Alteration of Human Hair by Cosmetic Prccessings

The influences on human hair by cosmetic processings such as coldwaving agent, bleaching agent, shampooing agent and brushing were studied.In this paper, the change of properties of hair was studied by the methods of an extension test and a dye adsorption test to evaluate the influence on essential structure of hair, and also by the methods of an observation with a scanning electron microscope and a split-end formation test to evaluate the visible surface changes of hair.After careful examination, two unique test methods were found useful. One is an extension test by which the difference in extension between the treated half part of a hair shaft and the other untreated half part as control is measured.The other is an observation method by a scanning electron microscope on the surface condition of the same hais used in the previous test.The influence by coldwaing and bleaching agent on hair was greater than that by surface active agents in shampoo.In comparison of the influence by the coldwaving agent and the bleaching one, the former mainly alters the properties of the essential structure of hair, whereas the latter affects the surface state of hair.It was also found that for shampoo formulation alkylethersulfate was preferable to the surface active agents such as soap, ABS and SDS.The process of the formation of hair split-end is so interesting. That most hair split-ends were derived from fine cracks formed at the weaker points on the hair shaft. The fine cracks gradually grow larger than the hair was snapped off at the crackpoint by mechanical forces such as brushing. The formation of split-ends were ovserved as a new tip of hair. It was found the mechanical forces of brushing conbined with soap, bleaching agent, and hair dye exert greater influence on the formation of hair split-ends.