Friction and Surface Temperature of Wet Hair Containing Water, Oil, or Oil-in-Water Emulsion.

The surface properties and the tactile texture of human hair are important in designing hair-care products. In this study, we evaluated the temporal changes of friction and temperature during the drying process of wet human hair containing water, silicone oil, or oil-in-water (O/W) emulsion. The wet human hair including water or O/W emulsion have a moist feel, which was caused by the temperature reduction of approximately 3-4°C. When human hair is treated with silicone oil, more than 60% of the subjects felt their hair to be slippery and smooth like untreated hair. Treating hair with O/W emulsion after drying made the subject perceive a slippery feeling because the surfactant reduced friction on the hair surface. These results indicated that both friction and thermal properties of the hair surface are important to control the tactile texture of the human hair.