Ground water is commonly used media for most of textile processing treatments and it is often inherent with significant degree of hardness. This study is undertaken to evaluate the influence of water hardness on dyeing of cotton fabric by natural colorant extracted from flowers of Tagetes erecta. Response Surface Methodology (RSM) was applied for optimization of extraction and application of the natural colorant. Results were examined by Analysis of variance (ANOVA). In the present study, effect of process parameters viz. time (30–90 min), temperature (60–90oC) and concentration of hard water (250–1250 ppm) on natural dyeing process (K/S value) were modelled by employing RSM based central composite design. For the applications of natural colorants, mordanting technique was employed wherein the results of pre-mordanting and post-mordanting were studied comparatively. The dyed fabric was evaluated for colour strength (K/S) and CIELab values. It was observed that increase in water hardness adversely influenced the colour strength and it also adds to significant degree of unevenness in cotton dyeing using natural colorant.

Iqra Khalid, Shaukat Ali, Muhammad Tahir Hussain, Rizwan Ashra, Asfandyar Khan and Naseer Ahmad