Photodegradation of human hair: An SEM study

Abstract

The effects of both relative humidity and spectral energy distribution on the photochemical oxidation of the hair fiber are studied. Results obtained at various relative humidities in two different fading units, namely, the QUV Accelerated Weathering Tester and the Atlas Weather-Ometer © (AW) are compared. Scale thinning and fusion observed during UV/humidification cycling are greatly reduced with exposure at low humidities without humidification cycles. Upon post-treatment with water, fibers irradiated at a constant 10% RH in the QUV show scale thinning and fusion similar to that of fibers exposed to UV/humidification cycling. This indicates that photodegradation occurs at low humidity as well. Fibers exposed at constant 20%, 50%, and 70% humidity in the AW show only moderate scale thinning, even after post-treatment with water. The total solar spectrum used in the AW apparently causes less severe photodegradation of the proteins than the UV light of the QUV.