Tanning


17
Mar 10

How Is Leather Actually Made For Your Chair?

The black leather chair has always imposed the impression of status wealth and power, but is it really that, or is there a darker side to this well known piece of furniture? Join me on a journey and discovery into just what processes are involved in the production of leather and leather goods. And what these processes really cost.

It's the harsh truth that animals are processed daily, every day thousands of animals enter the meat production industry, these animals are processed and their skins or hides are shipped to various tanneries for processing. Most of these being cattle hide. Leather is the end result of animal hides, the only difference between leather and fur is leather is a by-product of the meat production industry, where the animal is slaughtered for consumption. Whereas with fur, the skin or coat is most desired the meat is the by-product and of little importance.

This skin, now known as a hide will on arrival at the tannery enter the pre-tanning stage. This is the first of three stages it will undergo before being classed as cured leather. The pre-tanning stages and tanning procedures are determined by the end product or market that the leather is intended for. The pre tanning process for most common leathers include, preservation, soaking, de-hairing, liming and de-liming

The hide is then ready for the tanning process. Most commercially available leather is tanned using a method known as chrome-tanning. As the name suggests the compound Chromium is used throughout the tanning process. The purpose of tanning is to change the proteins found in hide or skin into a stable and durable material, thus properly tanned leather will not putrefy when exposed to water. Hides undergoing Chromium tanning are loaded into a rotating drum and are submerged in a tanning liquor solution until soaked through. After which the pH of the solution is increased, this process is called basification. This fixes the tanning material to the leather, the greater the amount of adhesion results in a more stable end product with reduced shrinkage properties.

The wet leather is now removed from the drum and will have a bluish hue, it now passes into the third stage known as the crusting stage, where it may be split or thinned before being re-tanned, then dyed, dried and softened. The end result is a hide of leather softened and ready to be for fabrication. To make up a black leather chair could take up to three such hides. Depending on the style and size of the chair.


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