Aluminum Silicate

Aluminum silicate is an inert mineral clay/bulking and absorbent agent typically used at low-to-moderate percentages in cosmetics, and it is generally well-tolerated on skin with minimal chemical reactivity. Clinical experience and patch-test data suggest true irritant or allergic reactions are uncommon, but clay/mineral particulates can cause mild dryness or mechanical irritation in very reactive or eczematous skin, especially with frequent use or rubbing. Given that small but real sensitivity/dryness risk in compromised skin exists, it is best categorized as very gentle rather than completely inert. Safety Notes: In commercial skincare, aluminum silicate (commonly present as kaolin/bentonite-type clays or as a rheology/absorbent mineral) appears at low levels (~0.05–1%) as a suspending/thickening and oil-control aid in lotions, sunscreens, and cleansers. Mid-to-high levels (~5–20%) are typical in rinse-off masks and scrubs for absorbency and texture. The highest consumer-available levels (~25–35%) occur in clay-heavy powder masks and concentrated wash-off mud/clay masks where the mineral phase is a primary structuring/absorbing component; these are generally rinse-off rather than leave-on due to dryness/feel and slip constraints.