Photodegradation of hair of different ethnicity after 1 year of exposure to natural weathering in Arizona


  • Abstracts of papers that were published in the IFSCC MAGAZINE, Volume 9, No 4, 2006


Natural weathering of hair in a relatively dry hot climate was carried out by exposing hair of different ethnicity to natural environmental conditions at a Q-Lab weathering station in Arizona. The appearance of hair fibers changed dramatically due to thinning and fusion of scales as well as fusion of individual hair fibers with each other (inter-fiber fusion) to form rod-like structures stuck together by solubilized, oozed out, gelled and finally hardened proteins. The hair became extremely rigid and brittle with radial cracks forming mostly smooth radial fractures and occasionally step fractures. There was also internal fusion of the cellular structure of the fiber. Hair fibers were characterized by scanning electron microscopy (SEM) and UV-visible microspectrophotometry. UV-visible spectra showed that natural hair color (melanin) plays an important role in protecting hair proteins, mostly by a sacrificial mechanism. Indian and Chinese black hair, which are rich in melanin, resist photochemical degradation much better than hair of European origin with moderate, low or no melanin content.