Trihydroxystearin

Trihydroxystearin is what you get when you fully hydrogenate castor oil into a waxy, fine powder.

It's mostly a behind-the-scenes texture enhancer that's especially good at "thixotropic" thing where the product stays thick but applies nicely.

Because of its structure, it also acts as a mild skin conditioning emollient that helps soften skin while preventing moisture loss.

Safety studies show it to be safe and non-irritation in clinical tests. It's typically used in concentrations up to 5%.

Since its an ester of a C18 fatty acid, it falls into the C11-24 range that Malassezia can potentially feed on. This makes it not fungal-acne safe.