Value-addition of silk using natural dye extracted from Lichen (Evernia cirrhatum)

Abstract

The natural dyes are used since pre-historic times for colouring the wide varieties of fibres for providing value addition, look and desire of the customer. In this study among the different sources of Lichen, Evernia cirrhatum was used to standardise the dyeing recipe for degummed silk cloth. A series of experiments were conducted to optimize the dyeing variables viz., medium of dye extraction, concentration of dye material, dye extraction time and dyeing time. The dyed fabric was then treated with chemical auxiliaries and fastness test was undertaken. Aqueous medium was used by taking 2 g of E. cirrhatum dye per 100 ml of water with 60 minute extraction time and 60 minute dyeing time was found to be optimum. In case of chemical auxiliaries, 2% of citric acid, 2% of sodium sulphate, 3% of oxalic acid and 4% tartaric acid with simultaneous dyeing method was found as best. It was observed that the dyed silk exhibited good to excellent colour fastness to washing and perspiration, no stain on rubbing and very good for light fastness. The chemical auxiliaries that exhibit best fastness characteristic were sodium sulphate and tartaric acid with fastness grade of good to excellent for washing and perspiration fastness, slight stain to no stain for rubbing fastness and good to very good for light fastness.