Alumina
Alumina (Aluminum Oxide, Al2O3) is a multi-functional helper ingredient used primarily as a pigment carrier for inorganic sunscreens (e.g., titanium dioxide) and colorants, often blended with alumina platelets and coated with silicone to enable even dispersion and application. It also functions as an absorbent/mattifier, viscosity controlling agent, and opacifying agent. Additionally, it is used as an abrasive in microdermabrasion and scrub formulations. Its CosIng-listed functions include abrasive, absorbent, anticaking, bulking, opacifying, and viscosity controlling.
Alumina helps pigments (including mineral sunscreen actives) disperse evenly in formulas and spread smoothly on skin. As an absorbent, it can reduce shine and mattify the skin's appearance. In scrub and microdermabrasion products, it provides physical exfoliation to resurface the skin.
No specific cautions or contraindications are mentioned in the source.
