Kaolin, Bentonite, Rhassoul and Friends: A Friendly Guide to Cosmetic Clays

15 October 2026 · MakeYourSkin Team

Illustration of five small bowls of clay powder in white, grey, green, brown and pink with a wooden spoon and mask brush — MakeYourSkin Journal

Clay is probably the oldest skincare ingredient there is. People have been smearing mud on themselves for thousands of years, and for good reason: clay soaks up oil, lifts away grime and leaves skin feeling clean and soft. But a jar of white kaolin and a jar of grey bentonite behave very differently. Here's your field guide.

The science in one paragraph

Clays are made of tiny layered minerals. Some, like kaolin, carry almost no electrical charge, so they're soft, gentle and lubricating. Others, the smectites (bentonite, montmorillonite), swell with water and can swap ions, which makes them strongly absorbent (Viseras et al., Clays and Clay Minerals, 2021). One study measured bentonite's ion-exchange capacity at about 100 meq/100 g, versus roughly 11–15 for kaolins (Iannuccelli et al., 2016). In short: kaolin is gentle, smectites are thirsty.

Meet the clays

  • Kaolin (white clay): the gentlest. Soft, non-swelling and great for dry, sensitive or mature skin. Also a lovely base for powders and dry shampoo. Kaolin Clay, White is the bright mask grade.
  • Pink Clay: typically a gentle blend, a pretty middle ground for normal skin.
  • French Green Clay: mainly illite with iron-rich smectite (USGS). A classic for oily, congested skin.
  • Rhassoul Clay: a Moroccan clay made mostly of stevensite, a magnesium-rich smectite (Benhammou et al., 2009). Famously silky and used for centuries as a hair and body wash in hammam rituals.
  • Multani Mitti (Fuller's Earth): strongly oil- and grease-absorbing. It got its English name from cleaning raw wool (Britannica). The Indian go-to for very oily skin, often in an ubtan.
  • Bentonite and Montmorillonite: the thirstiest. Powerful in small doses in masks, and also used at low levels as thickeners and suspending agents in lotions (see the bentonite entry).
  • Bonus, not a clay: Activated Charcoal adds dramatic colour and extra absorbency to "detox" masks.

Quick chooser

  • Dry or sensitive: kaolin, or kaolin plus a little pink clay.
  • Normal or combination: pink or rhassoul.
  • Oily or congested: French green or multani mitti, softened with some kaolin.
  • Very oily, resilient skin: a touch of bentonite in a kaolin base.
  • Hair and body wash: rhassoul.

The mistake almost everyone makes

Letting the mask dry until it cracks. Dermatologists quoted by Stylist explain that a fully dried clay mask starts drawing moisture from your skin barrier, so rinse it off before it dries completely (Stylist). Aim for 5–10 minutes, while it's still slightly tacky.

Make a better clay mask

  1. Mix clay with a hydrosol or distilled water to a smooth, yoghurt-like paste.
  2. Add a humectant like Glycerin (a few drops per spoonful) to slow drying.
  3. Optional extras: Colloidal Oatmeal for comfort, Aloe Vera Juice for a cooling feel.
  4. Apply, wait 5–10 minutes, rinse with warm water and moisturise.

For brands: quality matters

Clays are natural earth materials, so their microbial load and heavy-metal content vary by deposit. Researchers studying clays for skin use stress testing them against microbial limits and checking heavy metals (Lampropoulou et al., Applied Sciences, 2023). Always request the Certificate of Analysis (we include one with every batch). If you sell a pre-mixed wet mask, it also needs a proper preservative system.

Browse Clays & Mask Bases and Purifying Agents.