What it is
Decamethyltetrasiloxane is a low-molecular-weight linear silicone fluid that is volatile and evaporates after application. In sun care it acts as a lightweight emollient and carrier solvent, helping a product spread easily and leave a smooth, non-greasy, dry finish. It is often used to improve the sensory feel of mineral and high-SPF formulas.
Safety & warnings
Volatile silicones of this type are generally well tolerated and are considered low risk for irritation and sensitization in topical cosmetic use. They are non-comedogenic for most users.
Origin & sourcing
Synthetic. It is a manufactured volatile silicone (siloxane) fluid.
Questions everyone asks
What does decamethyltetrasiloxane do in sunscreen?
It is a volatile silicone that thins the formula, helps it spread smoothly, and leaves a light, dry, non-greasy finish before evaporating.
Is it greasy on skin?
No, it is a fast-evaporating silicone fluid that contributes a dry, smooth feel rather than a heavy or oily one.