296 MODERN PAPER-MAKING
The prolonged soaking of coloured papers is not advisable, as the colours
are liable to fade.
Another drawback with reels which are allowed to stand and soak is the
fact that the deckle edges often stick together and cause tears at the edges of
the paper when being unwound at the dryer. To prevent this, the sides of the
reel must be washed with hot water, or a jet of steam should blow gently against
them during the unwinding.
The only point in favour of sizing and drying in two separate operations is
that the speed in the 'straight-through* method cannot be varied to suit varying
conditions of the atmosphere, and the slower the drying has to be done the
longer the soaking of the paper in the tub.
When the two operations are separate, the dryer can be slowed or quickened
at will, as the dryness of the paper demands, without interfering with the sizing.
Tub-Sizing with Feculose.—Feculose is sometimes used for tub-sizing writing
papers, either in combination with resin or with gelatine size. Provided that
the paper has not to be free from starch, excellent results may be obtained so
far as hardness and resistance to ink are concerned, if resin is also used, and
feculose is usually cheaper than the better grades of gelatine.
The method of preparing the solution is as follows:
200 Ib. of feculose are stirred up with 90 gallons of water, warm but not
above 160° F., and heated with steam injection until the temperature reaches
205° F. Allow to stand $ hour to ensure thorough cooking, then add 800 Ib.
(80 gallons) of cold water.
10 Ib. of resin size are placed in a tub and 8 gallons of water added, then
heated to dissolve the resin size with the addition of J Ib. of soda ash (the resin
size is used just as it is delivered); then add 2 pailfuls of feculose solution.
10 Ib. of alum are dissolved in 8 gallons of water with steam injection and
2 pailfuls of feculose solution are added.
The made-up resin size should now be added to the feculose solution through
a sieve and mixed well with a wooden paddle; next add the alum solution
and stir.
The feculose solution is now ready and should be about 5° to 6° Be. (8° to
9° Tw.}, but can be diluted to any desired strength.
By following this method the colloidal condition of the resin is obtained,
and therefore its maximum efficiency assured.
If the paper has been well sized in the beater, the resin and alum can be cut
out, but it is advisable to add i to i per cent of formalin calculated on dry
feculose to ensure the keeping qualities of the feculose solution. Where alum
is used the formalin is not required, as die alum prevents fermentation. For-
malin does not thicken feculose as it does glue.