Tin oxide, also known as stannic oxide, is an inorganic compound with the formula SnO2. The mineral form of tin oxide is called cassiterite, and this is the main ore of tin. Tin oxide is a fine, white opaque powder. In cosmetics and personal care products, tin oxide functions as a bulking agent, opacifying agent, and abrasive. Bulking agents are used to dilute other solids or to increase the volume of a product. As an opacifying agent, tin oxide can be added to clear or transparent cosmetic formulations to render them more resistant to visible light.

Products that contain tin oxide as an abrasive will help to exfoliate the top layers of skin, removing dead skin cells, makeup, excess oil, and dirt that may have accumulated during the day. This is important because these impurities can clog pores, eventually turning into undesirable acne or other dermal-related conditions. Furthermore, exfoliating becomes even more important as we age since the skin’s natural cycle of shedding dead cells slows down. Tin oxide is considered to be a safe ingredient when used at concentrations up to 0.4% in rinse-off products and up to 1.3% in leave-on products.