Dyeing of polyester and wool with solvent-assisted color extract from ratanjot

Abstract

A series of homologous alcoholic solvents and their mixtures has been used for the extraction of coloring matter from ratanjot (<i>Onosma echoides</i>) powder. The extracted coloring matter is then used for dyeing of wool and polyester fabrics. The dyebaths are prepared based on aqueous, solvent and solvent assisted dyeing mediums. It is found that as compared to a single solvent, a mixture of solvents results in higher extraction of colorants from ratanjot. Also, the depth of shade reduces with increasing hydrophobicity of the dyeing medium using the same extraction medium. While the fastness to washing (change in color) is found to be good to excellent (3-5) on polyester, it is rather low (1-3) on wool. This can be attributed to the hydrophobic nature of colorants extracted from ratanjot, which resemble disperse dyes and have poor wash fastness on wool but show good wash fastness on polyester.