Influence of Shade Depth on the Effectiveness of Selected Ultraviolet Absorbers in Reducing Fading

Abstract

This study evaluates the ability of seven ultraviolet (UV) absorbers to reduce fading of nylon colored with nine synthetic acid dyes applied at 0.5% and 0.05% owf con centrations. By including two concentrations, we could evaluate the influence of depth of shade on the absorbers' effectiveness. Specimens were treated with UV absorbers using one of two application methods: an exhaust bath at 100°C or an immersion treatment at room temperature. After treatment, specimens were exposed to 160 AFUs of light in a xenon-arc Weather-Ometer, then evaluated instrumentally to determine the amount of color change. The UV absorbers examined here provided only very limited beneficial effects. Only two had no detrimental effects on all dye/shade com binations to which they were applied, and their beneficial effects were limited to four to seven of the eighteen dye/shade combinations evaluated. Based on this research, we cannot make general recommendations regarding UV absorber use because some of the acid-dyed nylon specimens treated with UV absorbers exhibited no improvement in lightfastness, while other treated specimens actually exhibited greater fading or color change than their respective untreated controls. Further testing is needed to determine the effects of specific absorbers on specific dyes not examined in this study, because the effectiveness of each absorber appears to be dye and shade specific.