What it is
Zinc stearate is a metallic soap formed from stearic acid and zinc, appearing as a soft, hydrophobic white powder. In sunscreens and color cosmetics it improves powder flow, adds slip and a smooth skin feel, and helps bind pressed and loose formulations. Being water-repellent and insoluble, it contributes to a dry, velvety finish in mineral and tinted products.
Safety & warnings
Zinc stearate is generally well tolerated in topical leave-on and powder products and is not a recognized fragrance allergen. As with other fine insoluble powders, inhalation of loose powder forms should be avoided during manufacture and aerosol use; this is a handling consideration rather than a concern for finished applied product.
Origin & sourcing
Synthetic; manufactured by reacting stearic acid (typically of vegetable or animal origin) with a zinc source. The stearic acid feedstock is most often derived from plant oils such as palm or coconut.
Questions everyone asks
What does zinc stearate do in a sunscreen?
It acts as a bulking and slip agent, improving powder flow and giving the formula a smooth, dry, velvety feel, and it can help bind pressed or loose powder textures.
Is zinc stearate the same as zinc oxide?
No. Zinc oxide is a mineral UV filter, while zinc stearate is a zinc soap of stearic acid used as a texture and anticaking agent and provides no sun protection.