Dyeing of wool and silk with Bixa orellana

Abstract

Silk and wool fabrics have been dyed employing extract of seeds of annato (Bixa orellana) in absence and presence of magnesium sulphate, aluminium sulphate and ferrous sulphate. Colouration of both the fibres is found to be most effectively accomplished at pH 4.5 commonly in the absence and presence of such inorganic salts. Colour uptake for wool is found to be more than that for silk under all the conditions studied. The use of ferrous sulphate produces significant improvement in colour uptake when both the substrates are treated with such salt prior to application of annato. Coloured protein fibres, in general, produce light and wash fastness ratings of 2-3. Ferrous sulphate, however, improves colour fastness properties and colour retention on washing of wool and silk fibres.