Abstract
We observed finishing of cosmetic foundation every day on the same skin to investigate the day-to-day variations in finishing which are often felt by many foundation users. We hypothesized that the adhesion of foundation to the skin varied every day because of daily changes in some conditions on the surface of the skin to which the foundation is applied. Therefore, 15 women in their 30s using a powder-type foundation were used as volunteers. We observed their finishing and determined the condition of their bare skin surface every day for 1 month. The items of determination for the skin were moisture content, sebum and elasticity, and the items given an observation score were scaling, acne, pores and color unevenness. As a result, we found that foundation finishing varied day to day for each subject even when they used the same foundation every day. The types of variation were categorized as “dry-appearance” and “uneven-appearance”. Bare skin condition also varied day to day. Correlation analysis between variation of foundation finishing and variation of bare skin condition with respect to each subject showed that “dry-appearance” variation correlated to changing scaling and/or acne on skin surface in plural persons. It is supposed that daily variations of asperity on the skin surface affect the adhesion of foundation to the skin, and enhance “dry-appearance”.
