Stability of Carthamin and Safflor Yellow B on Silk Powders under Continuous Irradiation of Fluorescent or UV-C Light

A weighted amount of carthamin and safflor yellow B was fixed separately with silk powders in solution and fluorescent or UV-C light irradiated at different temperature ranges with changing light irradiation intensities. Positive bleaching of both red (carthamin) and orange yellow (safflor yellow B) colours was pronounced closely upon test intervals at varied radiation intensities. Under fluorescent light, safflor yellow B was more unstable than carthamin (average bleaching ratio, carthamin: safflor yellow B=1.0:2.5), while with UV-C light irradiation, a reversed tendency was shown between carthamin and safflor yellow B (average bleaching ratio, carthamin: safflor yellow B=2.7:1.0). Under an experimental condition with different temperature ranges tested at 4, 25 and 50°C, carthamin was bleached at lower temperature ranges indicating following rates (99.0: 24.0: 8.0). On the other hand, safflor yellow B was unstable at higher temperatures (7.9: 13.4: 27.6).