The texture of powder cosmetics, such as "smoothness" and "moist feeling", is one of the most important properties for the usability assessment. In general, we rely upon the sensory evaluation for cosmetics. However, such subjective evaluation tends to be vague because of not only the lack of evaluators' skill but also the reproducibility error on environmental factors. Therefore, a highly-reliable evaluation method by using physical properties, such as particulate mechanical characteristics, is desired.
In this study, we investigated the correlation between the sense of use and physical properties by the direct shear testing of the powder bed for five kinds of cosmetic powder. As a result, we found that internal friction coefficient μi was correlated with the "smoothness". Furthermore, the shearing cohesion τc and the degree of PYL （Powder Yield Locus） curve were related to "moist feeling", respectively.
