ABSTRACT
Hydrating substances are used in cosmetic products to retard moisture loss from the product during use and to increase the moisture content in material in contact with the product. This function is generally performed by hygroscopic substances, or humectants. In the International Cosmetic Ingredient Dictionary 66 substances are listed as humectants and 76 hygroscopic materials are used to increase the water content of the skin [1]. The resulting effect of the substances depends on their inherent hygroscopicity at different humidity, as well as their volatility and penetration characteristics. Some factors to consider during product development are highlighted in Table 1.
