In this process the fabric is treated with a solution containing Harda powder. The process of Harda treatment with intermediate drying is repeated 2-3 times till greenish yellow colour is obtained. The fabric is then dried either in sunlight or in shade. The purpose of harda treatment of cotton fabric is to hold the metal on fabric by reaction with tannin present in harda. This metal ion is then subsequently available for reaction with the colouring component/s of the vegetable dyes applied subsequently by dyeing or printing techniques. From the natural dyeing point view only Alum and iron salts are environmentally friendly. The other salts like copper sulphate, sodium dichromate and stannous chloride are not environmentally friendly. Therefore, although they are suitable as mordant for natural dyes they are not recommended on environmental and toxicity grounds.