Effect of Light upon Wool: Part III: Post-Irradiation Loss of Color in the Dark after “Germicidal” UV Exposure

Abstract

The green color acquired by wool during irradiation with Germicidal ultraviolet in air was found to “fade” rapidly in the dark in post-irradiation reactions. The loss of color, resulting in a pale yellow, is due to the practically complete disappearance of the orange absorption band and the partial disappearance of the violet-blue absorption band, which together cause the green color. Both absorbers disappear in thermal reactions by reacting with water vapor and/or oxygen at rates governed by the concentration of these gases and by the temperature of the wool. The energy of activation of the reaction governing the disappearance of the orange absorber is approximately 12,000 calories. This report, in showing the considerable activity in wool after the initiating uv has been discontinued, provides an example in the neglected field of post-irradiation effects.