This illustration from Diderot’s great eighteenth-century French encyclopedia shows the essential operations in a tannery: A) washing hides in a stream; B) scraping hair or flesh from a hide on the “beam”; C) soaking hides in a series of lime pits; D) 동탄오피 bedding hides in a tanning vat with a layer of shredded bark between each hide; E) stirring lighter hides in a hot water tanning solution.

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Tanning brings about within the fibrous structure of a pelt certain chemical and physical rearrangements that are still imperfectly understood. Their effect, however, is to render the pelt permanently imputrescible, pliable when dry, and capable of sustaining repeated wetting without hurt. The agents responsible for the transformation, known as “tannins,” are found in almost all plants, in certain minerals, and in various readily oxidizing oils.