The term hide is used to designate the skin of larger animals ( e.g., cowhide or horsehide), whereas �skin� refers to t.... tan leather

Although the skins of such diverse animals as ostrich, lizard, eel, and kangaroo have been used, the more common leathers come from seven main groups: cattle, including calf and ox; sheep and lamb; goat and kid; equine animals, including horse, mule, and zebra; buffalo; pig and hog; and such aquatic animals as seal, walrus, whale, and alligator. The modern commercial leather-making process involves three basic phases: preparation for tanning, tanning, and processing tanned leather. A hide will begin to decompose within hours of an animal's death; to prevent this from happening, the hide is cured by a dehydrating process that involves either air-drying, wet or dry salting, or pickling with acids and salts before being shipped to a tannery. The tanning process derives its name from tannin (tannic acid), the agent that displaces water from the interstices of the hide's protein fibres and cements these fibres together. The extracted material is processed into tanning liquors, an! d the hides are soaked in vats or drums of increasingly strong liquor until they are sufficiently tanned. Mineral tanning, which uses mineral salts, produces a soft, pliable leather and is the preferred method for producing most light leathers. In mineral tanning the hides are soaked in saline baths of increasing strength or in acidic baths in which chemical reactions deposit salts in the skin fibres. Oil tanning is an old method in which fish oil or other oil and fatty substances are stocked, or pounded, into dried hide until they have replaced the natural moisture of the original skin. Oil tanning is used principally to make chamois leather, a soft, porous leather that can be repeatedly wetted and dried without damage. After the basic tanning process is completed, the pelts are ready for processing, the final phase in leather produ The leather is then dried to about 14 percent moisture, either in the air or in a drying tunnel or by first stretching the leather and then ai! r or tunnel drying it. tan leather