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Common Name(s): Montmorillonite,volcanic ash clay,swelling clay

CAS Number: 1302-78-9

DESCRIPTION

What It Does: Provides thixotropic clay gellation and deep oil absorption from swelling smectite clay.

Why It's Used: Strongest adsorbing clay for deep cleansing masks โ€“ bentonite's high cation exchange capacity and swelling capacity provide the deepest oil and toxin adsorption of common cosmetic clays.

How It Works: Montmorillonite 2:1 layered silicate swells up to 15ร— in water via interlayer water absorption. very high cation exchange capacity (cec: 80-150 meq/100g) provides exceptional adsorption of cations, oils, and toxins. thixotropic gel provides 'mask that hardens' sensory experience.

Typically Found In: Clay masks,deep cleansing products,detoxifying formulas

TECHNICAL DETAILS

Primary Category: Functional ingredient โ€“ swelling clay mineral

Secondary Functions: Skin conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 1%โ€“25%

SOURCING & ETHICS

Vegan Status: Conditional - supplier confirmation required

Halal Status: Unverified - supplier confirmation required

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier. [audit 2026-07-29 rev2: the record's own source_notes does not assert a non-animal origin, or instructs the reader to verify with the supplier; "yes" asserts knowledge the record does not hold. determination requires shariah-panel sign-off.]

SKIN COMPATIBILITY

Irritancy Rating: 1/5 โ€“ very low

Comedogenicity Rating: 0/5 โ€“ non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1โ€“2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Bentonite's extraordinary swelling (up to 15ร— dry volume) arises from its 2:1 layer structure: sodium bentonite's inter-layer sodium cations attract very thick water shells, forcing the silicate layers apart by electrostatic repulsion. calcium bentonite swells only 2-3ร— by comparison, explaining why sodium-exchanged bentonite is the industrial standard for swelling applications.

Last Verified: 2026-03-12

Primary Sources: Cosing database,cir safety assessment