Oily gels are commonly used to make stick and paste cosmetics and their physical properties are important for product performance and stability. Oil gelling agents for cosmetics are broadly classified into waxes, e.g. hydrocarbons and wax esters, and organo-gelling agents, e.g. sugar fatty acid esters and hydroxystearic acid. In this paper, the gelation mechanisms of various gelling agents are systemically explained and the relationship between the physical properties of gels and the performance of cosmetics, such as stick hardness, application feeling and coating gloss, are clarified. The composition of plant wax (the mixture of candelilla wax and behenyl behenate) having a gelling performance equivalent to that of petroleum waxes, which were developed on the basis of crystal control technology, is also described. Furthermore, the physical properties of gel films which are formed by the application of gels to skin or lip are analyzed by a quartz crystal microbalance sensor and then the relationship between the type of gelling agents and the performances such as gloss, sustainability, and feeling of the films is explained.

The degradation patterns of melanin granules in cross-sectional bleached hair were studied using transmission electron microscopy. In ammonia- or monoethanolamine-bleached hair, melanin granules were decomposed from the inner to the outer layers of the hair. In contrast, in the carbonate- or persulfate-bleached hair, melanin granules were decomposed from the outer to the inner layers of the hair. These results were suggested to be related to the heterogeneous distribution of melanin granules in the cortex, differences of permeability to the hair and oxidative reactivity to melanin granules of bleaching ingredients. Using ammonia and carbonate bleach, melanin granules were homogeneously decomposed in the whole hair effectively.

The texture of powder cosmetics, such as “smoothness” and “moist feeling”, is one of the most important properties for a usability assessment. In general, we rely upon a sensory evaluation to assess the usability of cosmetics. However, such subjective evaluation tends to be vague, not only due to the lack of evaluators'skill but also due to the reproducibility error of environmental factors. Therefore, a highly reliable and efficient evaluation method using physical properties has been in demand. In the fields where powder products are handled, such as the pharmaceutical and food industries, the direct shear testing of the powder bed (DST) has been applied for evaluating the powder's flowability, as an important physical property in the filling process. In this study, the correlation between sense of use and physical properties was investigated by DST for powder ingredients and powdery foundations. As a result, it was found that the internal friction coefficient μ_i was correlated with “smoothness”, while the shearing cohesion τ_c was related to “moist feeling”. This evaluation method can be applied to powder ingredients as well as to molded powders. Furthermore, this method can precisely detect the differences in texture between powdery foundations obtained from different molding processes (i.e. dry and wet molding processes).

While one's first impression is clearly influenced by his/her facial features and expressions, the texture of facial skin is also an important factor that determines such impressions. We focused on the middle-aged males' wishes that they be seen as appropriately aged and youthful. We therefore attempted to investigate what governs the impression of youthful appearance. Examining visually, we confirmed that apparent age was related to “Wrinkle” evaluation scores whereas youthful impression was related to “Spot”, “Blood color”, and “Dull color of skin” evaluation scores. Furthermore, based on eye-tracking measures, the facial portion where remarkably longer gaze durations were observed for “youthfulness impression evaluation” as compared to “apparent age evaluation” was found to be the cheek, where skin quality is most likely discernible. When middle-aged males repeatedly used a model emulsion, their youthful impression increased only from short distances, where the skin could be well-observed. For middle-aged males who have experienced age-related changes in skin quality, daily skincare is an effective means of promoting a youthful impression.