Hectorite

Hectorite is an inert clay mineral used primarily as a thickener/suspending agent in low-to-moderate concentrations (often ~0.5–5%) and is generally non-reactive on intact skin. Clinical experience and patch-testing data for cosmetic clays show very low intrinsic irritancy, with problems usually limited to mechanical dryness/tightness in highly compromised barriers or when used in leave-on products that absorb lipids. Given severe-sensitivity populations, I rate it as exceptionally gentle rather than fully inert to reflect the small but real risk of barrier-drying discomfort. Safety Notes: In commercial skincare and color-cosmetic products, hectorite (often as disteardimonium hectorite or stearalkonium hectorite) is used at very low levels (~0.05–0.3%) as a suspending/thixotropic aid in low-viscosity serums, sprays, and some emulsions, especially when paired with other rheology modifiers. Typical leave-on creams/lotions, masks, and gel products more commonly sit around ~0.5–5% depending on the targeted yield value and sensory. The highest OTC consumer-available uses are seen in clay-heavy purifying masks and some makeup bases where total hectorite/clay structurant load can reach ~10–15% to build strong structure and oil/impurity adsorption; rinse-off products can tolerate the upper end more readily than elegant leave-ons.