Development of evaluation method of tactile sensation of human hair

The objective of this study is to evaluate the friction property of human hair in hair washing by a physical index. The reactive force during hair brushing was measured to establish a physical index, and verified by examining the correlation with the sensory evaluation. A hair sample was fixed by a tensile jig of universal tester, and drawn up by fixed velocity with a metallic brush inserted while the reactive force was monitored. By comparison between hairs processed by commercially available shampoos, it was confirmed that the integral of the reaction force against the combing distance had a good correlation with the sensory evaluation score of “squeaky”. In addition, the result of the frequency analysis on the temporal fluctuation of the reactive force also showed good correspondence with the sensory evaluation. From these results, the possibility of objective evaluation of tactile sensation of human hair was shown by the integral of reactive force and the frequency analysis.