Analysis of the Effect of Mordants on the Degradation of Alizarin in Silk Dyed with Natural Madder Dye

This research investigated the effect of mordants on the degradation of madder dye in silk when silk was treated by the H2O2/UV condition as a laboratory simulation of burial induced degradation. Alum, iron, and alum/iron composite mordanting methods were applied to silk before dyeing with madder dye. Dye extracted from silk was examined using HPLC-DAD-MS analysis. The abundance of the chromatogram peak at 8.88 min retention time was used as the concentration of alizarin pigment in silk. K/S values, CIE $L^{\ast}a^{\ast}b^{\ast}$ values; in addition, Munsell HVC values were obtained using a spectrocolorimeter. The findings indicated that alizarin degraded most severely in silk mordanted by alum/iron composite mordanting than alum mordanting or iron mordanting. Mordanting with alum alone provided a relatively lower dye fixation at the point of dyeing; however, it provided a better survival of alizarin after 12 hours of degradation treatment.