By Ellery C. Bartlett.
There is hardly any part of the world that has not been drawn upon for
suitable skins to be made into leather for bookbinding. The skins
generally used are goat, seal, pigskin, cowhide, calf, and sheep, and
they vary in quality according to the country they come from and the
manner in which the animals are cared for, the stall-fed animals, or
those that are protected from storm and have regular food, producing
the best skins.
In preparing these skins for bookbinders, great care has to be taken
to extract as much of the natural oil as possible, as this is apt to
discolor the gold leaf decorations put on by the artistic binder.
Tanners usually buy skins with the hair on. They are first put into
water, for the purpose of softening them, after which they are laid
over a beam and a knife is drawn over them, to still further soften
them. They are then put into vats containing slack lime-water, which
loosens the hair and kills the animal life remaining in the skin.
After having been in these vats for a period of about ten days, they
are washed in water, to remove the lime and clean the skin. Afterwards
they are put through a process called "bating," which destroys any
animal matter in the skins which may have escaped the first process,
and they are then finally cleansed by a solution of bran and water,
which also prepares them for tanning.
After the skins have been in tan for a week or more, they are taken
out, tacked on drying frames and all the wrinkles stretched out of
them. When thoroughly dry, they are ready for the coloring process.
After being colored, they are again tacked on the frames; and when
they are thoroughly dry again they are taken to the graining room,
where the finishing processes are done by skilled workmen, the utmost
care being needed to produce the desired result.
The matching of shades is a very difficult process, as the question of
color must be decided while the skins are still wet. Weather
conditions have a very important bearing on the manufacture of
leather, and changes in the atmosphere often spoil all the careful
work that has previously been put on a skin.
The finest leather for books comes from France, although a good
quality is made in England and Germany, and the United States is
rapidly improving its output.
The graining of the leather to bring out the natural grain in the
skin, is done by hand and sometimes by electroplate reproductions of
the natural grain by means of the embossing press. When large grain is
wanted, the skins are shaved only slightly on the back; if small
grains are wanted, the skins are shaved thinner. This process removes
all roughness from the back of the skin, leaving it smooth and clean.
Formerly the binder, in preparing his covers, was compelled to pare
the edges with a knife, which was a slow and laborious process; but
now--thanks to the inventive American talent--he can have the whole
skin split to any desired thickness or thinness, without injury; or,
he can have the edges pared by cleverly devised machinery.
Leather manufacturers are able, by using splitting machines, to split
skins so that both parts of a skin can be used--the upper part of the
skin being called the grain and the lower the flesh. Were this not the
case, it would be impossible for the binder to supply the needs of his
customers, as the output does not keep pace with the constantly
increasing demand. In fact, binders are constantly looking for
substitutes, but, after all, there is nothing so good as leather.