Applied Cosmetic Science and Technology Applied Cosmetic Science and Technology

Thickening agents are important raw materials for controlling the tactile sensation of cosmetics. We evaluated the friction properties of the skin-care creams SC1 and SC2 containing carbomer or carbomer Na using a sinusoidal motion friction evaluation system in which a contact probe moves under nonlinear motion. When skin-care cream was applied to the human skin, the friction coefficient was significantly lower than that of untreated skin. The friction coefficient during the application process of SC1 was 0.37 ± 0.11, which was lower than that of SC2, 0.51 ± 0.14. The friction pattern changed with the type of skin-care cream. The expression rate of the oscillation pattern was decreased by applying the skin care cream, while the stable pattern, in which no significant oscillation was observed, was increased. The expression rate of the oscillation pattern was lower during the application process of SC1 than that of SC2. The friction properties of each skin-care cream were attributed to rheological properties: The yield stress of SC1 was twice greater than that of SC2 at 15 Pa, and the thickness of the liquid film between the skin and the contact probe was maintained even when shear force was applied during application. These results indicate that SC1 has a low friction coefficient and a low expression rate of oscillation patterns due to its high yield stress and thick liquid film that provides sufficient lubrication. These findings will be useful in controlling tactile sensation, that is, smoothness, spreadability, and usability during the cosmetics application process.