Leather is a material that is renowned for its durability and flexibility. These features make it suitable for the manufacture of many different products. It is most commonly used in the manufacturing of shoes, bags, wallets, clothes and furniture. There are many different types of leather, but the production process remains fairly standard.
How is leather made?
All natural leather is made from the hide and skin of animals. Commonly, leather comes from the hide of cows, but many other animal leathers are now available. Depending on the type of leather there are 3-4 stages of production; preparation of the hide/skin, tanning, crusting and coating.
When the animal hide arrives at the factory it is in its raw state and there are many undesirable components of the hide/skin to be removed. This may consist of removing the hair, soaking with water, removing extra flesh and fat, degreasing, bleaching and preserving.
Tanning is when the proteins of the hide/skin are converted and stabilized so they do not become putrid. There are many different methods of tanning, but the most common is to use chromium salts (known in the industry as “wet blue”) to stabilize the leather. The hides are loaded into a rotating drum with the tanning liquid and it slowly soaks into the hide. Once it has done this the pH is raised with sodium bicarbonate to activate the chromium’s ability to stabilize the protein.
The crusting process is often the last process in the production of leather. The skin/hide is thinned, retanned and lubricated. It may also be colored and softened before it is finally dried.
Some leather is finished with a surface coating. This can be applied a variety of ways including spraying, oiling or brushing.