ABSTRACT
Skin cleansing liquids are products that clean and refresh the skin by removing soil or dirty materials to help keep the skin’s physiological condition normal. There are residual metabolites on the skin that are unstable and reactive with oxygen or deposited molecules. These reactions happen on exposure to the sun or skin microorganisms, and form harmful materials that lead to skin trouble. Thus, cleansing is a necessary daily skincare practice, even for normal skin. Furthermore, special care must be taken for sensitive skin or atopic skin, because of its vulnerability. In such troubled types of skin, cleanliness must be attained without contributing to their susceptibility (1). There are different types of cleansing products, developed and commonly used, depending on the types of materials to be removed from the skin, or the types of conditions in which it would be used. Typical types of commercial skin cleansing products are listed in Table 1 (2). Most of the common cleansing products contain a relatively high concentration of surfactants, and is applied with water to make foam before washing off thoroughly. Good lathering is the most important feature of these products, because sensory feeling of the rich and fine foam is the key factor of repeated use by the consumers, although the amount and quality of foam are not directly related to the detergency from a physicochemical viewpoint. On the other hand, fine and thick lather serves an important function in shaving foam preparations for smooth razor application. Ease of quick rinse and after-feeling are other factors that rule the quality of skin cleansing products. Refreshed and moist feelings are typical elements that fulfill the consumers’ desires, and refreshing seems more important for body wash, especially for Japanese consumers.
