The outermost layer of skin, the stratum corneum (SC), plays an important role in protecting against desiccation and environmental challenges. Optimal hydration of the SC is essential for maintenance and promotion of skin health. Water helps to plasticize SC making it more flexible and resilient to mechanical stress1 and is also essential for the optimum biological functioning of the SC.2-4 Various factors including cleansing can cause a loss of hydration of the SC leading to varying degrees of SC dysfunction. Cleansers contain surfactants that interact with the proteins and lipids in the SC, which reduces the water retention capacity and leads to short-and long-term deleterious effects on skin condition. Use of mild surfactants in cleansers provides a significant benefit by reducing the loss of hydration during cleansing and by preserving the integrity of the skin moisture

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Dry Skin and Moisturizers: Chemistry and

barrier. In addition to this, cleansers, especially in the liquid form, can incorporate significant amount of emollients/moisturizers that can be delivered and retained on skin during cleansing to provide significant boost in skin hydration, in a lotion like manner. These emollient cleansers, unlike common cleansers, provide significant benefit to the skin such as prevention of dry, tight skin, and in some instances even dryness relief. Moisturizing cleansers when used as part of everyday skin care routine help maintain the SC in a healthy state. In the sections below we examine the importance of moisturization, the science and technology underlying mild and moisturizing cleansers, and methods to evaluate their performance.