A Dictionary of Arts: Tanning

A Dictionary of Arts, Manufactures, and Mines; containing A Clear Exposition of Their Principles and Practice

by Andrew Ure, M. D.;
F. R. S. M. G. S. Lond.: M. Acad. M. S. Philad.; S. PH. DOC. N. GERM. Ranow.; Mulh. Etc. Etc.

Illustrated with nearly fifteen hundred engravings on wood
Eleventh American, From The Last London Edition.
To which is appended, a Supplement of Recent Improvements to The Present Time.

New York: D Appleton & company, 200 Broadway. Philadelphia: George S. Appleton, 148 Chestnut St.
MDCCCXLVII

1847

TANNING (Tanner, Fr.; Gärberei, Germ.) is the art of converting skin into LEATHER, which see. It has been ascertained, beyond a doubt, that "the saturated infusions of astringent barks contain much less extractive matter, in proportion to their tannin, than the weak infusions; and when skin is quickly tanned (in the former), common experience shows that it produces leather less durable than leather slowly formed." The older tanners, who prided themselves on producing a substantial article, were so much impressed with the advantages of slowly impregnating skin with astringent matter, that they employed no concentrated infusion (ooze) in their pits, but stratified the skins with abundance of ground bark, and covered them with soft water, knowing that its active principles are very soluble, and that, by being gradually extracted, they would penetrate uniformly the whole of the animal fibres, instead of acting chiefly upon the surface, and making brittle leather, as the strong infusions never fail to do. In fact, 100 pounds of skin, quickly tanned in a strong infusion of bark, produce 137 of leather; while 100 pounds, slowly tanned in a weak infusion, produce only 117½. The additional 19½ pounds weight in the former case serve merely to swell the tanner's bill, while they deteriorate his leather, and cause it to contain much less of the textile animal solid. Leather thus highly charged with tannin is, moreover, so spongy as to allow moisture to pass readily through its pores, to the great discomfort and danger of persons who wear shoes made of it. That the saving of time, and the increase of product, are temptations strong enough to induce many modern tanners to steep their skins in a succession of strong infusions of bark, is sufficiently intelligible; but that any shoemaker should be so ignorant or so foolish as to proclaim that his leather is made by a process so injurious to its quality, is unaccountably stupid.