Clay may be the “unsung hero” of natural skin care, according to Evan Healy, a San Diego-based aesthetician and founder of the Evan Healy personal care line, but numbers show that this natural therapy is growing in popularity. According to Schaumburg, Ill.-based market research firm SPINS, sales of natural face masks (which include commercial clay and mud products) increased 7.7 percent in conventional retailers for the year ending in June. Why the bump? “A lot of people want to make their own cosmetics, due to an increased awareness of the extra stuff in commercial products, and it’s also more cost-effective,” says Anne Nolan, customer service specialist at Cambridge Naturals store in Cambridge, Mass.

Used to cleanse and exfoliate skin, clays are rich in silica, calcium, iron, magnesium and other trace minerals that detoxify the skin and draw out impurities, according to Healy. “I tell people that if you get outbreaks when you use a clay mask, that’s a good thing; it means the clay is doing its job,” says Jocelyn Clark, a body care expert at Debra’s Natural Gourmet in Concord, Mass.

In-store merchandising and sampling presents a dilemma, though, because, as Nolan says, “You really need to take it home and give it a try.” Clarke agrees. “We often send people home with a sample from a tester jar,” she says. Debra’s also hosts a “facial night” twice a year, which helps familiarize customers with clays.

Clay is available bagged, jarred, in bulk and in prepared masks. In addition to the basic clays described below, many commercial masks mix two or more varieties in one product. Examples include Burt’s Bees Pore Refining Mask, Queen Helene Mud Pack Masque and BWC Facial Mask. Clays range in price from about $7 per pound for Aztec Secret (made from bentonite) and $10 for bulk rhassoul to $21 for commercial masks such as Zia’s French Clay Mask (1 ounce) and $28 for Ahava’s Purifying Mask (5.3 ounces).

Bentonite
Popular for facial masks and commercial facial products, bentonite is pale gray and comes from volcanic ash. Most natural deposits of pure sodium bentonite are in the western United States, primarily Wyoming, Montana, California and South Dakota. Mixed sodium/calcium bentonite (which makes a milder clay known as fuller’s earth) is mined in Greece, India and the Ukraine.

Considered one of the most powerful healing clays because of its swelling and absorption properties, bentonite’s molecular structure changes when water is added, producing an electric charge. The clay swells like a porous sponge, and the electric attraction draws out toxins from the skin and binds them to the clay, according to Clark.

French green
This popular therapeutic clay is mined in China, Wyoming, Montana and southern France. It is then sundried, crushed into a green powder and dried again to remove remaining water. The clay’s greenish color comes from iron oxides and decomposed organic matter, mostly phytonutrient-rich sea kelp and algae. It also has a high mineral content, including magnesium, calcium, potassium, manganese, phosphorus, zinc, aluminum, silicon, copper, selenium and cobalt, which all nourish skin, says Healy.

French green clay is best for toning and exfoliating the skin as well for pulling out excess oil. It draws out impurities, boosts blood flow and helps slough off dead skin cells, says Shawn Donnille, operations manager and director of quality control for Eugene, Ore.-based Mountain Rose Herbs. French green clay is mild enough to be used daily for acne treatment and is popular for spot-treating breakouts. Donnille does not recommend it for dry skin because it draws out too many oils.

Kaolin
Also called cosmetic clay, kaolin comes in red (rose clay), white (China clay) and yellow varieties. Its name derives from the province in China where it was originally mined.

Red kaolin is best suited for normal to dry skin; it gently cleanses and exfoliates while boosting circulation, Clark says. White kaolin is the mildest of all clays and is often recommended for sensitive skin to stimulate blood flow and gently cleanse. Since they don’t draw out oils from the skin, white and yellow kaolin are also suitable for dry skin. These relatively mild, multipurpose clays are often added to commercial facial masks as well as soaps and other cleansers.

Rhassoul
Found only in the Atlas Mountains in Morocco, rhassoul’s use as a beauty aid dates back to the ancient Romans and Egyptians. Rhassoul is a smectic—or swelling—clay, making it extremely absorbent. It also contains relatively high percentages of silica, magnesium, potassium, calcium and other trace minerals, which detoxify the skin by pulling out and replacing substances such as metals and unwanted oils, Donnille says.