What it is
This ingredient is a copolymer made by reacting hydrogenated castor oil with sebacic acid to form a larger ester polymer. In formulas it is used to thicken and structure oil and emulsion phases, helping gel oils and stabilize textures. It is found in sunscreens and other leave-on products where a smooth, structured, non-greasy feel is desired.
Safety & warnings
As a large, relatively inert ester polymer, this ingredient is generally well tolerated in leave-on products. It is not a known fragrance allergen. Comedogenicity is not a typical concern for polymeric esters of this kind.
Origin & sourcing
Synthesized by polymerizing hydrogenated castor oil with sebacic acid; the starting materials can be derived from castor oil and, in the case of sebacic acid, from castor or other sources, but the copolymer itself is a processed material.
Questions everyone asks
What does this copolymer do in a sunscreen?
It works as a thickener and structuring agent, gelling oils and stabilizing the texture so the product spreads smoothly without feeling greasy.
Is it the same as plain hydrogenated castor oil?
No. It is a polymer built from hydrogenated castor oil and sebacic acid, which gives it different thickening and structuring behavior than the wax alone.