Enhancing the color shade and depth of linen fabrics dyed with Caesalpinia sappan L. wood extract using metallic salt mordants

This study demonstrated natural dyeing of linen with a dye extracted from sappan wood (Caesalpinia sappan L.). Four metallic salt mordants, namely (NH4)2Fe(SO4)2, CuSO4, SnCl2, and AlK(SO4)2, referred to as Fe, Cu, Sn, and Al, respectively, were used to improve the dyeing properties. The influences of the pH, dye concentration, mordant type and concentration, and mordanting technique on the dyeing properties were investigated. Dyeing without mordants resulted in a reddish-brown fabric; however, different mordants produced a variety of color shades. In general, the mordant containing Fe yielded the highest color strength, generating a dark gray color very close to black. Crimson and magenta fabrics were obtained using Sn, and pink fabrics were obtained using Al. The samples with the Cu mordant showed a dark and dull purple color. The color strength due to post-mordanting was higher than those due to pre- and meta-mordanting. Dyeing and mordanting increased the ultraviolet protection factor (UPF) of the fabrics. Only the fabrics post-mordanted with Fe exhibited good ultraviolet protection (UPF 15). The concentrations of extractable heavy metals (Fe and Cu) were also determined.