2012 Volume 53 Issue 4 Pages 285-293
The influence of two major components of natural dyes, hematoxylin and curcumin, and two mordants, iron sulfate (FeSO4・7H2O) and aluminum potassium sulfate (KAI(SO4)2・12H2O), on the photodegradation rates of linen fibers were investigated. Samples were dyed and mordanted according to a traditional Japanese procedure and then exposed to xenon arc lamp light in incremental doses for up to 20 or 40 days.The effects of irradiation by xenon light were compared with those of irradiation by infrared light. The photodegradation of linen fibers dyed with curcumin and mordanted with aluminum potassium sulfate showed the most rapid color fading among all the dyed and mordanted linens but showed the least reduction in breaking load. Samples dyed and mordanted with aluminum potassium sulfate showed generally rapid color fading when exposed to xenon light. All dyed and mordanted linens exposed to infrared light showed less color fading than those exposed to xenon light. Photodegradation of linen fibers mordanted with iron sulfate caused the greatest decrease in breaking load, which confirms the degradative acceleration effect of iron salt. The photodegradation of linen fibers dyed with hematoxylin and either of the two mordants caused a rapid decrease in breaking load under exposure to infrared light. This suggests that the degradation caused by light is due not only to heat. Those samples exhibit an increase in cellulose oxidation in slight increases in temperature. From our results, it was concluded that, in the case of linen dyed with hematoxylin and mordanted with iron sulfate, degradation of the fiber was caused by light as well as slight increases in temperature.
