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«“√ “√ √“™∫— ≥±‘ µ¬ ∂“π Usa Sangwatanaroj, et al. 145 ªï ∑’Ë ÛÚ ©∫— ∫∑’Ë Ò ¡.§.-¡’ .§. Úıı shown previously that the Chinese degummed filament has a higher loss of tenacity than its raw fila- ment after sunlight exposure. This could be explained by the fact that the resistance to sunlight of the Chinese filament is influenced more by the sericin content than by other factors. For the local fila- ments, most of the raw filaments and degummed filaments showed a similar loss of tenacity and thus the sericin on filaments might not play a significant role in protect- ing the local silks from sunlight. Instead, the silk fibroin of the lo- cal filaments (amino acids, natural pigments) could play a major role. In terms of reeling techniques, it was shown that most of the local silks reeled by hand and by ma- chine had similar tenacity loss af- ter the exposure. There might not be a relationship between the reel- ing method and the resistance to sunlight of the silk filaments. Dyeability The degummed silk filaments were dyed with acid dye orange 253 and they were measured for %dye fixation. The results in Figure 5 indicated that these filaments showed %dye fixation in the range of 72-85%. The Chinese filament had the lowest dye fixation of 72% while the local filaments had a higher fixa- tion of 74-83%. In this study, the dye fixation was calculated from the measurement of silk color strength (K/S) before and after washing (see the dyeability sec- tion) using a colorimetric method. This method showed the color strength of the silk surface, not within the silk filament. Therefore, the silk filament with a higher sur- face area or smaller size (denier) would show lower color strength than the silk filament with a lower surface area or larger size (denier) when they were dyed at the same dye concentration because the smaller silk needs a higher amount of dye or needs to be dyed at a higher dye concentration in order to obtain the same color strength as the larger silk. This could be the reason that the smaller denier of the Chinese silk filament reeled by machine (see denier section) showed a lower dye fixation than Dye fixation (%) Degummed silk fibers C4 (hand) C4 (m/c) C6 (hand) C6 (m/c) C1 (hand) C1 (m/c) Chi (m/c) 100 80 60 40 20 0 Figure 5. Dye fixations of the degummed silks. [Cl for local Thai Silk; C4 for Chul 4; C6 for Chul 6; Chi for Chinese filaments; hand for hand reeling; m/c for machine reeling]