Alum
A mineral salt, the most widely used mordant in Indian natural dyeing.
Also: fitkari, phitkari
Alum is a salt of aluminium, sold in Indian shops as fitkari. It is the mordant most often used for cotton, silk and wool, because it is cheap and gives clear colours. Cloth is usually soaked in an alum solution, often together with a tannin source such as myrobalan, before it is dyed. With madder, alum gives red. Alum also appears in the printed pastes of Bagru and Ajrakh. Because the amount and the care in washing change the result, printers keep their own recipes and treat them as part of the craft.