The goat (Genus Capra) finds most favour as furnishing a suitable skin among binders. This animal, in the proper sense of the word “goat” exclusive, belongs to the Old World, being confined to the area north of the southern flanks of the Himalaya, though one species is found in Egypt and another in Abyssinia, but quite unknown in the remainder of Africa. In America the term “goat” is applied to our ruminant. While being essentially a mountain animal, goat breeding has become a business to-day throughout the world, which has been laid under contribution to supply the enormous demand which has been created during the past twenty years by the chrome glacé kid manufacturers, one maker alone requiring 5,000 dozen skins per diem to keep his factory running full. The skins generally employed for book purposes are the European and Northern African supplies, though many other sources are equally suitable. Goat skins, on account of their firm nature are best tanned in pure sumach (Sicilian). Time has conclusively proved this point. In the Rylands Library in Manchester (Eng.) are two heavy volumes bound in plain undyed sumach-tanned goat-skins which were bound in Spain in the 16th century, and are to-day in a perfect state of preservation. The Niger skins (mixed goat and sheep) which have found favour among certain bookbinders are produced from a breed of Egyptian goats, tanned and prepared by Nigerian natives with a species of nut-galls which gives them that peculiar close, tight feel, and when such firmness is required in European stock it may be equally effectively produced with oak bark. The large proportion of so-called moroccos offered to-day are made from skins tanned in East India with a catechol tannin. It is unfortunate that this tannage has failed to withstand the tests supplied by the Scientific Committee appointed by the Society of Arts on Bookbinding Leathers, because it excludes from the Binding Trade a very useful and cheap supply of pretty looking and feeling skin ready to hand for finishing in moroccos. While condemned for permanent library work—that is, guaranteed leathers—the writer sees no reason why such leathers may not safely be used for Lending Library work, where the life of a binding is not expected to run more than ten years, provided the surplus tan is washed out and replaced by some nourishing material (fat), and in all processes inorganic acids and alkalis are avoided. Goat-skins differ from other animals mainly in the pronounced grain formations, while the texture of the skin is closer and firmer than a sheep, the grain is harder, more scale like, the papillæ between which the hair-holes are situate are most marked, and it is their formation which produces during the operation of “boarding” the grained morocco with its beautiful nodules. If these nodules or grains are bold and large it indicates a thick skin originally. Such grains cannot be expected upon a thin skin—it implies either over-reduction (shaving) in substance or embossing. Thin skins will produce a small shortlike grain. If the grain is fine on a large skin it may have been reduced too much in substance, and thereby loses most of its muscular structure and strength. It is necessary when buying moroccos, which are not only expensive but are expected to yield longevity and be hard wearing, to obtain a manufacturer’s guarantee that the skins are genuine goat (Genus Capra) and not mountain sheep (Argali) or bastards, and that they have been prepared in accordance with the Society of Arts’ Report on Bookbinding. In value the moroccos vary considerably in price, according to substance, size, quality, and character. The skins are generally bought in the dry pelt state with hair on at per lb., the large, plump, well-flayed skins commanding higher prices than less favoured ones. In this state it is difficult to detect grain faults, consequently to the manufacturer it is somewhat of a speculation, and unless he is well informed in his trade he stands to lose heavily. Generally speaking the prime clear grains go into bright colours at higher prices than defective grains, which can be hidden by darker colour with the aid of a suitable finish. For example, the colour of the Niger skins previously referred to is an excellent one for hiding grain defects. The amount of absolutely perfect skins is small, but the remainder are good skins in their class for half-bound work. The perfect skins will realise up to 2s. 6d. per square foot, and according to quality and colour the balance will range down to 8d. per square foot.
Calf skins have long been favoured for bookbinding, but through much variety of tannages and faulty selection of skins have been brought somewhat into disrepute for permanent work, but if prepared by slow tanning in oak bark or sumach there is no reason why they should not be reinstated. Undoubtedly the calf is favoured by Nature with the finest and silkiest grains of all animals, and though too tender for rough usage, is nevertheless, if suitably nourished, capable of standing greater wear than it is credited with. Calf skins for bookbinding are the product of the domestic ox (Bos taurus), and as this useful animal is bred the world over, we are not wanting in supplies, nor is one land more favoured than another. If the principle is accepted that small books require small thin skins, as the books increase in size so should the skins and substance, a great difficulty will be overcome, because in buying calf one of the fatal mistakes made is the stipulation that large skins must be thin. If this is insisted upon they must be split or shaved of all their muscular tissue till merely the grain or skiver is left. A reasonable amount of shaving is permissible, but splitting is disastrous. Calf skins are invariably free from grain faults, so that for delicate shades of colour they are particularly suitable. The grain does not lend itself to any very definite formation in boarding (graining), therefore calf by preference should be left smooth. In the raw state they are purchased by the pound, and such cost being a governing factor in selling, the price when finished may vary from 8d. to 1s. 8d. per square foot.
The skins of seal (family Phocidæ) are most useful for bookbinding, possessing special features, viz.: evenness of quality throughout, there being no flanky or abdominal parts, extremely durable and producing pretty grains either coarse or fine, dependent upon the substance and character of the skins. The sources of supply are Russia, Norway, Spitzbergen, Greenland, Labrador, and Newfoundland, the largest supply coming from the latter place. Isolated supplies have been shipped from the Falkland Islands and Antarctic. These are the true or earless seals (family Phocidæ), commonly called hair seals in contradistinction to the fur or eared seal (family Otaridæ) which inhabit the Pacifics. As a leather for bookwork when tanned with a pyrogallol tannage it is soft and kind to the touch, having few equals and no superiors. It is essentially a hard-wearing leather and in this respect only equalled by certain classes of goat-skins and pig or hog skins. The “grained” skins exhibit a grain which sparkles in a manner which is peculiarly characteristic and absent in other grained leathers. The value of seal-skins, finished, ranges from 10d. to 2s. per square foot. The former are useful for half-bound books.
Finally, pig or hog skins have played an important part in ancient bindings of all sizes, and proved their great value as a hard wearing cover by coming down to us in a remarkable state of preservation, even on very heavy tomes. But, regretfully, some discredit has been cast upon this splendid skin, partly due to ignorance in manufacture, also to the very clever imitations. It is, perhaps, one of the easiest skins to reproduce in its grain features and solid character, though the imitations are easily detected by immersing a piece of the suspected leather in water until saturated, then pulling it out with the hands to stretch when the grain, which is produced by embossing, will disappear, while the true hog grain will remain showing clear hair holes through from grain to flesh. A hog-skin may be said to be practically fibreless, approaching nearer to a piece of tough gristle than anything else. In the raw state the skins are shipped from southern Europe, Danubian and Balkan States, China and the East generally, while North America has an almost unlimited supply, but Scotland produces the finest and most esteemed. In size they vary considerably, like all skin supplies, but a most useful skin for binders’ use will contain about 11 to 12 square feet. Slow oak-bark tanning is most suitable for this class of skin. Sumach may with advantage be employed after tanning to prepare them for the “dressing” or “finishing” process, but no mechanical or chemical means should be employed to overcome a too gristly nature, otherwise its unique capacity to withstand the act of attrition is proportionately decreased, or if some similar means are adopted to attain evenness of shade in dyeing, the same result may be expected: therefore, so far as it is practicable, this skin should be used in its natural state, if full durability is required.
Pigskins containing 11 to 12 square feet may be purchased, according to their quality and degree of manufacture, from 8d. to 1s. 4d. per square foot.