Bentonite is a natural clay that forms from weathering of volcanic ash. It mainly consists of silica and aluminum, but also contains various other minerals including sodium, magnesium, calcium, ferric oxide, and potassium. In cosmetics and personal care products, bentonite functions as a absorbent, viscosity increasing agent, texturizer, and suspending agent. It can be found in products such as face masks, creams, hair care products, makeup, and more.

As an absorbent, bentonite has the ability to absorb oil and other impurities from the skin. For this reason, bentonite is often used as an active ingredient in face masks intended for oily and acne prone skin. Bentonite may also be used as an inactive ingredient to increase the viscosity of a formulation. The term viscosity corresponds to the concept of “thickness”, for example, honey has a higher viscosity than water. Therefore, as a viscosity increasing agent, bentonite works to thicken formulations in order to make a product less runny and easier to spread. Bentonite also has suspending properties and is primarily used to suspend pigments in color cosmetics.