The Effect of Metal Mordant and Biomordant on Color Strength of Dyed Woolen Yarn with Natural Dyes

Todays, there is a strong tendency toward eco-dyeing with natural products. Several natural dyes have been used for dyeing protein fibers such as wool and silk fiber. This work examines the effect of metal mordant and biomordant on the color strength of dyed woolen yarn with madder, weld, and pomegranate natural dyes. The wool was mordanted with alum metallic and colorless mordant as well as walnut as colored and biomordant in pre-mordanting method. The madder, weld, and pomegranate natural dyes were extracted via ultrasound-assisted extraction (UAE). The woolen yarn was dyed with concentrations of 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100% WOF of natural dyes. The absorption behavior and dyeing properties of natural dyes were explored by measuring the reflectance spectra and colorimetric parameter of dyed samples. The spectral derivative method was used to analyze the reflectance spectra. The color strength of natural dyes was evaluated by measuring the K/S as reflectance function at lambda(max) (SWL), SUM, WSUM, F-K, KSgm, KSf, SKSf, and the first-order derivative of K/S spectra. The colorimetric study indicated that the color of the dyed woolen yarn changed with alteration of the mordant. The statistical analysis revealed that there were significant correlations between the first-order derivative of K/S spectra d1(K/S) as a new color strength parameter and other color strength parameters such as SWL, SUM, WSUM, KSf, SKSf, and color strength parameters. The obtained results indicated that the color strength of the natural dye with alum as metal mordant was greater than that of walnut as colored and biomordant. The study of fastness properties of dyed samples with madder and weld natural dyes showed that the wash and light fastness of the sample with alum mordant were better than those of walnut mordant. However, the samples dyed with pomegranate natural dye indicated that the wash and light fastness were the same for alum and walnut mordants.