A Study of Some Factors Affecting the Photodegradation of Textile Yarns Part I : The Spectral Distributions of Sun-Sky and Xenon-Arc Radiation

Abstract

A detailed study was made of the relative spectral distribution of sun-sky radiation at several times of day under various sky conditions from June to October 1971. A sufficient number of spectra were recorded to provide a statistically viable sample. Average spectral distributions for three daily time periods and four classes of sky conditions within four approximately monthly periods were calculated and compared. Radiation from a sunny-bright sky over the noon period gave a representative average and would be a reasonable standard sun-sky spectral distribution for comparison with artificial light sources. The relative spectral distribution of xenon-arc radiation in combination with various filters was monitored using the same spectrographic equipment. Comparison of the sun-sky spectral distribution with the xenon arc emission spectrum indicated that although agreement of the lower cut-off wavelength could be attained using Q/Q/WG filters. Xenon radiation was deficient above 3150 Å regardless of the filter system used. Infrared filters removed an undesirable amount of high energy radiation and would be likely to decelerate degradation.