Types of tanning agents
It is It is the oldest tanning method, using tannins extracted from vegetable matter. It is soft and brown in colour. This type of leather is not stable in water and is susceptible to discolouration. It becomes rigid if left to soak and then dry.
Invented in 1858, this involves the use of chromium sulfate and other salts of chromium. It is also known as ‘ wet blue ‘ because of the undyed leather’s pale blue colour. Usually it takes about a day to complete this method, making it suitable for industrial use.
Aldehyde Tanning – Chrome free Tanning
This involves the use of compounds of glutaraldehyde or oxazolidine. Because of its pale cream colour, it is called ‘ wet white. ‘ It is the main type of ‘ chrome – free ‘ leather, often used to make baby shoes etc.
Brain Tanning Leathers
These are obtained through a labor – intensive process involving the use of emulsified oils from animal brains like deer, cattle, and buffalo. They are known for their washability and softness.
Mixed with a variety of binders and proteins, such as flour and egg yolk, it is transformed using aluminum salts. The process is called ‘ tawing, ‘ and if soaked in water long enough to remove the alum salts, the resulting material transforms to rawhide.