Sheepskin.—A properly tanned sheepskin makes a very durable, though rather soft and woolly, leather. Much of the bookbinding leather now made from sheepskin is quite worthless. Bookbinders should refuse to have anything to do with any leather that has been artificially grained, as the process is apt to be highly injurious to the skin.
Pigskin.—Pigskin is a thoroughly good leather naturally, and very strong, especially the alumed skins; but many of the dyed pigskins are found to be improperly tanned and dyed, and worthless for bookbinding.
Sealskin is highly recommended by one eminent librarian, but I have not yet had any experience of its use for bookbinding.
The leather that I have found most useful is the Niger goatskin, brought from Africa by the Royal Niger Company; it is a very beautiful colour and texture, and has stood all the tests tried, without serious deterioration. The difficulty with this leather is that, being a native production, it is somewhat carelessly prepared, and is much spoiled by flaws and stains on the surface, and many skins are quite worthless. It is to be hoped that before long some of the manufacturers interested will produce skins as good in quality and colour as the best Niger morocco, and with fewer flaws.
Much leather is ruined in order to obtain an absolutely even colour. A slight unevenness of colours is very pleasing, and should rather be encouraged than objected to. That the want of interest in absolutely flat colours has been felt, is shown by the frequency with which the binders get rid of flat, even colours by sprinkling and marbling.
On this point I may quote from the committee: “The sprinkling of leather, either for the production of ‘sprinkled’ calf or ‘tree’ calf, with ferrous sulphate (green vitriol) must be most strongly condemned, as the iron combines with and destroys the tan in the leather, and free sulphuric acid is liberated, which is still more destructive. Iron acetate or lactate is somewhat less objectionable, but probably the same effects may be obtained with aniline colours without risk to the leather.”
CHAPTER XX
Paper—Pastes—Glue
PAPER
Paper may be made by hand or machinery, and either “laid” or “wove.” “Laid” papers are distinguished by wire marks, which are absent in “wove” paper.