Effectiveness of sal, Shorea robusta Gaertn. f. bark dye on mordanted silk

Abstract

The effectiveness of sal (Shorea robusta Gaertn. f.) bark dye on silk fabric treated with four different mordants was studied. Four types of mordants, viz. alum, CuSO₄, Al₂(SO₄)₃ and citric acid were used, each at 1, 2 and 3% of weight of fabric (o.w.f.) and with material liquor ratio (MLR) of 1:40.The variations in colour and intensities were analysed with the help of Hunterlab colour scale. It was observed that the maximum change in colour with respect to undyed silk fabrics was for 3% CuSO₄ mordant treated samples with the ΔE* value of 48.52±0.14. However, the values were not significantly different from samples treated with CuSO₄ at 2% level. The change in chroma (ΔC*) was also maximum for the 3% CuSO₄ mordant (37.41±0.40). The colour fastness analysis with respect to washing, rubbing and sunlight also indicated that all mordants and concentrations used in the study excepting 1% alum offered adequate fastness characteristics. Unmordanted samples had moderate fastness. In view of the colour fastness with respect to washing, rubbing and exposure to light, the sal dye can be applied with any of the selected mordants at 3% level.