Cowhide
Cowhide, sometimes known as American russia, is a leather which has increased enormously in use in the last twenty-five years. It is a thick, coarse leather, rather unattractive in appearance, strong when new, but with age rapidly deteriorating in quality, even when no deleterious substance has been used in tanning or dyeing. It is a harder leather to work than roan, but the quality is much more uniform and it can be used advantageously for binding fiction and other books which will be much used. In its natural state (undyed) it can be used in place of law-sheep for law books, but has a tendency to become dark. It can be obtained in many colors. Since it is too thick a leather to be used in full thickness, practically all skins are split, and the amount of flesh left with the grain determines the weight of the leather. A greater or less amount is taken off according to the purpose for which the leather is intended. Bookbinding cowhide costing 20c to 25c. a square foot is the lightest weight leather that has the right to be called cow.[4] The life of cowhide is from five to twelve years.
Buffing. Buffing is practically only the grain of cowskin from which almost all the flesh has been split. It is not suitable for library books, since it is very thin and begins to disintegrate in less than five years. After it is on the volume it is hard to detect, so that some library binders have been tempted to use it instead of cow. But as buffing is never sold as cow, the library binder has no excuse for keeping it in stock.
[4] This is the normal price of cow. The European war has had the disastrous effect of raising the price and lowering the quality. Until conditions become normal again all cowhide should be shunned.
Pigskin is one of the strongest leathers, having a hard, resisting surface and a good, tough fibre. In the grain, the holes which were left when bristles were removed are plainly visible, giving the leather a distinctive appearance, which can be imitated successfully, but which is much less often imitated than the grain of morocco. If there be doubt of the genuineness of pig, soak a piece of the leather until it has absorbed a quantity of water, and then stretch it. If the grain pulls out, it is imitation; if genuine, the bristle holes still show plainly. Oak bark tanning is the best for this leather, and, since it is more nearly gristle (less fibrous) than other leathers, dyes and chemicals should not be used which will interfere with its quality of resisting friction. It should be used in its natural color whenever possible.
Pigskin frequently comes in skins which are too thick for the binder to work easily, or which are very uneven in thickness. In such cases the paring down of the skin is likely to injure its strength. Because of its thickness pig is generally supposed to be more suitable for large than for small books, but inasmuch as several binders have used it successfully for years on small books, it may be taken for granted that it can be used with good results on all books, large or small, which are to receive hard usage. It needs constant handling, and the absorption of a certain amount of oil from the hands to keep it pliable. Otherwise it dries rapidly and cracks along the joint. This, however, is true of all leathers to a greater or less extent. Pig costs from 40c. to 45c. a square foot.
Goat
The leather which makes the strongest and most attractive binding comes from the skins of goats and is called morocco, because it originally came from that country. In the course of time goat skins from other countries were tanned with sumac (originally a distinguishing characteristic of a genuine morocco), but the same name was applied so that we now have the paradoxical terms, Turkey morocco, Levant morocco, etc. Moroccos have a beautiful grain, are flexible, soft and pliable to the hand, and resist hard wear; qualities which contribute to their great popularity.
Morocco varies greatly in quality as well as in appearance. Unfortunately the skins which are best in quality, considering the length of time they will wear, are not always those best in appearance. The skins of goats with long hair from the colder countries make beautiful bindings; but the skins of goats from the hot countries, such as the interior of Africa, having short hair, while not so attractive in appearance, are tougher and wear longer. In addition to the many grades of genuine morocco there are as many more imitations of it made from sheepskin, cowhide, etc. Only the expert can detect some of them in the skin, and even he may be deceived when the leather is on the back of the book.