Clay

Cosmetic clays (e.g., kaolin, bentonite) are used at high percentages in masks and cleansers as absorbents, and while not strong chemical irritants, they can physically dry and disrupt the stratum corneum by removing lipids and water. In sensitive or eczematous skin, this barrier stress commonly provokes tightness, stinging, and flare-ups, especially with repeated use or prolonged contact. True allergy is uncommon, but the dehydration/abrasive potential makes it a mild irritant in real-world routines. Safety Notes: In commercial skincare, clays (e.g., kaolin, bentonite, illite, montmorillonite, rhassoul) appear at very low levels (~0.1–1%) as viscosity/texture modifiers or mild oil-absorbers in cleansers and creams, and more commonly at 5–30% in rinse-off masks. The highest consumer-available products include powdered “mask” clays and clay bars sold as single-ingredient materials intended to be mixed with water/hydrosols, which are effectively 100% clay; leave-on products typically stay lower due to aesthetics, whitening, and dryness/sensory constraints.

Suitability