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Aluminum Stearate

What Aluminum Stearate is & what it does

A metallic soap used to thicken oils, suspend pigments, and give a smooth feel. It helps stabilize and structure formulas.

What is Aluminum Stearate and what does it do in sunscreen?

Aluminum Stearate is a metallic soap, made from aluminum and stearic acid (a fatty acid). In sunscreen it thickens oils, helps suspend and coat pigments, and gives a smooth, even feel. In mineral formulas it is often used to coat zinc oxide or titanium dioxide particles so they disperse evenly and resist clumping. It mainly works on the texture and stability of the product.

Is Aluminum Stearate safe?

Yes. Aluminum Stearate is used in small amounts as a thickener and pigment coating, and it stays on the surface of the skin rather than being absorbed in any meaningful way. It is well established in cosmetics and is not considered irritating for most people at the levels used. The aluminum here is bound up in an inert soap, which behaves very differently from soluble aluminum salts.

Does Aluminum Stearate clog pores?

Generally no. It is not flagged as comedogenic and is used in small amounts mainly to structure the formula and coat pigments. As with most texture agents, if you are prone to breakouts the heavier oils and waxes in a product are a more likely cause than a metallic soap used in trace amounts.

What else is Aluminum Stearate called?

Aluminum Stearate is the INCI name on the label. Chemically it is the aluminum salt of stearic acid, which is why it is described as a metallic soap. You may see related metal stearates like magnesium stearate or zinc stearate used for the same texturizing and pigment-coating purpose.

Is Aluminum Stearate a preservative?

No. Aluminum Stearate is a thickener and pigment dispersant, not a preservative. It does nothing to stop microbes from growing in a formula. The preserving in a sunscreen is handled by ingredients like phenoxyethanol, the glycols, or ethylhexylglycerin, while Aluminum Stearate only affects texture and stability.

Sunscreens with Aluminum Stearate

We rate 251 sunscreens that contain it, showing the top 10 by overall score:

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