Leather: The Various Types Of Tanning

By

All leather is produced through some type of tanning process. What differs are the types of materials that are used to perform the 'tanning' function that turns animal hides into wearable leather. Below we'll discuss the various types of leather and how they are produced.

Vegetable tanned leather is produced using tannin. Tannin is vegetable matter from tree bark and other natural sources. The drawback of leather that is tanned with tannin is that it is less water resistant as well as heat resistant. If exposed to water the leather will become discolored, shrink and become harder and eventually brittle. In extreme heat this type of leather will become rigid and eventually will plasticize and become very brittle.

Alum tanned leather is made using aluminum salts that have been mixed with protein sources known as binders, such as egg yolk, flour and other similar substances. Leather purists may argue that this type of leather is not truly 'tanned', as the term 'tanning' comes from the tannin that is used in traditional leather production. This type of leather tends to be less supple than vegetable tanned leather as well.

Chrome tanned leather seems to be an improvement on both type mentioned above. Leather produced with chromium sulfate and other chromium salts



are more pliable and supple than vegetable tanned leather and will not discolor as easily in water or heat. Also, this type of leather allows for much more variety in terms of colors that can be produced.

Boiled leather is a type of vegetable tanned leather that has been hardened by soaking it in hot water or boiled wax. This type of leather has been used in more distant times for making armor and book binding.

Brain tanned leathers cannot as of yet be produced industrial, but require painstaking hand processing that includes the use of emulsified oils -typically made from those of animal brains. Brain tanned leather can be washed in water an are known for their extreme softness.