Clays & Salts in Skincare: A Formulator’s Guide to Natural Mineral Ingredients

Long before serums, emulsifiers, or complex skincare routines, there were simpler materials.

Earth.
Water.
Minerals.

Clays and salts are among the oldest materials used in personal care, and despite the sophistication of modern cosmetic formulation, they haven't lost their usefulness.

A simple clay can become a facial mask, cleansing powder, or creamy cleanser.

A salt can transform into a body polish, foot soak, or mineral bath.

But their simplicity can be deceptive.

Not all clays absorb the same way. Not every salt behaves the same in water. Particle size matters. Concentration matters. And an ingredient that works beautifully in a rinse-off body product may be far too aggressive for the face.

Understanding those differences allows us to use these elemental ingredients for what they do best.

What Are Cosmetic Clays?

Clays are naturally occurring mineral materials formed through the weathering and transformation of rock over long periods of time.

Different clays contain different mineral compositions and have different physical characteristics, which influence their:

• color
• texture
• absorbency
• adsorption
• swelling ability
• skin feel
• behavior when mixed with water

In skincare, clays are commonly used to absorb excess surface oil, provide gentle cleansing, add texture, and create masks and other rinse-off treatments.

Two of the most familiar cosmetic clays are kaolin and bentonite.

Although both are called clay, they don't behave the same way.

Kaolin Clay: The Gentler Clay

Kaolin is often one of the easiest clays for beginning formulators to work with.

It has a fine texture and relatively gentle oil-absorbing properties, making it useful in formulas where you want the benefits of clay without an intensely drying feel.

Kaolin can be incorporated into:

• facial masks
• powdered cleansers
• creamy cleansers
• body powders
• soaps
• scrubs

Its mild character also makes it particularly useful when clay is only one part of the formula rather than the main ingredient.

A cleanser containing a moderate amount of kaolin, for example, can feel very different from a traditional clay mask.

The ingredient hasn't changed.

The formula around it has.

Bentonite Clay: More Absorbent, More Reactive

Bentonite behaves differently.

When hydrated, certain bentonite clays swell considerably and develop a characteristic thick texture. Bentonite also has strong adsorption and absorption properties, which is one reason it is frequently used in deep-cleansing masks.

That doesn't necessarily make bentonite "better" than kaolin.

It simply makes it different.

For skin that is already dry or sensitive, a highly absorbent clay treatment may feel uncomfortable if it is used too frequently or allowed to become completely dry.

For oilier skin or targeted rinse-off products, that same absorbency may be exactly what the formulator wants.

Ingredient selection always comes back to purpose.

What Does It Mean When Clay “Draws Out Impurities”?

You'll often hear clay described as "detoxifying."

It's an appealing phrase, but it can make clay sound as though it is literally pulling toxins from the body through the skin.

That's not the most useful way to understand what is happening.

Cosmetic clays are better understood through their ability to absorb and adsorb materials at the skin's surface, including excess oil and debris.

Absorption involves material being taken into another substance.

Adsorption involves substances adhering to a surface.

Clays can exhibit both behaviors to varying degrees depending on their mineral structure.

This helps explain the clean, less-oily feeling associated with a clay treatment without requiring broad "detox" claims.

Should a Clay Mask Dry Completely?

A clay mask does not need to become hard, cracked, and uncomfortable to work.

In fact, allowing an absorbent clay mask to dry completely can leave some skin feeling unnecessarily tight and dry.

A gentler approach is to rinse while the mask is still slightly damp rather than waiting until it becomes completely rigid.

The goal is not to remove every trace of oil from the skin.

It is to cleanse without leaving the barrier feeling stripped.

That distinction becomes especially important when formulating for frequent use.

Dry Clay vs. Ready-to-Use Clay Formulations

Clay can be formulated in very different ways.

A dry clay mask or cleansing powder contains no water until the user mixes it immediately before application.

This makes preservation comparatively straightforward because microorganisms require available water to grow.

Once water enters the finished product, however, the formulation changes.

A ready-to-use clay cleanser, mask, or cream containing water requires an appropriate preservation strategy.

Adding clay doesn't preserve the water.

Adding essential oils doesn't preserve it either.

If you're creating a wet clay formulation for storage, preservation needs to be considered as part of the formula from the beginning.

Mixing Clay With Oils

Clay doesn't always have to be mixed with water.

Combining clay with botanical oils can create a softer cleansing experience and change how the clay behaves on the skin.

The oil provides:

• slip
• emollience
• reduced dry drag
• additional barrier support

while the clay contributes its characteristic cleansing and oil-absorbing properties.

This is a good example of how formulation can modify an ingredient's experience.

Instead of asking whether clay is "drying," a better question is:

How is the clay being used?

What Are Cosmetic Salts?

Salts occupy a very different role in formulation.

While clay is primarily valued for cleansing, absorbency, and texture, salts are commonly used for:

• bathing and soaking
• physical exfoliation
• texture
• mineral-based body treatments
• foot and hand soaks

Different salts also have different chemical compositions.

That means Epsom salt, magnesium chloride, sea salt, and Himalayan pink salt are not simply interchangeable versions of the same ingredient.

Epsom Salt

Despite its name, Epsom salt isn't the same substance as table salt or sea salt.

It is magnesium sulfate.

It dissolves readily in water and is most commonly associated with bath and soaking preparations.

Its crystalline structure also makes it useful in certain body products, although particle size and intended application should always be considered when using salt as a physical exfoliant.

Magnesium Chloride Flakes

Magnesium chloride is another magnesium salt commonly used in baths, foot soaks, and other water-based mineral preparations.

Although both magnesium chloride and Epsom salt contain magnesium, they are chemically different ingredients.

Their concentration, feel, and behavior in a formulation can therefore differ.

They shouldn't automatically be treated as one-to-one substitutes simply because both are described as magnesium salts.

Sea Salt & Himalayan Pink Salt

Sea salt consists primarily of sodium chloride along with varying amounts of other naturally occurring minerals.

Himalayan pink salt is also primarily sodium chloride, with its characteristic color coming from naturally occurring mineral content.

Both can be incorporated into:

• bath salts
• body scrubs
• foot soaks
• rinse-off body treatments

But when using crystalline salts directly on the skin, particle size matters considerably.

Large, coarse crystals that work beautifully in a bath may be uncomfortable or overly abrasive when rubbed directly against delicate skin.

Particle Size Matters

This is one of the simplest formulation lessons to overlook.

Two containers can hold the same ingredient while behaving completely differently on the skin simply because one is finely ground and the other is coarse.

For physical exfoliation, finer particles generally provide a gentler experience than large, irregular crystals.

The intended area matters, too.

The skin on the heels and feet can tolerate a very different physical treatment than the skin of the face.

When choosing a salt or clay, don't consider only its ingredient name.

Consider its physical form.

Salt Changes Water-Based Formulas

Salt can do more than provide exfoliation or minerals.

Dissolved salts introduce electrolytes into a formulation, and electrolytes can affect other ingredients.

Certain gums, thickeners, emulsions, and surfactant systems can behave differently when salts are introduced.

A formula that thickens beautifully without salt may become thinner—or behave differently altogether—once a significant concentration of electrolytes is added.

This becomes especially important when moving beyond simple bath products into more advanced formulations.

Never assume that because an ingredient dissolves in water, it can simply be added to any water-based formula without changing it.

Clays & Salts Aren't Interchangeable

They often appear together because both are mineral-based ingredients, but they perform very different jobs.

Think of it this way:

Clay is useful when you want absorption, cleansing, opacity, or a soft mineral texture.

Salt is useful when you want dissolution, crystalline exfoliation, or a mineral soaking experience.

And sometimes a formulation can use both.

A powdered body treatment might combine clay with finely textured salt.

A bath preparation might pair mineral salts with a small amount of clay.

The important thing is understanding why each ingredient is present.

Choosing the Right Ingredient

Before reaching for a clay or salt, start with the product you're trying to create.

For a gentle facial cleanser, a mild clay such as kaolin may make sense.

For a more absorbent rinse-off mask, bentonite may be appropriate.

For a body polish, a finely sized salt could provide physical exfoliation.

For a bath soak, Epsom salt or another bath-appropriate mineral salt may become the foundation of the formula.

Ask:

What do I want this ingredient to do?

Then consider:

• skin area
• particle size
• absorbency
• concentration
• frequency of use
• rinse-off versus leave-on application
• whether water is present
• preservation requirements
• compatibility with the rest of the formula

That's a much more useful approach than choosing an ingredient simply because it's described as "purifying" or "mineral-rich."

Simple Doesn't Mean Careless

Perhaps the greatest appeal of clays and salts is their simplicity.

A clay mask can contain only a few ingredients.

A mineral bath can be made in minutes.

But simple ingredients still deserve thoughtful formulation.

Too much clay can leave skin feeling stripped.

An overly coarse salt can be abrasive.

A wet botanical clay formula can become unsafe without adequate preservation.

A high concentration of salt can alter the stability or texture of a more complex formulation.

Natural formulation isn't about assuming an ingredient is gentle because it comes from the earth.

It's about understanding the material you're working with.

Back to the Elements

There is something satisfying about working with ingredients this fundamental.

No elaborate story is required.

Clay absorbs.

Salt dissolves.

Oil softens.

Water hydrates.

And from those simple properties, an enormous variety of skincare and body care products can be created.

Understanding clays and salts gives you another piece of the formulation puzzle—not simply a collection of ingredients to add, but materials whose texture, chemistry, and behavior you can begin to predict.

Once you understand what an ingredient contributes, simplicity becomes much more powerful.

Formulate naturally.
Create confidently.
Understand the materials behind the formula.

Published by Natural Skincare Ingredients — offering ingredient knowledge and nature-inspired guidance for thoughtful skincare and natural living.