Natural and synthetic layered materials as cosmetic ingredients
Natural and synthetic layered materials arerecently incorporated in several health care formulationsalthough therapeutic effects of clay minerals were usedsince prehistoric times. This article summarizes thebeneficial effects of natural and synthetic layeredmaterials for cosmetic formulations. A broad descriptionof smectites (mainly montmorillonite and hectorite) andof layered double hydroxides (LDH) is discussed in termsof rheological behaviour in the dispersion medium. Themechanism of gel formation of these layered materials inaqueous and non-aqueous system is described. Thispaper also reviews the properties of layered materialsdispersions and the different functions derived from thoseproperties, providing examples of applications incosmetic products. The performance of cosmetics isenhanced by the use of layered materials which allowgood colour retention and coverage for nail lacquers,lipsticks and eye shadows. They have also been tested tobe non-irritant for both skin and eye contact.