Soap is created by a heating process called saponification; an alkali and a long-chain fat compound are combined, producing a fatty acid salt which exhibits detergent properties (6). A surfactant effect from usage of a soap reduces surface tension between water and surface debris, allowing for separation and removal by a lathering effect. A major difficulty with basic soap formulation is a pH of >7 (usually pH 9-10); the normal pH of skin ranges between 4.5-6.5 (6). The use of true soaps commonly leads to unacceptable dryness and irritation.
The development of soap-free synthetic detergent (“syndet”) bars and non-lipid liquid cleansers has significantly improved the cosmetic acceptability and tolerability of skin cleanser formulations (6,29). Syndet bars are efficacious cleansers formulations, effectively limit damage to the epidermal barrier, and are widely accepted and very popular in the marketplace (6,30). These formulations are comprised of < 10% soap and sustain an adjusted pH of 5.5-7 by utilizing synthetic detergents (“syndets”) and filler substances that are associated with effective cleansing and little to no irritation (6). Lipid-free liquid formulations are also effective cleansers which may create a thin moisturizing film and produce little to no irritation in patients with normal, sensitive, photoaged, or diseased skin (6). They are also effective in the removal of cosmetics and makeup. Major components of non-lipid liquid cleansers include water, cetyl alcohol, stearyl alcohol, and glycerin (6).
The terms gentle or mild do imply that irritation is significantly minimized or absent due to the combination of ingredients and adjusted pH of the formulation, and do not imply a lack of efficacy. Several studies support the efficacy, high degree of patient preference, and lack of irritation associated with use of syndet bars and non-lipid liquid cleansers (6,31). Some combination bars (“combars”) utilize additives to improve the “feel” of the formulation and reduce dryness through creation of a superfatted soap or by addition of humectants (i. e., glycerin). However, these formulations usually sustain an alkaline pH > 9, and some tend to dissolve rapidly during usage (6).
The primary goals of skin cleansing and moisturization are to sustain overall skin health and appearance by maintaining epidermal barrier integrity. This is achieved by selecting
products that are formulated to preserve retention of water content, limit damage to epidermal lipids and proteins, minimize TEWL, and contribute to barrier repair during episodes of compromise. Optimal product selection is based primarily upon the inherent qualities of the formulation, correlated with the needs and skin type characteristics of the individual patient. Ultimately, effective products are well designed with regard to their fundamental skin care characteristics and not dependent on multiple special additives that are included based on marketing trends rather than scientific validity.