What it is
PEG-30 Dipolyhydroxystearate is a polymeric emulsifier made by esterifying polyethylene glycol with polyhydroxystearic acid, giving it both water-loving and oil-loving regions. It is a workhorse emulsifier for water-in-oil systems, helping to disperse the water phase finely and keep the emulsion stable over time. It is frequently used in sunscreens and rich creams that benefit from a robust water-in-oil base.
Safety & warnings
PEG ester emulsifiers of this type are generally well tolerated and considered non-irritating at cosmetic use levels. It is not a fragrance allergen. It is not notably associated with comedogenicity, though sensitive users may prefer to patch test.
Origin & sourcing
Synthetic; produced by reacting polyethylene glycol with polyhydroxystearic acid (the latter derived from hydroxystearic fatty acid).
Questions everyone asks
What does PEG-30 dipolyhydroxystearate do?
It is an emulsifier that stabilizes water-in-oil formulas by keeping the water phase finely and evenly dispersed.
Why is it used in sunscreens?
Many sunscreens use water-in-oil bases for a robust feel, and this emulsifier helps build and stabilize that type of formula.