Tanning (leather)

Tanning is the process of treating skins and hides of animals to produce leather. A tannery is the place where the skins are processed. Tanning hide into leather involves a process which permanently alters the protein structure of skin, making it more durable and less susceptible to decomposition, and also possibly coloring it.

History

Tanning has been practiced for centuries by various cultures. The ancient Egyptians and Romans were known to have used vegetable tanning, a method that is still practiced today. The Middle Ages saw the introduction of alum tanning, which was faster than vegetable tanning but produced a less durable leather.

Process

The process of tanning involves several stages, including preparation, tanning, and crusting. Each of these stages involves different methods and materials.

Preparation

Preparation includes soaking, liming, and bating. Soaking helps to clean the hide and rehydrate it. Liming removes the hair and other unwanted material from the hide. Bating involves treating the hide with enzymes to soften it.

Tanning

Tanning can be performed with either vegetable or mineral methods. Vegetable tanning uses tannin, an acidic chemical compound from plant species. Mineral tanning, on the other hand, uses chemicals such as chromium salts.

Crusting

Crusting is a process that thins and lubricates leather. It often includes a coloring operation. Chemicals added during crusting must be fixed in place. Crusting culminates with a drying and softening operation, and may also include splitting, shaving, dyeing, whitening or other methods.

Environmental impact

Tanning has been considered as an environmentally unfriendly process due to the use of harmful chemicals and the waste produced. Many tanneries have been relocated to developing countries where environmental regulations are less strict. Improved methods, including vegetable tanning and chrome recycling, have made the tanning process less harmful to the environment.

See also

• Leather production processes
• History of hide materials
• Environmental impact of tanning

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