Abstract
The aqueous solutions of some dyes, such as Benzo Azurine G (BAG), Cu-complex dye derived from BAG (Cu-complex) and Congo Red (CR), were exposed to the light of mercury quartz lamp or to a carbon arc lamp. In order to make use of the ultra-violet rays and the visible rays of mercury quartz lamp, two filters, UV-DIC and V-Y3C, were respectively used. The absorption spectra of the dyes were measured at convenient time with a spectrophotometer, and the exposure of the dye solutions to the rays were continued again.
The results of this experiments are as follows:
A Cu-complex dye which has a high resistance to light fading in a cellophane films (cf. our previous report) shows no appreciable difference in the decrease of optical density in a aqueous solution, compared with BAG. By the selected light, such as λ=3000_??_4000Â rays, the aqueous solutions of the above-named two dyes are faded in the same degree, and by the other light BAG is more easily faded than by the Cu-complex. CR is faded more rapidly than other two dyes under the exposure to carbon arc lamp.
