This article reviews the optical properties of pigments used in make-up cosmetics. In white pigments such as titanium oxide and zinc oxide, particle size is controlled between 150 and 400nm to maximize light scattering. Inversely, since the absorption of ultraviolet light is the purpose of employing titanium oxide microparticles in cosmetics, their particle size is reduced to less than 50nm so as to maximize ultraviolet absorption and to minimize light scattering. The colors of pigments containing transition metals such as iron and cobalt are caused by the absorption of visible light, but light scattering takes part in their tones of color. In nacreous pigments, a variety of pearly luster effects are created by utilizing the light interference in a TiO2 or Fe2O3 thin film coated on mica platelets. Irridescent effects are given by the combination of the interference effects and the light absorption by colored materials deposited on a TiO2 thin film. As a extender pigment for foundations in cake form, TiO2-Al2O3 doubly coated mica is prepared, which shows the appearance of natural luster and has excellent whiteness.
