It is difficult to achieve a ‘dream tan’ when using products with high sun protection. Self-tanning products are an increasingly important segment of the sun care market, as consumers want to achieve a tanned look without compromising their health. Self-tans are considered safe and are a perfect solution for those who want to enjoy a tan without having to expose themselves to UV radiation. The base component of self-tans is dihydroxyacetone (DHA), which reacts with amino acids in the stratum corneum of the epidermis and gives a brown colour a few hours after application. However, as DHA does not stimulate melanin synthesis and does not protect against UV radiation, sunscreens should still be used to protect the skin. The addition of pigments is desirable in self-tan formulations because it provides an instant bronzing effect and improves the immediate appearance of the skin. However, DHA requires a fairly low pH and is incompatible with iron oxides, so many cosmetics manufacturers have so far struggled with the introduction of pigments, ordinary or pearlescent, for selftanning products. The solution can be to separate the pigments from DHA, placing them in separate phases of the emulsion and using pigments with extra surface modification. This makes it possible to achieve a more stable product, limiting DHA degradation.30 


source from https://www.personalcaremagazine.com