How should we develop cleansing products? It is important for cleansing products to remove dirt on the skin. But it is not enough. Gentle formulations are also required for the products. Further we do not just make gentle cleansing formulations. We must develop the total feeling and image gentleness. How to develop gentle cleansing products for skin is reviewed.

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Recently, the awareness of hair damage has been increasing, but the ultrastructual damage mechanism has not been thoroughly analyzed. We determined that we could assess the degree of hair damage through analyzing the parts of the ultrastructure which were subject to damage by visualizing water distribution in a damaged hair. The damaged hair which was swelled with water was frozen and fixed with liquid nitrogen, then a fine cross section of the hair obtained with a microtome, was observed with a cryo scanning electron microscope (cryo-SEM). Due to sublimation of water in cryo-SEM, the region containing much water tends to be observed as a cavity. As a result, many cavities, which were thought to be the cortex CMC (cell membrane complex), intermacrofibrillar matrix and melanin granules, were observed only in the damaged hair, not in the undamaged hair. Therefore, such ultarastructures were thought to be more susceptible to damage, resulting in water-localization to these structures. In addition, the extent of cavities in the cryo-SEM image was correlated with the physical properties of water swelling and rupture strength due to tension. The degree of hair damage can be analyzed by observing cavities in the hair with cryo-SEM.

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When evaluating the efficacy of cosmetic products, it is important to analyze the state of cosmetic products on the skin. Especially in case of make-up products, the state of them on the skin has a profound influence on the efficacy of make-up. Therefore, the detailed analysis of the make-up layer is important for the development of highly functional products. In general, the make-up layer on the skin has been analyzed visually, or using a digital microscope. However by those methods, only macroscopic or two-dimensional information can be obtained. It is impossible to evaluate the microscopic state of powder particles or the three-dimensional conformation of the make-up layer, though they are very important for product development. In this study, we established a novel method to analyze the state of the make-up layer on the skin by sampling the make-up layers from the skin and observing them using scanning electron microscopy (SEM). First, we investigated the method for sampling the make-up layer on the skin and selected the appropriate resin. Next, the sampled make-up layers were observed using SEM and the conditions for the observation were configured. Finally this method was applied to the evaluation of the function of make-up products. The difference of the state of the make-up layer attributed to the make-up technique, the collapse of the make-up layer during make-up deterioration, and the relationship between the dispersibility of the powder particles and the SPF value of the products were evaluated. As a result, the difference of the make-up layer recognized visually can be evaluated microscopically and objectively. The changing state of the make-up layer during deterioration can also be analyzed microscopically and the mechanism of the deterioration was clarified. As regards the relationship between the dispersibility and the SPF value, it was revealed that the distribution of the powder particles was directly linked to the function of the products. The established method enables us to analyze the state of the powder particles in the make-up layer on the skin and contributes to the evaluation of the efficacy of make-up products.

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Important basic functions of a make-up remover are cleansing capability and a refreshing feel. However, there is no cleansing product that fills both functions at once because the key features obtained by conventional formulation techniques have been mutually exclusive. This problem was approached from an interfacial science perspective, focusing especially on the fact that a process of “adding water” exists between the “make-up removal” and “wash-off” process. In thehope of establishing the preferred system, phase diagrams with various constituents were studied. Consequently, an anomalous system was constructed in which a reversed micellar oil solution, suitable for “removing make-up”, inverts the structure, via oil and water continuous structures to a micellar solution which is suitable for “wash-off” by “addition of water”. The reversed micellar oil solution was applied to the novel cleansing oil formula having (1) excellent cleansing capability that is identical to that of a conventional oil formula, (2) a refreshing feel like that of a lotion type, with little residual oil base; unobtainable through conventional technologies. This high performance cleansing oil presents a novel concept that solves mutually exclusive events by using suitable aggregation structures for cleansing processes through extensive research of the phase behavior of oil cleansing formulae during the cleansing process.

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In our previous report, we developed a method to predict the preservative effectiveness of cosmetics from a predictive formula on the basis of the Minimum Inhibitory Concentration (MIC). Using this method, we predicted the preservative effectiveness of approximately 500 cosmetics, which satisfied a specific condition, and inspected the accuracy of this method. Though these cosmetics had differences in ingredients, e.g., antibacterial ingredients, humectants, viscosity regulators, oils and fats, we confirmed that we could predict the preservative effectiveness of them by this method. The quantity of antibacterial ingredients in a cosmetic is decided by challenge tests of a series of the cosmetics which changes only the quantity of antimicrobial ingredients. To find the appropriate quantity, many examinations are needed. However, because an approximate value of antimicrobial ingredients can be calculated by this method, we can reduce the number of examinations and can develop a new product effectively.

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