Any salt of chromium, with either mineral or organic acids, can be used, but chrome alum is the one most commonly employed.
In any of these methods the chrome alum liquor is suitable, using 10 per cent.
Iron alum (pale mauve) and chrome alum (deep purple) are compounds containing iron and chromium in place of aluminium.
The disadvantage of this liquor is the limited solubility of chrome alum and the need for its solution in the cold.
Of the first type the most common is that in which chrome alum (a bye-product of the dyeing industry) is the starting-point.
In dyeing with coal tar colours the alizarin colours may be used after mordanting with chrome alum.
For special purposes chromium fluoride, chrome alum, &c., are employed.
A favourite mixture consists of chrome alum and sodium carbonate (common soda).
This liquor has a greater plumping effect on the leather than the chrome alum liquor has.