Tribological method to objectify similarity of vague tactile sensations experienced during application of liquid cosmetic foundations

To develop objective estimation methods for the tactile sensations experienced during the application of liquid cosmetic foundation (i.e., emulsion foundations (EFs)), a tribotester based on the mechanical properties of human skin was used in lubrication experiments with EF samples. From the time-varying signals of the tangential spring deflection obtained in reciprocating rubbing tests for small sample amounts, trajectories (i.e., plots of the tangential spring deflection against the tangential drive position) were obtained. Using characteristic trajectory shapes (e.g., a shape like a ribbon with jagged edges) makes it possible to evaluate the similarity of vague tactile sensations without sensory testing.