Morphology and properties of Asian and Caucasian hair.
Various aspects of Asian and Caucasian hairs were investigated and compared. We started by studying their cuticle structures--the number of cuticle layers, width of the cuticle cells, degree of their inclination, and the interval between surface cuticle edges. As a result of this study, on about two hundred subjects for each race, it was shown that there were statistically meaningful differences between all these attributes for the two hair types. Asian hair has more cuticle layers and wider cuticle cells than Caucasian hair, and the cuticular inclination of Asian hair is steeper and its cuticular interval is narrower than in Caucasian hair. In addition, it was also found that there are differences in how cuticle cells begin to fail. Under extension stress, Asian hair cuticles fail as large pieces while keeping their original shape. On the other hand, Caucasian hair cuticles tend to collapse to form small fragments. AFM measurements revealed that Caucasian cuticles are indeed more fragile than Asian cuticles. These results suggest that the strength of cuticular subcomponents is different between Asian and Caucasian hair and that the weakest point, where stress is first absorbed, differs between races. It was proven that the cuticles of Asian hair are more easily peeled off than Caucasian hair cuticles during daily grooming. This can be attributed to the difference in how stress is absorbed.
Takahashi
T
T
Hair-Care Research Laboratories, Kao Corporation, 1-3, Bunka 2, Sumida-ku, Tokyo, 131-8501, Japan.
Hayashi
R
R
Okamoto
M
M
Inoue
S
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People; D004548:Elasticity; D005260:Female; D006197:Hair / Q000737:chemistry* / Q000648:ultrastructure*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D044465:White People