 132
Gambier cutch, 65, 135
Gelatine, 1, 25, 47, 48
Genet, 5
Glycerine, 63
Goat, 5, 11
- logwood black on, 141
Green's process for aniline black, 152
Grey-blue on white furs, 142
Ground water, 87
Guard-hair, 24
Guilds, furriers', 34, 90
Hair, 22
- action of acids on, 27
action of alkalies on, 28
action of salts on, 28
Hamster, 3, 11
Hardness of water, 87
Hare, 5, 11, 94
- black on, 140
- blue-grey on, 142
lynx dye on, 126
stone marten imitation on, 126
Hematein, 133
Hematoxylin, 133
Herbivorous animals, furs of, 37
Hudson seal, 144
Hydro-extraction, 40
Hydrogen peroxide, 168
- bleaching with, 182
Hydrosulphite bleach, 181
Hypochlorites, 184
Imitations, dyeing of, 93
Iron mordants, 119, 167
Iron pyrolignite, 119
Iron salts in tanning, 53
Iron tan, 58
Iron vitriol, 119
Kangaroo, 12
Keratin, 25
Kicker, 61
Killing, 98, 106
formulas, 108
nature of, 107
- purpose of, 106
- by brush process, 111
by dip process, 111
with caustic soda, 113
with lime, 112
- with soda, 112
Knapp, 46, 57
Knife, beaming, 38
shaving, 38
- fleshing, 38
Kolinsky, 5, 12
Krimmer, 5, 12, 13
Lactic acid, 44, 51
Lactic acid fermentation, 50
Lambs, 12
- dressing of, 50, 53
- dyeing of, 92, 140, 141, 142
Lard, 60
Lead, acetate, 126
189
INDEX
Lead sulphide dye, 126
Leather, definition of, 48
dressing of, 30
Leopard, 5, 13, 94
tanning of, 43
Lima wood, 135
Lime, 108, 110, 112
Linseed oil, 60
Litharge, 109
Loft drying, 72
Logwood, 133
- blacks, 139
shades with, 134
Lynx, 5, 13
- imitation on rabbit and hare,
126
Luster of hair, 23
Machines used in brush dyeing, 102
dip dyeing, 103
Marmot, 14, 68, 94
Marten, blending of, 91, 104
Marten, baum, 5, 14
- stone, 5, 14
- imitation, 126
Medulla, 22
Meunier, 46
Mineral colors, 125
- oils, 59, 63
- tans, 49, 53
Mink, 5, 14, 68, 94
Mole, 5, 15
tanning of, 54
Monkey, 15
Mordanting, 98, 114
Mordants, alkaline, 121
aluminum, 118
- chrome-copper, 167
chromium, 120, 166
- copper, 119, 166
copper-iron, 167
- iron, 119, 167
- tin, 121
Mucines, 25
Muskrat, 5, 15, 68, 94
imitation seal on, 144, 169
Neatsfoot oil, 60, 63
Neradol D., 64
Nigraniline, 147
Non-drying oils, 60, 63
Novelty shades, dyeing of, 92
Nutgalls, 33, 132
Nutria, 5, 15, 94
Oiling, 62, 77
Oils, drying, 60
non-drying, 50
partially-drying, 60, 63
Olive oil, 60
One-bath aniline black, 149
Opossum, 5, 15, 68
- black on, 140
skunk imitation on, 138
seal imitation on, 144
Otter, River, 5, 16, 94
- Sea, 5, 16
Over-hair, 24
Oxidation aniline black, 150
colors, 155
shades with, 165
Para-amido phenol, 153, 157
Para-phenylene diamine, 153, 157,
162
Partially-drying oils, 60, 63
Pelage, 2
Pelt, 2
Pernambuco w r ood, 135
Peroxide of hydrogen, 168, 182
Peroxides, 182
Persian lamb, 5, 12
dressing of, 50, 53
- dyeing of, 139
Physical theories of tanning, 47
Pickle, 49
Pigment granules, 23
Pony, Russian, 5, 16
Potassium permanganate as a dye,
127
as a bleach, 183
Protective-hair, 24
Pyrolignite of iron, 119
Quercitron, 135
Quinone di-imine, 163
Rabbit, 6, 17, 94
- imitation seal on, 144
- lynx imitation on, 126
- sable imitation on, 168
stone marten imitation on, 126
- tanning of, 54, 65
Raccoon, 6, 17
190
INDEX
black on, 140
- skunk imitation on, 170
Rain water, 86
Red fox, dyed as silver fox, 137
Redwood, 135
Rodol colors, 165
Russian tan, 51
Sable, 6, 94
American, 17
blending of, 91, 104
imitation on rabbit, 168
- Russian, 18
Salammoniac, 109
Salt, 32, 49
acid tan, 49
water soak, 39
Salts, neutral, 54
basic, 54, 115
Sawdust in drum-cleaning, 80
"Schrot-beize," 50
Seal, 6, 18, 94
- fur, 18
- dyeing of, 92, 144
hair, 19
imitation on muskrat, 138,
169
- -oil, 60
Shearing, 82
machine, 84
Shrinking-point of skins, 66
effect of chemicals on, 67
Silver fox imitations, 137, 143
Skin, 21
action of acids on, 26
action of alkalies on, 27
Skunk, 6, 19, 94
imitation on opossum, 138
on raccoon, 170
Soaking skins, 39
Soda ash, 110, 112
Sodium bichromate, 121, 166
- bisulphite, 127, 181
- chloride, 49
- peroxide, 182
- sulphite, 181
Soft water, 87
Softening skins, 38
Souring, 113
Squirrel, 6, 19
Staking, 78
Stannous chloride, 121
Stiasny, 64
Stone marten imitation, 126
Stretching, 78
machines, 78
Sugar of lead, 126
Sulphonated oils, 63
Sulphuric acid, 49
Sulphurous acid bleach, 180
Sumach, 128, 133
tanning with, 33
Surface water, 87
Sweat-glands, 22
Tallow, 60
Tanned furs, qualities of, 48
Tanning methods, comparison of, 65
Tannins, 32, 132
Tiger, 19
Top-hair, 24
Train oils, 63
Tramping machine, 61
Turmeric, 136
Under-hair, 24
Under-wool, 24
Ungreenable aniline black, 148
Unhairing, 82
machine, 83
Ursol dyes, 157, 165
Vanadium compounds, 147
Vat dyes, 177
Vegetable dyes, 128, 136
oils, 59
tans, 49, 65
Verdigris, 120
Water, hard, 87
soft, 87
Whale oil, 60
White fox, bleaching of, 179
Wolf, 6, 19
Wolverine, 6, 20
Wombat, 20
Wood dyes, 128
Yellow wood, 134
191
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