leather

Material prepared from the hides and skins of animals, by tanning with vegetable tannins and chromium salts. Leather is a durable and water-resistant material, and is used for bags, shoes, clothing, and upholstery. There are three main stages in the process of converting animal skin into leather: cleaning, tanning, and dressing. Tanning is often a highly polluting process.

The skin, usually cattle hide, is dehydrated after removal to arrest decay. Soaking is necessary before tanning in order to replace the lost water with something that will bind the fibres together. The earliest practice, at least 7,000 years old, was to pound grease into the skin. In about 400 BC the Egyptians began to use vegetable extracts containing tannic acid, a method adopted in medieval Europe. Chemical tanning using mineral salts was introduced in the late 19th century.