What it is
Aluminum/magnesium hydroxide stearate is a complex metallic stearate that acts as a gellant and suspending agent in oil-based and anhydrous systems. In sunscreens it helps thicken the oil phase, keep pigments and mineral filters such as titanium dioxide or zinc oxide evenly dispersed, and prevent settling. It contributes to a stable, uniform product texture.
Safety & warnings
This metal stearate is used as a structuring agent and is generally well tolerated, with no significant allergen concerns at cosmetic use levels.
Origin & sourcing
Synthetic; produced by reacting aluminum and magnesium sources with stearic acid to form a mixed metal soap.
Questions everyone asks
What is the purpose of this ingredient in sunscreen?
It thickens the oil phase and keeps mineral filters and pigments evenly suspended so the product stays uniform.
Is it a sunscreen active?
No; it is a texture and suspension agent, not a UV filter.