Abstract:
This research showed the method to improve light fastness property of local natural dyes on cotton and silk yarns through the finishing process with UV absorber and anti-oxidant. Four natural dyes were extracted from Lac (reddish purple), Garcinia bark (yellow), Marigold flower (yellow), and Annatto seed (orange). Then they were dyed on cotton and silk yarns without and with alum as mordant, and dyed yarns were tested for light fastness property. The lowest light fastness dye was selected for further study on light fastness improvement. It was dyed on cotton and silk yarns and yarns were finished at various conditions using Rayosan®C Paste as UV absorber and ascorbic acid as anti-oxidant. Results indicated that natural dyeing process with mordanting improved the fixation of all dyes on both yarns. Light fastness testing on four dyes indicated that Annatto seed dye showed the lowest light fastness property (standard blue wool scale of 1 on cotton and 2 on silk) and it needed for further treatment to improve its light fastness. Results showed that the dyeing process with Annatto seed dye, followed by the finishing process with ascorbic acid at concentrations of 20 g/L for cotton and 10 g/L for silk, produced dyed yarns with the best improvement of light fastness property (least color change when testing for light fastness). This dyeing and finishing processes increased wash fastness of yarns but did not affect yarn strength and elongation.