Alumina

Irritancy: unknownComedogenicity: unknownAbrasive

The details

Alumina (aka aluminum oxide) is an inorganic mineral powder refined from bauxite that works as a quiet workhorse in a formula. It shows up often as an abrasive, absorbent, anticaking, bulking, and viscosity-controlling agent. One of its most common jobs is acting as a pigment carrier and dispersant. Alumina platelets are often blended with inorganic sunscreens like Titanium Dioxide (or with colorants) and then coated with a silicone such as Triethoxycaprylylsilane so the pigment spreads evenly and smoothly. In makeup, it can also double as a light-diffusing powder or oil absorber to keep formulas from looking greasy. The Cosmetic Ingredient Review Expert Panel has concluded alumina to be safe in present practices of use and concentration. They note it's a stable, oxidized compound and scientific research has failed to establish links to health issues. Concentrations vary depending on the product: