Chiang Mai Journal of Science

     The aim of the study was to investigate dyeing conditions that are appropriate for sedge fi bers with natural indigo dye as they usually do not absorb water. The conditioning of the fi bers is therefore essential in order to improve their water and color absorption properties. The conditioning process included soaking the fi bers in 1, 2, 3, 4, and 5% of sodium hydroxide (NaOH) with the ratio of the solution to sedge fi bers (a liquor ratio) of 50:1 for 24 hours. The conditioned fi bers were analysed for functional group changes by Fourier transform infrared (FTIR) spectroscopy and examined for appropriate conditions for natural indigo dyeing by using glucose as reducing agent instead of sodium dithionite (Na₂S₂O₄). Time and temperature variations were also used to identify suitable dyeing conditions. The fi ndings revealed that dyeing sedge fi bers with natural indigo dye and glucose as a reducing agent was most effective when soaked for 20 minutes at 40 °C. The dyed fi bers were examined for color strength (K/S) and color fastness. It can be concluded that 5% of NaOH is the most effective level of concentration condition sedge fi bers for natural indigo dyeing