Relationship between hair surface properties and tactile sensation

The degree of hair damage can be detected by touching the hair with one's fingers. Therefore, to quantify the degree of hair damage and clarify the relationship between tactile sensation and hair surface properties is important. There have been many studies regarding the changes in hair surface properties due to damage and the recovery effect noted with hair care products. However, few studies have examined the relationship between hair surface properties and the recognition of damage. In part this is due to the fact that there has been no objective device to measure the state and degree of damage to hair, which exhibits significant individual variation. In this study, we developed unique artificial hair surface model plates that specifically represent non‐damaged and damaged states of hair and reduce the individual variation in results that occurs frequently when real hair is used. The tactile sensations of four different types of hair surface model plates were evaluated by touching and rubbing them. The results showed that a wider cuticle and an irregular order of cuticle structure were essential to feel hair damage. The tactile sensation of damaged hair is influenced more by the shape of the cuticle under dry conditions although fingers can recognize a hydrophilic surface and can feel hair damage when the surface is touched and rubbed even under dry conditions. Furthermore, the tactile sensation of hair damage and the improvement effect of the tactile sensation can be qualified as a coefficient of dynamic friction using the hair surface model plates and a tactile friction meter. Therefore, the hair surface model plates are potential tools to evaluate hair damage more objectively and should prove useful in testing various toiletry products.