Tin oxide refers to tin oxide (stannum (IV) oxide), also known as stannum oxydatum, a yellow-white powder insoluble in water and dilute acids and alkalis, soluble in concentrated hydrochloric and nitric acid, which occurs naturally as tartar (cassiterite).
Tin oxide is used in cosmetic formulations. It acts as an abrasive (removes plaque or impurities from the skin surface by abrasive/polishing action), swelling agent (reduces the density of cosmetic products by swelling), opacifier (reduces transparency and light transmission by clouding the product) and viscosity regulator (increases or decreases the viscosity (toughness) of cosmetic products).