Hiroto Tanamachi

Damage to Human Hair Caused by Repeated Bleaching Combined with Daily Weathering during Daily Life Activities

Background: Although it is well known that chemical oxidation with alkaline hydrogen peroxide damages human hair, little is known about the effects of bleaching during daily life activities which may alter hair components. Objective: To determine the effects of bleaching combined with daily weathering on lipids and amino acids in hair. Methods: Levels of lipids and amino acids were analyzed by chromatography in scalp hair fibers collected from three different females and in experimentally treated hair. Results: Bleaching combined with daily weathering induced the loss of 18-methyleicosanoic acid (18-MEA) and the conversion of half-cystine (H-CYS) to cysteic acid (CYS-A), which were the most remarkable changes among all lipids and amino acids tested. Although a single bleaching had no effect, repeated bleaching combined with daily weathering elicited significant decreases in other intrinsic endogenous lipids and alterations in amino acids that are characteristic for the cuticle. Conclusion: Hair damage, eventually leading to the worst damage such as splitting, is caused by bleaching during daily life activities and is mainly attributable to the loss of 18-MEA as well as the conversion of H-CYS to CYS-A.

Characterization of hair lipid images by argon sputter etching-scanning electron microscopy.

Hair lipid images, as visualized by argon sputter etching-scanning electron microscopy (ASE-SEM), reveal convex structures with a stitch pattern (SP) at the cell membrane complex (CMC) in the transverse hair plane. Based on interindividual variation, different features of the convex SP were classified into Types 0 to 4 with the corresponding scores 0 to 4. Observations using hair fibers collected from 27 Japanese females revealed significant positive correlations between the scores and the levels of exogenous lipids, which suggests that exogenous lipids internalized at the CMC predominantly constitute the convex SP. Intraindividual variation with different levels of exogenous lipids among hair fibers derived from individual females may be relevant to the uneven physicochemical properties of hair fibers on the scalp. Observations of 380 hair fibers collected from Japanese (Mongoloid), German and American (Caucasoid) females aged 3 to 77 yr demonstrated similar age-related changes in the lipid images, which represent an increase and then a decrease in levels of exogenous lipids with increasing age. This suggests that age-related changes in exogenous lipids are attributable to alterations in sebum excreted during aging and that this elicits age-related changes in physical parameters, which affect human hair texture.

Temperature as a moisture cue in haptics on hair.

A mechanism for giving a moisturized or dried‐out feeling to hair was investigated. A two‐step approach was conducted in order to elucidate the issue. First, we have reviewed previous studies that are related to the sensory perception of materials not only in cosmetic industry but also in other fields, such as textile and architecture industries, and established a hypothesis. Second, we have verified the hypothesis derived from the first step and identified the mechanism for the moisturized or dried‐out feeling that people feel by measuring the heat transfer characteristic, qmax. The results revealed that the moisturized or dried‐out feeling that people feel at the moment of contact with hair was highly related to the temperature drop at the skin surface. The results also revealed that the moisturized or dried‐out feeling strongly depends on the hair shape (meandering and diameter), surface damage and the water content of hair fibres which constitute the hair swatch. The moisturized feeling, however, was not related to the water content of hair fibres at a constant relative humidity (RH), as the differences in the water content of the hair fibres at a constant RH were too small for the recognition of the difference in the moisturized feeling.