Introduction
Natural dyes refer to those colourants which are obtainedfrom plant, animal and mineral resources. These are used for colouration oftextile, food, drugs and cosmetics. Small quantities are also used forcolouration of paper, leather, shoe-polish, wood, candle etc. The main naturaldyes used in India have been extracted from the roots, barks, flowers andfruits of various dye producing plants. Mollotus phillipinensis is asmall evergreen tree belonging to the Euphorbiaceae family, mostly natives oftropics of old world, flourishing in the forests of tropical Asia from India to Malaysia and Phillipines, China and Australia. The tree bears fruits in the form of pods.The dye is an orange-red powder, which occurs as a glandular pubescence on thosepods and is gathered by shaking the ripe capsules harvested in the month ofFebruary-March. The colouring matter of Mollotus phillipinensiscomprises of several chalcones, the structures of which are given in theliterature. Rheum emodi, commonly known as dolu, is a stout herbof 1.5-3 m in height, distributed in the Himalayas from Kashmir to Sikkim at an altitude of 3300-5200 m. The stout roots are the chief source of Himalayanrhubarb and finds application chiefly in medicine as a purgative and astringenttonic and can also be used for colouration of wool and silk fibre. The chiefcolouring component of Rheum emodi is chrysophanic acid and thestructure of which is given in the literature. Ratanjot (Onosma echoides)has traditionally been used as a food colourant. The bark of roots containsseveral naphthoquinone pigments, which give a violet-red colour. The mainpigment is believed to be alkanin. Alkanin is insoluble in water but has beenused to dye wool, silk and cotton with addition of alcohol for one hour at 400Cand its alkaline solution is deep blue coloured.
Natural dyes are mostly used to dye natural fibres like,cotton, wool, silk, jute etc. But very little information is available ondyeing of synthetic fibre like polyester with natural dyes. In this study anattempt has been made to dye polyester fabric with those above mentionednatural colourants in absence and presence of different inorganic salts ormordants. The dyed fabrics were assessed in terms of depth of shade anddifferent colourfastness properties.
About the Author
Sankar RayMaulik is Lecturer at Visva Bharati University in the Department of SilpaSadana (Textile section), Sriniketan, Dist. Birbhum, West Bengal.
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