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Leather Dyes
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.

Latest in Leather Dye: Development of High Fastness Dyes

Applying high temperatures releases the fat-soluble components of conventional leather dyes out of their chemical bonds. Now these components has a tendency to migrate upwards into the layers whose task is to give the leather surface finish. This causes a visible change of color and intensity. What happens is that with the rising of humidity, it is quite likely that non-permanent dyes that are water-soluble, and low in molecular weight, will be washed out. Along with the problems like spotting and discoloration. Also there is the risk that migrating dye components can rub off on other materials such as plastics or textiles.

In comes the latest technology. The development and production of high-fastness dyes with no migratory secondary components is therefore a central factor in the manufacture of dyes for top quality leather products. The flow chart below describes the process criteria of selecting this dyes.

Latest Leather dye
Latest Leather dye

Criterias for determining the Colour Fastness of Dyed Leather

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 Vinyl Chloride
  • 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:
    • Acid
    • Alkali
    • Hard water



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