Rust prevention. A treatise on the preservation of structural steel used in bridges, buildings, fire escapes, etc., and sheet steel used in buildings, metal siding, roofing, smokestacks, boiler fronts, and standpipes, etc

UC-NRLF

T A

SB

LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA.

Class

Rust

Prevention

OF THE

f UNIVERSITY !

By

M. Stern

8ENEKAL

Copyrighted, 1907
By L. M. STERN,
Cleveland, Ohio.

OF THE
UNIVERSITY

OF

F(

RUST
PREVENTION

A TREATISE

On the preservation of Structural Steel
used in bridges, buildings, fire escapes,
etc., and Sheet Steel used in buildings,
metal siding, roofing, smokestacks,
boiler fronts, and standpipes, etc.

FOR

Anyone having in charge their mainte-
nance. Also property owners, architects
engineers and metal workers, etc.

By L. M. STERN

174580

INTRODUCTION.

The use of steel lias increased so rapidly within the
past ten years that the keen competition in cost of pro-
duction between the manufacturers thereof, has caused
an enormous amount of this metal (particularly in Sheet
Steel and Terne Plates for exterior use) to be thrown
upon the market, of a quality unsatisfactory to those who
have to shoulder the responsibility of its proper main-
tenance.

Since the advent of the Bessemer process of making
steel cheaply, the use of " charcoal iron " has compara-
tively decreased. Iron ore is very rarely reduced to pure
metallic iron for commercial purposes, consequently the
foreign substances which have not become eliminated
from it constitutes part of the material entering into its
transformation into steel.

The progress of disintegration of steel exposed to re-
actionary agencies largely depends upon the quality of
the metal, nickel steel, for example, being but very
slightly susceptible to corrosive action, while Bessemer
process steel being the reverse.

The intention of this treatise is to deal briefly with
the protection of the surface of the metal, so that cor-
rosive action may be prevented from exterior sources, and
in pursuing this course, we must of necessity carry on
the discussion with the understanding that the steel or
iron exposed to corrosion is of the quality which ordinar-
ily comes from the mill, leaving the question of placing
cheap and better steel upon the market for structural
purposes to those who manufacture it.

There are a great many paint manufacturing con-
cerns who make ridiculous and absurd statements in
their advertising matter, in the claims which they make

4

regarding wonderful properties possessed by a material
which they offer for sale to prevent corrosion and rust
on all kinds of metal work.

One large concern advertise that they are the sole
manufacturers who own a mine yielding graphite of
such a peculiar flake form that paint made with it pos-
sesses the wonderful properties of the flakes arranging
themselves like the shingles on a roof or the scales on a
fish, during the progress of painting a surface with it,
claiming as a result thereof, that " the flakes so arranged
would protect the oil in the interstices from evaporation
or excessive oxidation." This manufacturer fails to state
what form these scales would take if the painter would
forget himself and use his brush in the usual manner,
plying it back and forth on the surface so that the paint
would draw from both sides of the brush.

The property owner should post himself sufficiently
to be able to guard against deception and fraud. The
painter cannot be depended upon for any definite knowl-
edge of metal preservation. He either finds it unprofit-
able to waste his time thinking about the matter, or has
no inclination to have his paint cost him more than what
is absolutely necessary — hence his recommendations and
advice are more often given .than asked for.

Since the author's first treatise on this subject, pub-
lished in 1901, extensive practical tests of various pig-
ments and liquids for their protective durability have
been under his close surveillance 'in various sections of
the country, covering a wide range of climates. More
truths have been revealed regarding the most suitable
protective coating to resist the particular climate or
exposure at hand, and it is to be hoped that this treatise
will contribute enough light on this subject to induce
the architect, engineer or property owner (either having
charge of construction work or the maintenance of the
work after completion) to be more cautious in the selec-
tion of the most suitable materials.

5

The author desires it to be borne in mind that as his
livelihood depends upon the sale of all kinds of materials
for the prevention of rust, any influence or assistance
that the reader can extend toward their purchase from
him, will be duly appreciated, and that the same
judgment, resolution and practical experience which
prompted the issuance of this treatise will be devoted to
the interest of those so inclined.

Theories and the chemistry of paints will herein, as
far as practical, be avoided, and a strict adherence to
practical knowledge maintained as faithfully as possible,
so that the ordinary person, whether experienced or
otherwise, requiring some good general pointers on the
subject may find this treatise of some practical and
financial benefit.

Very truly yours,

L. M. STERN,

571 EAST NINETY-NINTH STREET, CLEVELAND, OHIO.

RUST PREVENTION.

Chapter I.

I run Rust and Its Formation.

Circumstantial evidence convinces us that iron at one
time, say thousands of years ago, might easily have been
or in fact was distributed over portions of the earth in
a metallic state and that the subsequent action of
oxygen, sulphur, silica and other elements have con-
verted it into the state in which it is now found and
which is commonly called iron ore.

Iron ore resembles rust in appearance and not only
contains the two important elements of rust, of which it
principally consists, namely (Fe2O3), but it contains
other elements as well, such as sulphur, and silica, &c. ;
hence it remains for man to undo what nature's labora-
tory has done for centuries and separate the elements
closely united in the composition of the ore and thus ob-
tain the metallic iron for use in the arts.

Rust is a reddish brown deposit, generally noticed on
the surface of steel and iron after having undergone de-
terioration by chemical change, due to exposure to agen-
cies, causing its formation. It ordinarily consists mostly
of oxide of iron, together with other minor substances
and water.

The compound known as oxide of iron consists of the
chemical combination of two parts of iron with three
parts of oxygen, commonly expressed in chemistry by the
symbol (Fe2O3) the first two letters representing the
Latin term Ferris, meaning iron and the letter "O repre-
senting the word oxygen.

For the reason that iron oxide is an hydroscopic salt,
it has the property of absorbing water, intimately holding
a portion of it in close affinity with its molecules : this,
however, does not change its chemical composition to any
appreciable extent, for the reason that the water does
not form a chemical solution with the oxide. Thus, rust
is termed a hydrated oxide of iron, which is symbolized
in chemistry as Fe2O3 + (H2O), which is oxide of iron

plus water. This water is free to act on metallic iron
into which it may come in contact, forming additional
rust, thus creating more room for water absorption and
continuing the process of rust formation indefinitely.

The chemical decomposition of the steel or iron by
the combination of particles of the metal with oxygen is
accelerated by frequent contact of the metal with oxygen
in a condensed form, such as is found in liquids, and its
subsequent evaporation in the presence of gaseous oxygen
such as atmospheric oxygen, &c.

Thus a solution of oxygen in the form of rain, dew
or other forms of moisture, when deposited on an iron
surface and quickly evaporated, will rust the surface
much more readily than if the water or moisture were
maintained on the surface. In high and dry climates,
where the proportion of pure oxygen is greater in the
atmosphere, iron and steel will not rust as quickly as in
low damp valleys, where fogs and heavy dews are preva-
lent, so that the conjoint action, of atmospheric oxygen
and water or other forms of moisture may act upon the
surface.

A piece of steel can be seen to rust in a few moments
time after the evaporation of water from the surface.
All forms of iron, whether sheet iron, steel, pig iron, cast
iron, malleable iron, or any condition of bare and un-
protected iron or steel surface exposed to frequent re-
newals of moisture and atmospheric oxygen, become
rusted, and the aggressiveness taken by this form of re-
agent depends not only on the frequency of evaporation
and renewal of moisture, but on the cleanliness of the
surface thus exposed and temperature of and active quali-
ties of the water, coacting with the atmospheric oxygen
as well, together with the chemical composition of the
steel, some grades of steel being attacked far more read-
ily than others.

The writer has seen steel girders on bridges so badly
rusted that portions of them, when coming in contact
with the pressure of the hand, would slough away like
a rotten log. Some rusted sections would be directly be-
low the coating of paint, which would be in an almost
perfect condition on the surface. This rusted metal would
be piled up in layers, one upon the other, completely af-
fected through the entire thickness of the original beam,
which upon examination would reveal the fact that the
steel had been imperfectly rolled or refined during the

8

process of manufacture, resulting in seams resembling an
imperfect weld, which would accumulate rust and by the
admission of moisture in the interstices and the contrac-
tion and expansion of the metal would loosen up the
crevices between the layers so that they could be rent
asunder with a pocket knife, like sheets of mica.

Steel kept under water, in the ground or set in cement,
which will admit oxygen and moisture and allow the
same to be evaporated, is eventually doomed to prema-
ture rust and decay.

All of the hydroscopic salts, especially common salt,
magnesium chloride, potassium chloride, ammonium
chloride aid and assist in forming rust.

Carbonic dioxide gas (CO2) which is constantly being
poured into the air from our chimneys and our lungs,
sulphuretted hydroge.ii from coke ovens and furnaces,
likewise attack the metal surface and assist in the for-
mation of the compound which we call rust.

.Water impregnated with caustic alkali will not rust
steel readily, provided the steel be immersed in a bath of
the same and be continually kept beneath the surface.

Almost all of the acids, when diluted with consider-
able water, rust iron and steel considerably, and strange
as it may seem the fact nevertheless remains, that a
great many acids attack steel more vigorously when di-
luted with water than otherwise. This fact may be due
to the oxygen in the water co-operating with the acid in
chemically decomposing the surface of the steel and con-
verting the same into rust.

Steel once rusted is more readily attacked, and its
decomposition takes place more readily than when in its
original condition, unless the surface has been divested
of all metallic oxidation prior to the renewal of the for-
mation of this compound.

The tensile strength of rust cannot be relied upon for
any practical purposes, and it is almost safe to say that
the amount of steel surface attacked by corrosion has
not only lost its equivalent amount of strength and is
burdened by the weight of the rust, but the factor of
safety is lowered to the basis of the weakest point
formed by corrosion.

The formation of rust may be classed as arising from
two different conditions, which we will assume for the
purpose of argument are:

Primary Condition. — Those conditions where the sur-

face has been exposed to ordinary rust generating in-
fluences, such as ordinary 'atmospheric conditions.

Secondary Condition. — Those conditions where tae
surface has been attacked either by substances attached
to the surface or by the action of extraordinary atmos-
pheric conditions. (Atmospheres impregnated with acid
fumes, &c.)

Rust can be economically removed very readily by
mechanical means, and this is the only means by which
it can be done on a large scale successfully. Abrasion and
hammering with a tool conveniently handled and ap-
plied to the surface is the method recommended by the
author. Flat surfaces that will admit of the use of a
steel wire brush should be gone over vigorously, both
lengthwise and crosswise, so that all loose scales and ir-
regular masses may become detached; then a hammer,
file and cold chisel should be brought into use, as well
as a painter's wall scraper or putty knife wherever there
is an accumulation of any thick incrustation. After this
treatment has been completely accomplished, the steel
brush should again come into play, as before, after
which a vigorous application of coarse emery cloth or
sandpaper should be employed, in lieu of which steel
wool or steel shavings may be substituted for the final
removal of all loose and scaly formations of rust.

After the above treatment is completed in as thorough
a manner as possible, a good heavy bristle brush should
be used to dust out the finely powdered rust, and then the
surface should be finally wiped off clean with a dry cloth.
The hot blast from a painter's torch may sometimes be
found to work to good advantage in evaporating as
much moisture as possible out of the* rust, which opera-
tion may result in reducing considerable of it into a
powdered state.

The use of the sand blast produces the best results,
but this is often too expensive a process.

Any vigorous treatment for the removal of rust may
be recommended in so far that the treatment thus af-
fected does not crack, break or otherwise injure the
metal nor leave any condition liable to impair the means
of protection afterwards to be employed.

. A wet process, or the various applications of oils, such
as benzine, gasoline, creosote oil has been recommend-
ed by many users of the same, and these may be used to
advantage to penetrate deeply into rust incrustations

IO

and thereby aid the hot blast from the painter's torch
in evaporating moisture, as heretofore mentioned. The
writer has not, however, found them to possess any
special beneficial chemical properties in rendering rust
inactive after the oil had evaporated therefrom. Oil
once eliminated from rust leaves it in practically the
same active condition as it would had it not been im-
pregnated or covered with it.

The author has found one advantage, however-, in
soaking powdered rust with oils immediately prior to
its removal, and this is that the rust is capable of ad-
hering to a cloth when rubbed on the surface thus oiled,
forming a sort of coagulated mass of rust paste, which
may be used to great advantage in contributing friction
or grinding properties, much after the fashion of the
old style "bath bricks," which were used to clean and
brighten rough table ware.

We have observed the reasons why rust forms, and
we will henceforth turn our attention to the measures
whereby the accumulation of rust may be prevented : in
other words, the ways and means whereby steel and iron
may be maintained or kept free from contact with
oxygen and atmospheric moisture. The ways and means
by which the same may be done is, of course, to cover
the surface with a noncorrosive substance; something
which will not contain nor transmit any oxydizing me-
dium to the surface of the metal. It must, therefore, a*
far as possible (for all practical and economical reasons),
possess the qualities of easy application, maximum
amount of protecting durability and a minimum amount
of cost.

I i

Chapter II.

Some Chemical Elements and Their Symbols.

By chemical element we mean those substances which
are not made up of two or more substances. They are
not necessarily distinguished by any external appear-
ances, but are known to science as substances which can-
not be decomposed. We can convert them into thousands
of other substances, but in all cases extra weight and
material has been added, but none taken from an element
composing a compound.

For illustration, we may decompose water by an
electric current, first weighing the water. The hydrogen
and oxygen that become separated we know were in com-
bination, and the weight of both together equal the
weight of the water, for on combining them again we
may thus prove that water consists wholly of hydrogen
and oxygen.

A nice illustration of the combining of two elements
may be shown by the burning of finely pulverized metal-
lic iron in the presence of oxygen. The result of a change-
is a substance which we call oxide of iron. This sub-
stance obtained has increased in weight, proving that ma-
terial has been added to it, and not taken from it, the
extra weight being due to its combination with oxygen.

This experiment illustrates a most remarkable truth
in regard to the substance we call iron. By various
chemical processes we can produce from the metal hun-
dreds of different substances, but, in all cases, the con-
dition of the experiment and the relative weight of the
products prove that material has been added to the iron
and not taken from it.

By no chemical process whatever can be obtain from
iron a substance weighing less than the metal used in its
production. In a word, we can extract nothing from
iron but iron ; in like manner we cannot extract anything
from carbon but carbon, nor, in fact, any material from
any element but part of the element itself.

In chemistry the initial letters of the Latin names
of elementary substances are represented to denote one
atom of each element. These are callerl chemical syin-

12

bols. The symbols of these elements, which sometimes
enter into the composition of paints, oils or varnishes, or
compounds entering into the destruction of the same
while under exposure, are as follows:

Aluminum Al. Manganese Mn.

Barium Ba. Mercury Hg.

Calcium Ca. Nitrogen N.

Carbon C. Oxygen O.

Chlorine Cl. Potassium K.

Copper Cu. Silicon Si.

Hydrogen H. Sodium Na.

Iron Pe. Sulphur S.

Lead Pb. Zinc Zn.

Magnesium Mg.

The full list of elements are set forth in almost any
work on chemistry. Those not here mentioned are omit-
ted for the reason that they are rarely, if ever, met with
within the scope of the subject here at hand and would
only have a tendency to burden the reader with unneces-
sary and uninteresting complications.

Chapter III.

Rust Prevention.

Since we have noticed that the exidation, rusting or
corrosion of iron is due to its chemical combination with
substances with which it has uniting properties, and that
the resultant product is what we call rust, primarily con-
sisting of Fe2O3 + (H2O), we necessarily conclude that
we can only prevent the formation of this compound on
the surface of the metal by maintaining its isolation
from substances necessary for its propagation, thus reach-
ing the foundation of its protection.

There are many ways and means of accomplishing
this, and innumerable substances may be used for apply-
ing on the surface of the metal, all of which have widely
different characteristics, and also great variation of
permanency or efficiency ; but we are interested chiefly
in the most economical and reliable method of doing so.

We know that water (H2O) and atmospheric oxygen
alternately acting on the metal surface are the most
prevalent rust generating mediums, causing rust, and
therefore should expect to obtain materials for applica-
tion on the surface of the metal that are not easily af-
fected by these agents, or the mediums which cause the
secondary condition to produce rust.

The efficiency of protective coatings for metal sur-
faces are entirely dependent upon the character of ex-
posures, adhesiveness of the coatings, resistance to abra-
sion, and other qualifications, in consequence of which we
are led to investigate the various conditions in order
to meet them in the most economical and convenient
manner possible.

Oils and greases of various kinds have been used for
protecting metallic surfaces from the absorption of oxy-
gen. Great varieties of them are used where the ex-
posure is not permanent or severe, and the oils or greases
are to be removed easily after they have served their
purpose; for example, machinery, firearms, carpenters'
and mechanics' tools, &c., and even these, if left out in
the rain, will become rusted soon after atmospheric
conditions or water obtains the mastery over the coat-

14

evaporation or decomposition. The question, however, of
ing, causing its washing off by friction or elimination by
temporary prevention of rust by the use of oils and
greases is of small importance compared to the protec-
tion of costly steel and iron structures and other large
metal surfaces, and consequently these will engage our
attention so that the selection of the proper materials for
thie production of protective coatings may be accom-
plished in the manner most desired.

Various paints, oils and varnishes may be used, and
their protective qualities will last as long as they will
be devoid of water absorbing properties, and m&intain a
coherent adhesive coating on the surface.

The author has ascertained by actual tests that there
exists a wonderful variation in the aggressiveness of
various pigu-ents coacting with atmospheric moisture in
attacking a metal surface, when the oil has dried out,
leaving the paint porous enough to absorb moisture. It
svill then be seen that a destructive agent finally en-
sues from the material which was originally intended for
a protective addition to the oil.

Very often an oxide paint pigment is mixed writh oil
and used as a protective coating for metal. The oil
neutralizes temporarily the oxidizing properties of the
pigment in question, but when the dried paint becomes
porous by the disintregation, excess oxidation, or evapora-
tion of the oil, the oxide pigment takes up moisture, car-
ries it to the metal surface and there conducts a process
of conjoint attack in generating rust that would not be
possible with a carbon pigment used under similar con-
ditions.

Porosity of a paint can often be detected by the ap-
pearance of stains from moisture with which the paint
becomes saturated, and by cutting into the moistened
paint with a pocket knife a fair idea may be had as to
whether a fresh application of paint is necessary to pre-
vent moisture from gaining admission through the coat
ing and coming into direct contact with the metallic sur-
face.

The porosity of a paint, however, is very rarely taken
notice of in time to prevent rust, as it often, while in
this condition, appears to remain a coherent, adhesive
mass of fair density and resistance to mechanical abra-
sion. The most noticeable feature which may be easily
discerned in this respect, however, is that the coating

has lost its glossy appearance, and appears dead or dried
out, and even in this condition it is not always porous
enough to admit moisture entirely through the coating.

The illustration shows what can be done in the
laboratory to definitely ascertain the amount of porosity
of any kind of paint or varnish. Owing to a chemical
phenomenon, any dried coating of paint having been ex-
posed to the weather any number of years may be by
the author easily removed from the metal surface intact
and without injury. The paint thus removed can be ac-
curately tested for porosity, elasticity and adhesiveness.

Plate I.

and the thickness of it may be tested at different points
with a micrometer or depth gauge.

A simpler and more satisfactory way of testing or
ascertaining porosity of a paint film for the ordinary
person, however, would be to apply the paint on sheets
of glass, expose the same to the weather for from one to
five years at a convenient place, so that the sample may
be taken down and held up to the light at different stages
of exposure, and thus any ordinary amount of porosity
can be very readily seen.

Paints or varnishes intended chiefly for decorative

16

purposes, that will l#st for 15 years on the inside wood-
work of a residence, will do well if they last more than
five years on the outside woodwork of the same resi-
dence, and would be an exception, indeed, if they would
last over two years on the tin roof or gutters, thus demon-
strating the great difference in exposure and consequent
variation in the decomposition of the paint on different
portions of a house.

It remains for us, therefore, to compound paints for
specific purposes, made of such material that will give
them the greatest efficiency. Knowing why, \vhere and
when the different materials necessary for their composi-
tion may be used to the best advantage, not, however,
taking for example the various materials used to pre-
serve or beautify wood, for while one class of paint may
be suitable to both wood and metal, this condition would
merely be an incident when atmospheric or other severe
exposures would prevail.

In a majority of instances paint dealers throughout
the country sell most of the paint intended for wood
surfaces from $1.25 to $1.50 per gallon. Yet, when it
comes to paint for metal roofs, the prevailing condition
seems to be that the dealer canot sell a paint for this
class of work for more than 50 or 75 cents per gallon.
Why? Because the uninformed possessors of false eco-
nomical paint principles believe " If the paint on the
visible exterior of the house, which is expected to look
pleasing to the eye, cost a certain price, paint that is put
up on the roof and which is not necessary to look pleas-
ing to the eye, should not cost half that price." There-
fore, the price that controls the quality of paint on the
market for metal roofs which are sold by the dealer are,
unfortunately, kept down by popular demand.

Another reason for a vast amount of cheap trash on
the market for metal protection and called paint is the
fact that the painter or tinner applies a cheap quality
so that his own temporary profits may be thus gained.
Painters and tinners invariably are asked by their cus-
tomers for prices "per square" for doing the job (de-
tails of quality and materials omitted), and in order to
secure the work he is tempted to make a price consistent
with his chances of a successful issue. As a rule the
tinner does not care much whether the paint he puts on
wears one or five years. It makes no material difference
to . him. It may present a good appearance for a few

17

months after it is applied, and be almost entirely washed
off in a year or so afterward.

There are many paints that will wear well for a
period of from 5 to 10 years on sheet metal exposed to
the weather, and also on bridges, but the manufacturers
of these are compelled very often to give a very close bid
in order to get a contract and are compelled to use cheap
material ; in fact, they have often made the statement to
those who attempt to sell them high grade paint that
" our customers will not pay us any more for our ma-
terial with high grade paint than if it were coated with
the cheapest that could be obtained."

l«

Chapter IV.

Paint Ingredients, their Classifications and Functions.

Paint ingredients we shall divide into two general
classes, namely: Liquids and Solids. They consist of
the following:

1. Pigments — (dry powdered, insoluble substances).

2. Vehicles — (Liquid materials for carrying the pig-
ments).

3. Volatile oils and dryers — (Evaporating oils, &c.)-

4. Soluble Solids — (Solid substances for dissolving
into the liquids .

Pigments (for paints) are those dry powdered sub-
stances intended for mixing with liquids for the purpose
of making liquid or paste paints.

All pigments when dry hold water freely.

The pigments used in metal preserving paints are all
derivatives of minerals, on account of their cheapness
in price, stability and durability, while those pigments
which are made of vegetable and animal products are
used for artistic and beautifying purposes.

Pigments are generally termed " dry colors," but this
term is erroneous, for the reason that many pigments do
not possess -any color, being merely white or black. They
are likewise termed " dry paints " which term is am-
biguous, for the reason that dry paint is often the sub-
stance which results in a liquid paint becoming dry on
a surface.

The definition of the word pigment, as above stated,
in order to avoid confusion, should be well kept in mind.
Pigments we separate into two classes : — Natural pig-
ments and chemically produced pigments.

Those which are used in the manufacture of pro-
tective coatings are, as follows:

Black pigments.

White pigments.

Yellow, red and brown

Graphite, C
Lamp black, C.

White lead, 2PbCOs,
PbH2Oc.
Oxide of zinc, ZnO
Zinc white, ZnO
Lead sulphate, PbSO4.

Whiting, CaCO3
Barytes BaSO4

Yellow ochre, Fe2HO6

Umber, Fe2HO6+MnHO4
Iron oxide, FeoO-,.
Venetian red, FeoO3+
impurities.
Red oxide, Fe2O3 + im-
purities.
Red lead Pb3O4

Barium sulphate, BaSO

Metallic ' red, Fe2O2 +
impurities.

While there are many more pigments used than
these mentioned for metal preserving paints, the balance
of them are generally used for their coloring properties,
or as a means of deceiving purchasers by false state-
ments, as to extraordinary merits, which they are pre-
sumed to possess.

The function of a pigment is to thicken the vehicle,
to make it opaque with a suitable material or color, to
give the paint a viscid body (viscosity) and add tough-
ness and durability to the paints when dry. Some pig-
ments accomplish this with a great variety of results,
especially when more or less of it is used than the
amount necessary to perform its maximum amount of
usefulness. The exact amount of pigment or pigments
to be used in making a paint to possess the proper thick-
ness when spread on a surface to obtain the greatest ef-
ficiency in its protection can only be ascertained by ac-
tual tests for their proper working qualities under the
brush, and also withstanding the kind of exposure met
with.

Actual tests for the durability of the pigment are
necessary in determining the quantity of the pigment to
be used for the reason that there is such a variety of
grades of pigments on the market, and they possess an
individuality of certain capacity for absorbing or " tak-
ing to" the oils used; that no set rule can be laid down
for the actual amount to be used necessary to accom-
plish the best results.

This is especially true for the reason that one manu-
facturer's pigment is at variance in texture, freedom
from impurities and other qualifications, from another's
which bear the same name.

Each class of pigments has a different effect upon
the drying or oxidizing properties of linseed oil : Some of
these pigments retard the drying properties while others
hasten the oxidation to a remarkable degree.

Among those of the latter may be mentioned all of
the pigments containing oxygen in their composition.
Red Lead (Pb3O4) especially. The pigments which con-
tain oxygen prevent the formation of rust, while they
are in combination w^ith oils, but when the oils either
evaporate or become excessively oxidized so that the
pigments protrude through the film of oil on the dried
painted surface, or in fact loses so much of the oil
through exposure that the paint has become porous, it

20

then co-acts with moisture and atmospheric oxygen and
the metal surface beneath the paint becomes rapidly and
vigorously attacked, whereupon the very pigment which
was originally a protective medium becomes a rust pro-
ducer.

The carbon pigments are elements and consequently
can only consist of carbon excepting where there is an
impurity or an adulteration present and this is not as
a rule premeditated, but rather accidental, at all events
they are not generally found to any such a degree as
they are in the lead or chemically produced pigments
and even when not so the impurities in the former are
invariably inert substances and do not promote chemical
activity in producing rust.

The carbon pigments show a far superior resistance
to the accumulation of rust, when the oils begin to wear
out or become eliminated from a painted surface after
prolonged exposure than do the oxygen pigments, more-
over they are not affected to any extent by acids whether
in the liquid or gaseous form. Hence, it will be seen
that the carbon pigments are to be preferred, graphite
especially, for graphite which is also ^sed as a lubricant
possesses such a degree of fineness of texture that it
gives the paint where it is used as a pigment, such a
slippery surface when several years dry, that it reduces
to the minimum the abrasive effect of water, snow, ice or
mechanical abrasion, etc.

We may easily destroy the efficiency of the best
pigment by the use of admixtures whereby the' pigment
or the oil become impaired. A course granular sub-
stance added to graphite tends to give to the painted
surface a rougher coating of paint which serves as a
lodging place for water, which adheres by capillary at-
traction to the roughened surface.

Pigments as powdered dry substances are fixed or
stable bases, but as coloring materials (excepting the
carbons) they invariably fade after prolonged exposure,
and while their stability as a base may be relied upon,
the various effects which the different pigments possess
in their co-active properties with drying oils is more or
less important. It is not so important however, as the
proper treatment of the oils to be used.

The most undesirable pigment mixed with the most
desirable liquid material would make a fairly good paint
compared to reverse conditions. The complex functions,

21

careful preparation of, and extreme sensitiveness of the
liquids, necessitate a knowledge covering a much wider
field of experience.

Moreover, pigments have less latitude in their func-
tions and present opportunities of physical examination
for requirements that are easily and finally determined.

Neither heat nor cold affects pigments to any unde-
sirable extent, — graphite, Venetian red, red oxide, yellow
ochre, umber and many others being fire-proof to the
extent of readily withstanding temperatures, many
times higher than that necessary to produce a red heat
on steel. They are also acid proof to the extent of
not being affected by the most effective acid fumes or
gases that are possible in open atmospheres.

Many deceptions on this point are practiced upon
the public by dishonest manufacturers, who claim or
infer originality in that they have a fire and acid proof
pigment, when in fact the majority of the most frequent-
ly used and cheapest materials for this purpose possess
these features.

Deceptions are practiced to such an extent with
graphite that many interested persons looking forward
to the purchase of paint containing graphite as a pig-
ment ask the question, " Where do you get your
graphite?"

This deception arises from the fact of various manu-
facturers, convincing prospective purchasers that they
own or control graphite mines which produce graphite
of incomparable purity, or peculiar qualities not possi-
ble with any other.

It will be seen that the question of selecting pig-
ments that will withstand heat, cold, and acids is a
simple one, and that the white and colored pigments
contain oxygen which when combined with a drying oil
hasten more or less the oxidation of it, and that no risk
whatever may be run in the selection of inert pigments,
such as graphite or lampblack in the choice of the best
and most protective mediums to be mixed with oil for the
production of the most effective protective coating for
metal surfaces.

The liquids used in paints are compound substances.
They are not fixed or stable, and they constitute ve-
hicles susceptible to .decomposition, vitally affecting the
durability of the film of a protective coating and therein
lies room for constant investigation and improvement.

22

Vehicles are those liquids which are used with pig-
ments to carry them in a fluid form for convenient ap-
plication on the surface for which it is intended.

The functions which vehicles should perform in pro-
tective coatings for metal should be that they should
have a close affinity with the pigments with which they
are mixed and form a dry, waterproof and durable non-
porous coating, one that will not chemically deteriorate
the metallic surface on which it is applied. Certain oils
have been found to possess the greater amount of these
functions and those oils which dry on a surface by co-
agulation due to oxidation are being used for the pur-
pose.

The oils which dry or coagulate by oxidation are
not numerous, but their extraction, purification and sub-
sequent treatment are very important, demanding a
large amount of technical skill : these oils are more or
less viscous varying considerably with the process and
care taken in their preparation.

The value of an oil for use as a vehicle depends al-
most entirely upon its durability when dry : thus oils may
be divided into two classes, the fatty oils, and the vola-
tile oils, or evaporating oils.

The fatty oils are greasy and are incompatible with
water ; when oil and water come together they do not
mix, (excepting when mixed with strong acids or al-
kalies) water running over a fatty substance does not
wet its surface. This property is therefore useful for
oil paints, for surfaces coated with an oil paint made of
fatty oil and pigment are protected from the destructive
action of water.

Those fatty oils which when exposed to the at-
mosphere, after being spread on a surface, become solid
and coagulate into a varnish like coating, are known as
drying oils and are distinguishible from the non-drying
oils in that the latter remains either fluid or greasy for
an indefinite period.

Among the drying oils the best known and most
commonly used are linseed oil, poppy oil and Chinese
wood oil. Poppy oil and Chinese wood oil, however,
are not only too expensive to use for the manufacture
of protective paints, but they do not possess sufficient
durability over linseed oil to warrant the excess cost
necessary for their use. All other drying oils either

23

dry so slowly or imperfectly that they are undesirable
compared to linseed oil.

The drying power of oils is directly proportional to
the amount of oxygen they are capable of absorbing, and
if the absortion of oxygen is not checked the oil becomes
over oxidized and loses its tenacity and cohesiveness.

The increase of drying properties of linseed oil is
accomplished by extracting impurities which chiefly con-
sist of cellular tissue and albuminous matter, etc. It is
usually done by storing the oil in large tanks allowing
the impurities to settle to the bottom after which the oil
is drawn off, leaving the sediment behind. The oil is
then clarified by passing through a filter press.

To further increase the drying properties of linseed
oil it is boiled in the presence of manganese dioxide,
manganese borate, red lead, litharge or other substances
and raised to a temperature high enough and main-
tained long enough to impart the proper requirements
to it. The treatment of linseed oil requires such a great
amount of skill and experience, and the various forms of
treating the same are so many that the study of it for
a lifetime would develop new experiences continuously.
Therefore, the treatment of linseed oil will not be dis-
cussed at length here.

When linseed oil dries it is called "Linoxyn" (Lin-
seed oil + Oxygen) for the reason that it forms a perfect
chemical union with oxygen and is th'en converted into
the solid material thus named.

Linseed oil expands during the period of absorbing
oxygen until it becomes thoroughly dry, after which the
swelling up very gradually subsides. The expansion
takes place to such a great extent that it is not only
readily perceptable by appearance, but a difference in
weight can be easily ascertained owing to the very large
proportion of oxygen consumed in the process.

Almost any one familiar with linseed oil knows that
after the drippings from a linseed oil can falls onto a
piece of glass or other non-porous surface, it begins to
thicken as it dries.

The formation of a paint or oil skin on the top of
liquid linseed oil paint exposed to the atmosphere is thus
easily accounted for as being a formation of linoxyn. It
will be noticed furthermore that a linseed oil paint skin
becomes crinkled on the top, and this is due to the ab-
sorption of more oxygen on the surface where contact

24

is had with atmospheric oxygen, than can be ad-
mitted farther below the surface thereby causing ex-
pansion on the top greater than the wet side of the skin
which lies underneath. Gradually the paint skin admits
more oxygen until the linoxyn gets thick enough to re-
tard the progress of absorption, and reaches a point
where it seems to cease.

It will be seen that pigments mixed with linseed oil
cut down the percentage of linseed oil in proportion to
its bulk, for the formation of linoxyn, and the subsequent
clogging of the pores in the linoxyn by the pigment
(which, if graphite, does it to >a greater degree than the
coarser pigments) renders the linoxyn for a limited time
less porous than if the oil were not combined with the
pigment; provided, however, that not more pigment be
used than the oil will properly envelop and carry with
it.

It will be noticed, moreover, that a fresh dried lin-
seed oil paint film (without a volatile oil admixture) is
thicker than when the coating was in the wet state. This
causes the oil to expand and protrude above the pigment,
thus exposing the protruding oil to direct attack of dis-
intregating influences, while protecting the pigment at
the same time. Shortly after the linseed oil becomes
dry and reaches its fullest extent of expansion it begins
to subside and to lose its gloss, on account of becoming
porous, and also for the fact that it becomes excessively
oxidized and worn down to the pigment ; at this stage
oxidation and disintegration of the vehicle is retarded or
accelerated according to the nature of the pigment, which
if carbon accomplishes the former, and if oxygen pig-
ments the latter. Hence, it will be seen that the organic
matter of a paint which is the vehicle, is the unstable
and highly sensitive portion of it that requires the most
important and careful treatment.

The volatile oils used in paints are those generally
called terpenes in chemistry. They usually belong to
one of the groups of hydrocarbons having the same or a
similar composition as turpentine (Ci0H16), they are
highly inflammable and when dropped upon a sheet of
glass and exposed to the atmosphere for a short time
completely evaporate. The function of a volatile oil in
paint is either to adulterate the linseed oil, lessen the
viscosity of the paint, cause the paint to flow more freely
so that a thin and consequently quick drying paint will

25

ensue, or for the purpose of dissolving gum resins so as
to make a quick drying varnish, sometimes used as, (and
erroneously called) a dryer. In this case the volatile
oil evaporates from the resin leaving a thin coating or
deposit of the resin of the same character practically as
it was before being dissolved into the volatile oil.

The volatile oils usually employed are benzine, petro-
leum naphtha, coal tar naphtha (sometimes called creosote
oil), benzole and turpentine. When these are used to
any extent in linseed oil, paint not having a solid com-
position in solution with the oil, the paint loses consider-
able of its value. The pigment will separate from the
oil freely and precipitate to the bottom soon after being
mixed with the oil, the viscosity and adhesiveness of the
paint would be impaired, the coating would be too thin
to give ample protection and porosity would result imme-
diately after the evaporation of the volatile oil from the
painted surface, thus defeating the very object of a pro-
tective coating and rendering the coagulated mass of
dried paint less efficient and durable.

Metal surfaces defy the absorption of paint to such a
deg'ree that the admixture of a thin or volatile oil for the
purpose of creating a penetrating paint is useless. Hence,
the lack of necessity of using a thin priming coat, which,
if used, would run down in streaks on a vertical or in-
clined surface.

On the other hand, should the paint be made quite
thick by the use of the pigment it will be done at the
expense of the vehicle and its adhesiveness, as there will
not be sufficient vehicle to carry the pigment over the
surface to be painted, and leave a glossy oily finish.

Protective coatings for metal should be heavy bodied
by the use of a heavy bodied vehicle and should be sticky
enough in the liquid state to take to the metal freely
from the brush. It should be capable of being brushed
out thin or flowed on thick before it has time to set and
should not run on a vertical surface when thus applied.

It should be quick setting but slow drying ; the former
to withstand unexpected rain storms shortly after appli-
cation, and the latter to prevent premature hardening to
a state of brittleness, not consistant with sufficient ex-
pansion and contraction of the metallic surface due to
extreme changes of temperature, which on a dry paint
film averaging one two hundredth of an inch in thickness,
would not be inconsiderable.

26

:«iVER3ITY )

J

.c4LlFORN\fe/

Soluble solids, as their name implies, are those solid
materials which, when melted into a liquid state, are
capable of being dissolved into the oils for the purpose of
creating a compound vehicle or a varnish.

Varnish gums are soluble solids and so are tars,
pitches, asphaltums and also prepared compositions made
for the purpose; all of which have various and diverse
qualifications for use in paints and varnishes for specific
purposes, and a knowledge of their characteristics are
necessary in order to select the proper ones for their ade-
quate use.

The functions of soluble solids, in protective linseed
oil paints, are to impart to the oil quick setting, adhesive
elastic properties, viscosity and durability by way of
protecting the linoxyn from over oxidation, and that
state which is commonly called the " chalking off " condi-
tion of the pigment in the dry paint in which state it
reaches the point where it has ceased to be a protective
coating. The prolongation of the protective qualities of
an oil by the use of a soluble solid depends entirely upon
the character of exposure, together with the proper
amount of, and character of, the soluble solid to be used
in the oil, and also the quality of the oil to be used. The
boiling down of linseed oil to a thick sticky consistency
does not take the place of the proper sort of soluble
solid, for the reason that it will not " take to " a suf-
ficient quantity of pigment, neither will it allow of the
production of free and easy spreading qualities. Further-
more, the oil thus treated does not delay excess oxidation,
which is the feature most desired.

The progress of oxidation of linseed oil paints, not
having a soluble solid, may easily be noticed after fre-
quent rain-storms, dews or other forms of moisture have
become evaporated soon after contact with the dried
paint (similar to the action necessary to rapidly produce
rust.)

The paint loses its gloss, becomes dried out eventu-
ally ; so that the only perceptible part of the paint which
is left is the pigment. All of these characteristics develop
to a degree, proportionate to the frequency with which
the applications of moisture on the surface and its com-
plete evaporation therefrom has been accomplished.

A soluble solid to counteract these defects should be
insoluble in water, but soluble in linseed oil, it should
be solid yet elastic in its basic state and maintain this

27

condition without perceptible change; withstanding as
large a variation of temperature as possible, it should
not absorb oxygen nor become perceptibly effected by it,
and when dissolved into the oil should form a compound
vehicle which will effectively combat the attack of water,
heat, cold, oxygen, sulphurated hydrogen gas, carbon-
dioxide gas, and to a great extent the effects of the
oxide pigments when the same, of necessity, have to
be used. It should not impair the proper drying quali-
fications of the oil; that is not allow the coating to re-
main tacky or sticky for a long time after it is applied,
and when necessity requires it, it should allow of suf-
ficient volatile oil in combination to allow the paint to
spread freely and set tough enough in a few hours to
withstand the deleterious effect of unexpected rainfalls,
and possess an amount of cohesiveness that the viscous
mass of solid soluble material will flow together while
the evaporation of the volatile oil takes place, leaving the
surface tough, elastic, smooth and waterproof, thus elim-
inating the defects possessed by all of the straight oil
paints where volatile oils are used.

The proper use of a soluble solid in linseed oil paints
intended to prolong the life of a protective coating for
metal has heretofore been but very feebly attempted by
paint manufacturers. Rosin and some of the black
pitches are often used, and these are used mostly as
adulterants, or to add a temporary glossy appearance at
the expense of the durability of the paint which con-
tains it.

There has been little or no demand for the use of
soluble solids in the composition of oil paints for the
reason that the public has not known the benefits to be
derived from the use of it. The extra cost necessary for
its addition to paint, together with the difficulty of ob-
taining one possessing the requisite physical and chemi-
cal requirements which can only be ascertained after
exhaustive and tedious tests covering years of experi-
menting, have induced manufacturers of protective coat-
ings to abandon this feature in the composition of their
products, and as a result almost all of the protective
coatings now on the market with any claims to being
high grade are straight oil paints with the omission of
SL soluble solid in their composition.

Those paints which are not of recognized standard as

28

being high grade often have rosin, pitch or a cheap rosin
dryer in their composition.

The writer has been confronted with these facts for
many years, and after an exhaustive system of experi-
ments has succeeded in converting by a chemical phe-
nomena in the use. of chlorine gas, an oil of vegetable
origin which has no drying or oxidizing properties, into
a solid rubber-like mass of a light yellow color, complete-
ly converting the vegetable grease or fatty matter into
a new substance, which, when melted (necessitating a
heat of 600 degrees F.) turns black, flows like oil and
is perfectly soluble in boiling linseed oil, becoming part
of the vehicle itself and incapable of mechanical separa-
tion therefrom.

This soluble solid composition has in the past five
years proven to be the missing link needed to produce
a protective coating of the highest efficiency in every re-
spect, and it is with pleasure to the writer that a pro-
tective coating with over twice the durability of anything
yet produced for a top coat, of the highest efficiency is
now produced and offered to those who are interested
enough in this subject to demand it for their use.

The writer has become acquainted with paints that
were represented to contain rubber (caoutchouc) and has
personally made paints with this material. Manufactur-
ers of so called " rubber paints " claim that the rubber
contained in their paints make the paints more adhesive
and elastic, thereby extending the life of the paint, by
reason of its lessened liability to become hard and brittle
and eventually crack.

The extreme high price of rubber, notwithstanding
the small amount needed on account of its property of
swelling up considerably in the oils into which it may
become dissolved, makes its use in paint prohibitory, fur-
thermore as a paint material it is worthless.

The author, as well as all manufacturers of rubber
goods, know that oxidizing oils, or oils used in the manu-
facture of paint, will rot the rubber shortly after ex-
posure to the weather, and when it has become dry on a
surface its shrinkage opens up large crevices and the
balance of it becomes crumbly, resembling a condition of
dry rot. These circumstances clearly demonstrate that
rubber has absolutely no value in paint and that the use
of it in this respect not only entails a useless expendi-
ture of money incidental to its cost, but also the cost of

29

applying a paint containing materials which tend to cur-
tail its efficiency.

In all cases investigated, however, the manufacturers'
claim to using rubber, either new or old, in painvr has
proven to be a deception in order to obtain a high price
for a coal tar product, or one no more costly in its pro-
duction than one of this sort.

We have noted in the foregoing pages the functions
of pigments, vehicles and volatile oils, and it will be ob-
served that their action, while in combination as a pro-
tective coating, is more or less definitely understood.
Not so, however, with suitable soluble solids, for as
stated, none but deleterious hard brittle rosins, tars or
pitches (or if they are not hard and brittle to start with
they soon get that way under exposure) have been used
and the author has no hesitancy in saying that he who
solves the problem of intelligently compounding a solu-
ble solid composition that will definitely double the life
of linseed oil as a vehicle in protective coatings without
increasing its cost, unlocks some of the secrets of chem-
istry, which, without doubt, is an acquisition of no slight
value.

Chapter V.

VARNISHES.

Their Bases and Characteristics.

The line of demarkation as to what constitutes a var-
nish for a paint has been more or less confused where the
varnish is not transparent and where the paint has a
varnish vehicle. In order to avoid confusion we shall de-
fine a varnish as a liquid substance, not containing a
pigment, which is capable of drying on a surface over
which it has been diffused to beautify or protect the
same.

A varnish may consist of a drying oil, a drying oil
with a soluble solid base, or a volatile oil with a soluble
solid base or the combination of any or all of these into
one.

The drying oils we have mentioned on page 2.'i, some
of the soluble solid bases for varnishes are those men-
tioned on page 27, and the volatile oils used are tho'se
mentioned on page 20.

Varnishes may be either transparent or opaque, and,
when the latter, they are generally . black, such as tar
varnish or asphaltum varnish, &c. The transparent var-
nish bases consist of common rosin, which is the residue
left in the stills after the distillation of turpentine, or
resins, originating by their exudation from various spe-
cies of trees, some of which have disappeared centuries
ago, leaving the resins embedded in the soil, and include
mastic dammar, Sandarac, copal, kauri, and many others,
all of which contain carbon, hydrogen and oxygen, and
are very brittle at ordinary atmospheric temperatures
and melt at temperatures ranging from 200 to 500 degrees
F.

When they are combined with linseed oil or linseed
oil paints they impart considerable viscosity and adhe-
siveness to the paint while in the liquid state, and when
the paint becomes dry higher gloss and better finish, but
after prolonged exposure to the atmosphere on a large
metal surface subjected to considerable heat from the
sun's rays, where rapid radiation of the heat and sudden
cooling off of the metal causes considerable contraction

31

and expansion to take place; the paint rapidly becomes
badly cracked and loses its adhesiveness.

The increased viscosity and adhesiveness of the liquid
paint is not only lost in the dried paint, but it rapidly
becomes very hard and brittle. This brittleness is due
to the evaporation of the volatile matter in the paint or
the excess oxidation of linseed oil in which a brittle solu-
ble substance has very little lasting effect.

Pigments in combination with a resin or pitch tend to
excessively harden them when they have become dry, and
thus it will be seen that the separation^ of a pigment from
a resin or pitch varnish is an advantage where great
variations of temperatures are to be met with.

The pitches which are used in many of the so-called
protective coating are coal tar pitch, asphaltum pitch and
petroleum pitch, &c., and these go under so many differ-
ent names, in order to hide their indentity from pur-
chasers that it would be impossible to keep track of the
new names, which are invented to deceive the unwary.

These pitches have to be made into very hard brittle
substances by cooking them in kettles before adding the
oils, otherwise their foundation as a base would not be
solid enough to allow the substance to harden on a sur-
face and become dry.

When pigments are added to a soft pitch with a view
to causing them to dry it not only augments the lack of
toughness, but serves to detract the stickiness from the
pitch, for the reason that pigment alone has no viscosity,
being a dry substance. Therefore when pitches are to be
used they should be used in varnishes only, if they are to
impart their full value to a coating intended for protect-
ive purposes.

The melting point of a pitch or resin is the degree of
temperature necessary to maintain it in a molten state,
and the brittle point is the degree of temperature neces-
sary to cause it to harden into a brittle state, which
state can be noted by striking it with a hammer.

Almost all of the different pitches have a different
melting point, and one that softens while in combination
with paint materials during exposure to atmospheric
temperatures, and will correspondingly harden to a state
of brittleness when the temperature lowers is sure to
crawl and crack on the surface. These cracks form in
transverse directions, forming a defective surface, which
is known as being " alligatored," resembling in shape the

32

peculiar formations on the surface of an alligator skin.

When an " alligatored " surface forms and continued
contraction and expansion of the metal ensues the edges
of the alligatored scales will finally curl up, " letting go "
of the metal entirely, thus allowing moisture and dust to
get underneath them, facilitating the process of ridding
the surface of the paint and promoting active rust forma-
tions.

The melting point of a pitch or resin may easily be
ascertained by placing the same in a small iron cup, into
which the bulb of a thermometer has been inserted, and
noting the results after heat has been applied to the
bottom of the cup.

Most of us know, however, that 'atmospheric heat on
a warm day will soften coal tar pitch to such an extent
that it will run on a surface or may be pulled out into
long strings and after cooling it by dipping it into a basin
of cold water it will fly into small pieces or may be
finely pulverized by a simple blow from a hammer. This
once soft and afterward brittle condition will be noticed
where paints or varnishes containing these pitches are
exposed on a surface at atmospheric temperatures, pro-
vided, however, that the same has been applied on the
surface heavy enough to obtain from them their maxi-
mum amount of wear.

In proportion to its bulk it requires a large amount
of volatile oil to reduce a resin, tar or pitch to a liquid
condition thin enough to be capable of proper spreading
properties, with a paint brush, at a temperature of 60
degrees F. Hence a very thin deposit of the solid base
of the mixture will be left upon the surface after the
volatile oil has evaporated. If extreme care is not taken
in brushing it on thick enough to allow for the evapora-
tion of the volatile oil and leave a substantial coating,
lack of durability will be inevitable, for the coating
which will remain on 'the surface will be so thin or
badly disintegrated by the solvent action of the oil first.
and its evaporation afterwards, that its adhesion to the
surface will be a matter of only a few months, or even
weeks, when subjected to atmospheric exposure, and
soon afterwards no trace of it is liable to be seen what-
ever. On the other hand, should it be spread on too
thick, a badly alligatored surface will result These are
the reasons why tar and asphaltum varnishes are so un-
reliable on tin roofs, and the author knows of no way

33

in which they may be made reliable in a practicable way
so that any one who knows how to spread paint can have
some sort of definite assurance that it is going to last
two years at least For, as explained, the thickness of
the coating has considerable to do with it, and as the
volatile oil evaporates so quickly, and indefinately in
varying temperatures, lack of uniformity of the deposit
left upon the surface is sure to ensue. In fact, the author
knows of hundreds of instances where a tar varnish
applied to a tin roof would last four years, and be alli-
gatored, and part of the same varnish taken from the
same barrel and applied by the same painter the follow-
ing day on an adjoining roof of the same conditions of
surface would dry out and wash off within a year. More-
over, weather conditions and temperatures render the
prevention of these defects of a highly volatile varnish
impossible.

Rosin more readily impairs the stability of a coating
into which it has entered than any of the other resins,
and every ounce of it combined with a gallon of paint
can be noticed to detract from its wearing qualities.

Many of the so-called paint dryers on the market are
nothing more or less than a thin rosin varnish, and in
consequence should be avoided. If, however, a dryer is
absolutely needed, only oil dryers with thickening or
oxygen absorbing properties should be used, and then
only in minimum quantities, necessary to meet unavoid-
able requirements.

34

Chapter VI.

Diagnosing Conditions of Exposure.

This is an important matter in the selection of the
most suitable paint for a purpose.

Plate II shows a smokestack below the roof in a sheet

Plate II.

mill. The paint was made by one of the most reputable
manufacturers in the country, and was compounded of

35

high-grade raw materials. The manufacturer guaranteed
it to last one year on this stack, which did not get over
700 degrees F. The condition of the paint, as shown in
the illustration, became so one week after it was applied
and thoroughly dry. Paint taken from the same mix in
the barrel was applied on a tin roof in the neighborhood
the same day, and five years afterward was in perfect
condition, -thus illustrating the proper use for that par-
ticular kind of paint. On the other hand, a cheaper and
differently made paint was applied to this stack a few
days later, after the scales were cleaned off, and it stood
the exposure fairly well for one year, and on a tin roof
in the neighborhood it did not preserve the metal over
four months.

Samples, which are occasionally painted on small
pieces of tin and sent out by the manufacturers to bend
and twist, appear all right until they have been exposed
to the weather for a year or so at which time their beau-
tiful appearance and preserving qualities have quite van-
ished.

In order to select a protective coating to the best pos-
sible advantage the conditions of exposure should be thor-
oughly understood first ; other conditions, such as the
character of the surface, and number of coats to apply
should follow.

The exposure of dry paint surfaces may be conveni-
ently divided into eight classes as follows:

1. Ordinary interior exposures.

2. Ordinary exterior exposures.

3. Extraordinary interior exposures.

4. Extraordinary exterior exposures.

5. Extraordinary exposure to heat (other than atmos-
pheric).

6. Extraordinary exposure to cold (other than atmos-
pheric).

7. Extraordinary exposure to liquids (other than at-
mospheric) .

8. Extraordinary exposure to abrasion (other than at-
mospheric).

No. 1. Ordinary interior exposure rarely covers a va-
riation of temperature of more than 60 degrees F., conse-
quently the expansion and contraction of the surface met
with in this class of exposure is so small that it has very
little effect upon an ordinary paint properly put on and
of good materials, neither does moisture and its rapid

36

evaporation prevail, so that here we have a condition
notable for its simplicity. Take, for instance, several
small sheets of tin or iron with clean, bright, dry sur-
face, coat them with coal tar varnish, asphaltum var-
nish, or, in fact, any cheap paint, and when thoroughly
dry lay them aside in the drawer of a writing desk ; 20
years later they will be in as good condition as the day
they were stored away. The sheets of metal, even with-
out paint, laid away, in like manner for the same length
of time, will also be found to be in excellent condition.
Structural iron work imbedded in cement or concrete or
otherwise incased should have one coat of paint applied
at the shop and two coats afterward, for the reason that
subsequent coats cannot be applied after the building is
completed, and once painted it is expected to remain so
as long as the building lasts. Cement and concrete, more-
over, are more or less porous and draw dampness to the
metal.

No. 2. Ordinary exterior exposure meets with climatic
conditions varying over 125 degrees F., ranging from the
chilly blasts of cold weather to the scorching rays of the
sun. Here expansion and contraction holds full sway,
tugging and straining at the adhesive and elastic prop-
erties of the paint while adhering to a surface not suc-
ceptible to paint absorption.

Hail, snow and ice, thawing and freezing, rain and its
evaporation attack vigorously the organic properties of
the vehicle in a paint. When a varnish is used to with-
stand this class of exposure the heat from the sun con-
tinues to liberate what volatile matter it contains until
it becomes baked so hard and brittle that its adhesive-
ness subsequently becomes a matter of only " here and
there." If the varnish is a thick coating it is sure to be-
come alligatored when the metal expands and contracts
while in the hard condition, and if it is a thin coating
it will become reduced to powder and wash off. This
sort of exposure requires a paint of superior, elastic, ad-
hesive, oxygen and water resisting properties, and as the
top coat is the one subject the most of all to these condi-
tions it should of necessity be made of carefully treated
linseed oil, .graphite and a suitable soluble solid composi-
tion to protect the oil so as to add permanence to the
vehicle as explained. The reason for using graphite for
the pigment is explained on page 22.

The class of steel work generally coming under this

37

class of exposure is bridges, ornamental ironwork, fences,
fire escapes, gutters, valleys, spouting, roofing, siding,
towers, sheathing and shutters, &c. New materials of this
class should receive at least one coat of paint at the works
and one coat after it is put up.

No. 3. Extraordinary interior exposure, such as will
be met in damp cellars, livery stable roofs (exposed on
the under side to ammonia fumes), cast house roofs at
furnace and foundries subjected to steam and heat, under
side of roofs of steel mills directly over sulphuric acid,
pickling vats, pulp mills, paper mills and ships' holds
which sweat continuously, &c., have considerable effect
upon the paint on the surface and paint thus exposed
should dry harder and have more soluble solid in its com-
position than class No. 2 : two good coats of the most
suitable paint for this class of work are in most cases
most satisfactory, and when the top coat loses its effi-
ciency it should be replaced with another one before ac-
cess to the metal is gained, as this will save considerable
labor in removing rust which would otherwise form.

No. 4. Extraordinary exterior exposure are those ex-
posures where the atmosphere is surcharged with acid
fumes, which generally emanate from open coke ovens,
chimneys, locomotive stacks and chemical works, &c. The
effects of this class of exposure varies extensively, a
great deal depending on the distance from where the
fumes emanate and the character of them. Painted metal
work of all kinds, especially roofs and bridges, in the
vicinity of these quickly lose their protective coating if
the paint is not made of the proper materials to with-
stand the exposure. Like class No. 2, this exposure
necessitates the use of a protective coating capable of
withstanding considerable expansion and contraction, and
should not harden so much as the paint needed for class
No. 3. It must furthermore have a vehicle protected by a
soluble solid composition properly prepared to stand the
surcharged atmosphere ; and an inert pigment, such as
graphite, white lead and red lead pigments, especially are
to be avoided in this class. If this form of exposure is
very severe three coats of paint should be used on the
metal work.

No. 5. Extraordinary exposure to heat takes in those
conditions where heat is produced by artificial means
greater than atmospheric heat, and comes into direct
contact with the painted surface. This heat may come

38

in contact with paint exposed to outside atmospheres, or
it may come in contact with paint exposed to inside at-
mospheres. The class of materials subject to the former
consists of smokestacks, blast furnace stoves and locomo-
tive front ends, &c., and those subject to the latter con-
sists of boiler fronts, furnace fronts and hot air and
steam pipes. In all cases corning under this class the
maximum amount of temperature should be ascertained,

Plate III.

and if found to be more than the boiling point of water
(212 degrees F.) a compound vehicle will be necessary.
As explained on page 21, ordinary pigments, such as
graphite, Venetian red, yellow ochre, or umber, are prac-
tically fireproof, consequently the fact remains that the
heat resisting properties of a paint is equal to the amount
ot" heat which the vehicle will stand. Should the heat run

39

•>.-' IKE

4<VERSITY

over 600 degrees F. little or no linseed oil should be used,
and a soluble solid composition of a melting point a few
degrees higher than the hot surface must necessarily be
expected to be used for any permanence in this respect.

In 1902 officials of The American Sheet Steel Com-
pany called upon the author to make several tests per-
sonally on the hot smoke stacks over their pair furnaces
and slab mills, stating that the paint when selected and
bought would have to be applied to the stacks while hot.
for the reason that the furnaces were always going and
the fires could not be put out without too much expense
and inconvenience.

Twenty-two different kinds of paints were tested in
this manner, no two showing similar results. The author
rather than allow anyone else to prepare the surface
for the test and not do it thoroughly, did so himself, so
that the experience thus gained would be of subsequent
value. Plate III shows the author scraping the hottest
portion of the stack which was to be tested. This opera-
tion was followed by the painter.

Flames were bursting forth from the tops of the
first, second, third and fifth stacks, and the roofs were
so hot that the soles of the shoes were scorched, and
those making the test were compelled to keep moving.
Vapor can be seen coming from the wet paint on the
second stack, and the paint brush had to be moved fast
in order to keep the bristles from burning. The scraping
tools became so hot from induction that they were
handled with difficulty.

Plate IV shows the tools that were available for
cleaning at the time, and Plate V shows rust scales and
old paint scales (one-quarter the diameter) removed.

Red heat of steel or iron is over 900 degrees F. and the
author knows of no vehicle that wrill stand this heat and
be water proof and rust preventing at the same time.

Whitewash or calcimine, sometimes called water
paints, and sodium silicate used as a vehicle, will stand
much more than 900 degrees F., but paints made of these
will not stand water or moisture, nor will they stick to
the surface long after being thoroughly hardened. Only
one coat of paint is recommended by the author for this
class of work, for the reason that extremely hot sur-
faces usually burn off the paint prematurely, in which
case frequent applications are necessary, and two coats
would be a considerable expense in so doing. It would

40

be folly, however, to expect to keep paint in a good con-
dition for more than a few months on a surface as hot
as 900 degrees F. The nearest material approaching a
protective coating to stand. over 900 degrees F. would be
a coating of porcelain enamel. This would take more heat
than 2000 degrees F. to melt it on the surface, and for

Plate IV.

this reason it would be an expensive and impractical
operation, possible only on new work while in the factory
preparatory to erection. f

An approximate estimate of temperatures on a metal
surface may 'be had toy applying liquids of known boiling
points on the surface and noting if they 'boil.

No. 6. Extraordinary exposure to cold generally takes

iii conditions such as cold storage plants having steel con-
struction within, the inside surface of steel plates com-
posing ships bottoms, the outside surface of standpipes
or water cylinders of hydraulic pumps, &c. The varia-
tions of temperature on these surfaces are slight or are
below the amount necessary to injure a paint for the rea-

Plate V.

son that they rarely if ever reach higher than TO degrees
F. The greatest amount of injury which these conditions
inflict to a paint is due to chilled vapor resulting from
a damp atmosphere condensing on the surface resembling
sweat. Should the conditions be such that this sweat
reappears soon after it has been removed, preventing the
maintenance of a dry surface long enough to apply the

42

paint and enable it to become dry, the painting should 'be
deferred until the proper condition can be met with and
then paint that will dry and harden quickly should be
used. This will necessitate the use of a paint which has
very little or no oxidizing oil.

A volatile solvent varnish vehicle paint containing
graphite for a pigment and a soluble solid known to the
author as Nicaragua gum. has been found to foe the 'best
for this class of work. This kind of paint hardens so
thoroughly and so quickly that it would not stand such
exposures as class No. 2 with any degree of certainty
or satisfaction, and therefore should only 'be used for ex-
posures of this class.

No. 7. Extraordinary exposures to liquids takes in a
class where water is maintained in direct contact with the
paint, such as ships 'bottoms, steel intake cribs, tanks,
standpipes and portions of gas storage tanks commonly
called gas holders. These require a compound vehicle
paint with very little oil, or a varnish paint similar to
that used for class No. 6, but should be heavier bodied
and contain less volatile solvent, so that a heavy coat-
ing of the basic material will remain on the surface.
This is necessary to withstand the extreme aqueous pres-
sure against the paint film.

No. 8. Extraordinary exposure to abrasion takes in a
class where friction eliminates a paint from a surface be-
fore it gets a chance to demonstrate its preserving proper-
ties by virtue of exposure to atmosphere, heat, gases or
water, such as coal bunkers, ships' holds, freight cars and
metallic shields underneath the flooring of bridges under
which locomotives pass emitting carbonaceous grit from
the smokestacks.

This class of paint should be slightly harder than that
used for exposure No. 2, but not hard enough to become
cracked or broken by violent blows, such as that of coal
being loaded into cars and striking the surface of the
car. It should have graphite exclusively for a pigment.
This paint when almost dry should be dusted with the
best quality of slippery dry graphite, then allowed to
dry and then polished with a woolen swab or sheep skins
with the wool on (using the wooly side). The finished
surface will then have a highly glazed surface that will
withstand more mechanical abrasion than any othei- form
of paint coating which the author knows of.

43

Chapter VII.

The Selection of the Most Suitable Preservative.

The selection of the most suitable material should be
governed not only by the class of exposure to be met

Plate VI.

with, but also the number of coats of paint to be used
and the time allowed for it to dry properly.

Plate VI shows two samples selected from several

44

hundred of which the author has been giving: thorough
time tests. These samples were exposed in the Pitts-
burgh District, where the atmosphere is surcharged with
sulphuretted hydrogen, carbon dioxide and sulphur fumes,
&e. The paint was applied on bright, smooth sheets of

Plate VII.

steel. No. IV shows an improperly prepared graphite
paint and No. VII shows a properly prepared graphite
paint.

One shows that before the end of four years the
protective qualities of the paint were exhausted and the
steel to be badly eaten with rust. The other shows that

45

the protective qualities of the paint were not impaired
during the same length of time, the metal remaining as
bright underneath the coating of paint as the day it was
applied.

No. IV was taken from the regular stock paint of " a
get rich quick " paint concern and was advertised as
" their best grade " and the " best paint in the world."

No. VII was manufactured by a concern who does not
make bombastic claims for their products, but depend
upon their reputation for their continuance in business.

An enormous spreading capacity of a paint is often a
misleading, fradulent or deceptive proposition offered to
purchasers of paint in order to secure their patronage.
The spreading capacity of almost any paint of good body
may be increased by thinning it considerably with a
volatile or a drying oil, and this decreases the cost per
gallon by reason of the increased bulk resulting from
its extension by the use of a cheaper thinning material
than the cost of the paint. Therefore claims for supe-
riority of a paint due to its superior spreading capacity
should not necessarily add anything to the value to a
statement of this sort. Furthermore, the less spreading
capacity a paint has the more body it possesses. This
body is generally the most costly part of a paint, and
the fact that it is too heavy or thick to possess spreading
qualities equal to a thinner paint should not detract from
its value after taking into consideration the cost of the
thinners necessary to reduce the body and increase the
quantity and spreading capacity to the extent most de-
sired.

A basis whereby deductions may be made to approxi-
mate the average thickness of a coat of paint on a smooth
flat surface, which does not absorb any of the paint, may
be readily calculated in the following manner :

A legal standard United States gallon we know must
contain 231 cu. in., and if 1 gal. of paint is spread over
a surface containing 231 sq. ft., the wet paint will average
1-144 in. thick.

In like manner should the paint be spread twice as
far and cover 462 square feet to the gallon it would be
1-288 in. which thickness can be compared to the thick-
ness of the leaves of a book having 288 pages to the inch.
Now when the paint is dry it will either thicken or be-
come thinner — the former if a linseed oil paint and the

46

latter if a volatile oil varnish paint — therefore allow-
ances should be made accordingly.

The writer believes that a protective coating averag-
ing less than 1-144 in. thick is not sufficient protection
to a metal surface exposed to any class of exposure in-
tended for long service and that 1-72 in. is not necessary
in any case where high grade material is used.

The spreading capacity of a paint should be averaged
when based upon a standard condition of surface the

1 GALLON
OF PAINT

1 SQUARE FOOT
144 SQUARE INCHES

most suitable for the purpose being bright clean tin
sheets or glass and estimates for other forms of surfaces
based upon variations from the standard. The spread-
ing capacity will also depend upon the temperature and
for convenience 70 degrees F. is recommended.

Careful and slovenly spreading of paint will cause
a great variation and lack uniformity of thickness of a
coating, nevertheless in any case the attainment of an
average estimate of thickness can not be depended upon.
When, however, a paint is advertised to cover 1000 sq.
ft. to the gallon it means necessarily that the coating
must average less than 1-576 of an inch thick which may
be compared to thin tissue paper.

47

Pigments may easily be tested for their fineness of
texture by simply rubbing them in a dry state between
the fingers or upon the palm of the hand, and if the
pigment is mixed in a drying oil it can be separated out
and dried by thinning the paint with gasoline, vigorously
shaking together the mixture allowing the pigment to
settle to the bottom, and washing out the heavy oil, then
pouring off the liquid, repeating the operation until all
of the drying oils have been extracted, after which the
pigment may be dumped out upon a sheet of blotting
paper and allowed to dry.

It will be noticed that the best grades of graphite
" rub up " into a higher gloss between the fingers than
any other known paint pigment and that when this pig-
ment does not " rub up " into a slippery finish it is
adulterated.

Vehicles may be tested in a simple way for com-
mercial purposes by allowing the pigment to settle to
the bottom, pouring the vehicle upon a piece of glass, al-
lowing it to dry for 48 hours and then subjecting it to a
temperature of say 200 degrees F. (up near a hot stove)
for several hours, after which cool off by soaking it into
cold water for 30 minutes, wipe dry with a cloth vigor-
ously and see whether any of it will rub off, after which
take the blade of a pocket knife and cut into it with a
long steady cut beneath the paint and along the surface
of the glass. If the vehicle can be then cut leaving long
tough and elastic strips it can reasonably be expected
to possess good qualifications for ordinary exposures met
with. However for exposures such as 3, 4, 5, 0, 7 and S
they should in addition be given actual time tests to
the exact exposures to be met with, keeping detailed ac-
counts of the conditions and the kind, quality and
amount of raw materials used, so that the paints thus
prepared for use may be intelligently compared for future
selection.

Driers should be given the same test as the vehicle,
noting, however, the strength of the drying properties, by
the amount necessary for use with the vehicle and the
time consumed in the drying of the oils thus tested.

A paint oil or varnish is considered by the author
to be perfectly dry at such time when at a temperature
of 70 degrees F. it refuses to adhere to a sheet of writ-
ing paper smoothed over it and pressed down hard by
the palm of the hand. This condition at the very least

should prevail before additional coats of paint are ap-
plied.

However as much additional time as this condition
requires to consume should be given before the same is
attempted.

Volatile oils may be tested by allowing them to
evaporate from a sheet of glass and noting whether
there is a greasy deposit left on the surface, which if so,
shows a substance which when entering into the liquid
portion of a paint will seriously prevent the drying of
it and cause an endless amount of annoyance, sometimes
necessitating the removal of the paint entirely, which if
not done would prevent the proper adhesion of more
coats of paint.

A great deal more might be stated relative to the
testing of materials.

The writer has noticed that the signs of the times
show an increasing tendency unfortunately on the part
of the general property owner to leave the question of
maintenance and selection of materials to others. The
luxurious modes of entertainment now prevalent entice
the property-owner to more pleasant occupations during
the intervals of the rush of business than formerly, when
each property owner not only painted his own house
but made his own paint and made it to last.

49

Chapter VIII.

Deductions and Conclusions.

After pursuing the subject of rust prevention it be-
comes very apparent that many questions are involved
that do not clear the way, for those who cannot give it
much thought or attention.

It does not take much of either, however, to deduce
the following facts:

1. The property owner should be satisfied that the
surface to be protected is as clean, dry, smooth and firm
as it is possible to get it before his time, money or pa-
tience is expended thereon. Without this important con-
dition any means to be employed would only be wasted.
Inasmuch as the preparation of the surface, the employ-
ment of the proper kind of material and the quality of
work done, when undertaken by a contractor may easily
be manipulated by him in such a way that he may greatly
profit financially to the detriment of the owner, it is
recommended that the owner purchase his own material
direct and hire his men by the day to do the work. Even
should the men put in more time than necessary, the
chances are that the work will not have been slighted, and
that the total cost of the job would be much less than the
same quality of work and materials would be supplied by
the contractor.

2. The owner should purchase his paint in different
shades, using a different shade for each coat, so that the
detection of omissions in thoroughly covering the surface
may be readily accomplished. The paint should be deliv-
ered on the ground in sealed packages guaranteed by the
most responsible maker in whom the purchaser may have
confidence.

3. It should be contained in receptacles that will main-
tain it in a good condition, and enable it to be thor-
oughly mixed or agitated during the progress of the work,
so that the paint thus used is of a uniform consistency
until the work in hand is fully completed.

Rain, dust, sand, mortar, plaster or refuse from build-
ings close by have often found its way into the paint
barrel, rendering the contents unfit for use.

The great difference in the specific gravity between

50

pigment and vehicle causes the former to readily precipi-
tate to the bottom in a very short time, even in the very
best paints, and the best results can only be obtained by
energetically keeping the paint stirred up.

The great drawback to the ordinary paint barrel is
due to the fact that the head must be removed in order
to thoroughly agitate the contents by means of a board
or paddle.

To remove the head without destroying the barrel

(which cost generally over $1.50 each) two or three hoops
must be driven up to allow the staves to spread at the
top, so that the head can be disengaged from the chime.
When the staves spread in this manner openings are left
between them, allowing the paint to run out, entailing
waste and loss of time tightening up the barrel again.

Barrels containing various kinds of paint mixers
have frequently been tried, but almost always have

proven either complete failures, or so unreliable that de
pendence upon them results invariable in the abandon
ment of their use.

An ordinary barrel filled with good paint contains sev-
eral hundred pounds of pigment, which when settled to
the bottom becomes tough like putty.

The barrel paint mixers that have been tried becomes
imbedded in the pigment and stuck fast with as much
resistance apparently as would be experienced trying to-
turn a spade around when it is shoved down deeply in
firm soil.

• These drawbacks have led the writer into experiments
resulting in the construction of a barrel paint mixer
which is recommended to do the work.

The stem and crank as seen in the above illustration
(1A, 2A, 3A) is made of a one-piece malleable casting,
and the side arms or paddles are made of stiff spring
steel y8 in. thick. These side arms are connected by
means of loosely fitting rivets, and may be drawn up
edgewise through the pigment so as to fold up, thereby
reducing the diameter of the agitating surface, so that a
portion of the pigment may be moved and mixed with the
vehicle; after this is done the agitator paddles may be
spread out as required until the whole width may be used
for all of the pigment at one operation.

The mixer should be turned rapidly to the right for
8 or 10 revolutions, and then reversed quickly, this gen-
erates an undercurrent coming from the top in the form
of a whirlpool, and leaves nothing to be desired in the
matter of thorough agitation.

It is an important fact that the first coat of paint
usually applied by the manufacturers on newly made
metal work is of the cheapest variety, unless specifica-
tions and contracts to the contrary offset this result.

Every owner of. property containing metal work that
needs protection should thoroughly understand " what he
needs as a preservative, and demand that it be properly
applied by the painter."

Paint should be spread on a surface in temperatures
between 50 and 90 degrees F., and should be spread on
carefully that all air bubbles under the paint should be
eliminated.

The application of paint with a machine or spray
should not be encouraged, for the reason that air bub-
bles get under the fine spray and prevent the close ad-

52

herence of the paint to the surface, and also has a tend-
ency to aerate the paint. The first coat on metal should
not be quite as elastic as the succeeding coats. It should
dry hard, tough and slightly yielding. Its subsequent
hardening is somewhat prevented by the coat on top of it.

The last coat, or top coat, should dry slower than the
one underneath, so as to withstand the drying tendency
of the weather and meet expansion and contraction where
• it is mostly needed.

Black paints are the most opaque and should be used,
not only because the material out of which they can be
made affords the production of the best protective coat-
ing, but also for the reason that it presents a striking con-
trast to the color of rust or corrosion.

When red or brown paints are used the appearance
of rust can only be detected at times when close inspec-
tion is promoted, and this is very often deferred by over-
sight or neglect.

Too much importance cannot be attached to the neces-
sity of preserving metal before corrosion or oxidation
has taken place.

The loss that generally ensues when metal surfaces
are not continually protected in every corner and crevice
is rarely appreciated. The wasted metal resulting from
one moment's chemical action can never be replaced to
its former condition (commercially speaking), and the
section so effected is ofttimes so very difficult and costly
to replace, especially -in hidden structural work and
bridges, that these matters are in many cases postponed
until the whole structure becomes condemned as dan-
gerous and a new one needs to be built.

Care should be employed by the purchaser of new
structural work, bridges or sheet metal work, where the
protective coating is furnished by the contractor ; in see-
ing to the explicit and proper wording of the specifica-
tions so that the right brand, make and best paint ma-
terials are clearly defined so as to leave no valid chance
for substitution. This rule should always govern wher-
ever and whenever good paint is wanted. Specifications
for applying the paint should always state " the number
of coats wanted and that there should be no air holes,
moisture, oil, grease or dirt under the paint ; that it
should be well brushed on by hand to a thoroughly
cleaned and dry surface, thoroughly cover the said sur-
face and be applied in dry weather between temperatures

53

of 50 to 90 degrees F. (unless the paint is a special kind
and is shown by the purchaser to especially require dif-
ferent temperature for application").

This should never be left for engineers to do, for a
wide diversity of opinion exists as to what make or
brand should be used, even among those of many years'
experience.

Furthermore, engineers or architects very often re-
fuse to specify any particular make of paint, for obvious
reasons. It savors of partiality and leaves room for se-
vere criticism. On the other hand, if the contractor can
evade supplying an established brand of high grade ma-
terial and suit himself in the furnishing of paint made
of raw materials selected by himself, rendering it im-
possible for the engineer (without giving the material a
daily chemical analysis), to ascertain its true value he
has the chance to utilize the greater of the two evils to
his own profit.

In cases where the engineer will not consult with the
owner on the brand or make of paint to be used and spec-
ify the same in the contracts, the author suggests that
the specifications read as follows : " All paint and paint
materials used must be selected or approved by the
owners before the same is permitted to be used. It shall
be subject to the inspection and refusal of the engineer
when the same is not branded or recognized as such."
This would relieve the engineer of a responsibility which
is not necessary for him to be expected to shoulder.

No engineer, in designing a structure, can make effi-
cient allowance for decay, for the reason that the time,
place and extent of such action is an unknown quantity
and always will be.

Loss of life and property due to collapse resulting
from decay is a serious theme to reflect upon. Any ex-
isting doubt as to the necessity of giving the work a good
coat of good paint should be decided upon before it is
too late.

54

THIS BOOK IS DUE ON THE LAST DATE
STAMPED BELOW

AN INITIAL FINE OF 25 CENTS

WILL BE ASSESSED FOR FAILURE TO RETURN
THIS BOOK ON THE DATE DUE. THE PENALTY
WILL INCREASE TO SO CENTS ON THE FOURTH
DAY AND TO $1.OO ON THE SEVENTH DAY
OVERDUE.

APR

JUL 21 1939

LD 21-100m-8,'34