The types of dyestuff that are used by tanneries
generally varies depending on the product range needed along with the
dictates of the fashion world. It is a fact that each tannery uses
between 50-100 or more different types of dyestuffs.
The leather industry primarily uses anionic dyestuffs, that can be
divided in the following families:
- Acid dyes
- Direct dyes
- Mordant dyes
- Pre-metalled dyes
- Solubilised sulphur dyes
- Reactive dyes although a part of the anionic group of dyes but
use limited to a certain extent.
- Basic Dyes, its use is also limited.
If we see from the chemical point of view the dyes used are mostly
Azo dyes, Anthraquinone dyes and Triphenylmethanedyes. Commercially
speaking, popular Black dyes account for nearly 60-70% of all leather
dyeing. Also, out of this a dye variety called Acid Black 210 dominates
with 80-90% usage of all of the black dyes used.
Following are the few important tests that can be
undertaken for testing the colour fastness of dyed Leather:-
- Grey scale test to ascertain the change of colour and staining
- Fastness to light the standard Xenon lamp test
- Fastness towards mild washing
- Fastness towards washing by machine
- Colour Fastness with regard to migration into plasticized Poly
- Fastness towards perspiration
- Fastness to test of rubbing
- Fastness in water
- Fastness with respect to water spotting
- Solubility capacity of powder dyes
- Stabilty of dyes with regard to: