Perception of Translucency and Glossiness: Influence of the Optical Scattering Properties on Sensory Evaluation

In the cosmetics industry, fine particles suspended or dispersed in a medium are widely used. Optical properties of the medium can be an indicator for evaluating the performance of cosmetic product, such as the ultraviolet protection capacity of sunscreens and also its appearance. However, the relationship between the optical properties and the appearance of the product has not been clarified. In this study, dispersions of fine particles with titanium dioxide or zinc oxide were used as scattering medium to clarify the relation between their scattering properties and changes in visual perception. For visual perception, sensory tests with human panelists were performed using a custom-designed apparatus to inspect the samples and evaluate the two visual sensory quantities, “glossiness” and “translucency”. The sensory test employed Thurston’s one-pair comparison method, and a total of 18 panelists were asked to evaluate the samples. The sensory tests showed that the translucency became stronger as the scattering coefficient decreased. On the other hand, only the samples in the group with the highest scattering coefficient showed a slightly low glossiness. In contrast, the other samples showed little difference in glossiness due to the difference in scattering coefficients. The results of this study indicate that the appearance of cosmetics products can be influenced by controlling the scattering properties of the medium.