Also known as sodium borate decahydrate, borax is a mineral composed of sodium, boron, oxygen, and water. It has fungicide, preservative, insecticide, herbicide, and disinfectant properties. Borax functions as a bleaching agent by converting some water molecules into hydrogen peroxide (H2O2), which generates free-radical damage and is a problem for skin. The pH range of borax is about 9 to 11; therefore, it can be a significant skin irritant when used in cosmetics.