What it is
Dimethicone is a silicone polymer, polydimethylsiloxane, built from repeating siloxane units and represented by the formula CH3[Si(CH3)2O]nSi(CH3)3. It is optically clear, inert, and hydrophobic, and behaves as a viscoelastic fluid. In skincare it works as an emollient and protective agent, smoothing the skin surface and lending the silky, slip feel typical of modern sunscreens and primers. It is also widely used in hair conditioners and as an anti-foaming agent in other applications.
Safety & warnings
Dimethicone is widely regarded as well tolerated and gentle. The Cosmetic Ingredient Review panel concluded that dimethicone and related polymers are safe as used in cosmetic formulations. It is chemically inert and sits on the skin surface as a light film, which is why it is common in products aimed at sensitive skin; it is the same material classified as food additive E900 in Europe.
Origin & sourcing
Dimethicone is a synthetic silicone made from silicon-based starting materials. The classic route treats dimethyldichlorosilane with water, releasing hydrochloric acid, while commercial production commonly uses ring-opening polymerization of cyclic siloxanes with a base catalyst to control chain length.
History
The term silicone was coined by chemist F. S. Kipping in 1901. The commercial silicone industry was launched in the 1930s by James Franklin Hyde, often called the father of silicones, whose work led to the founding of Dow Corning, a venture between Dow Chemical and Corning Glass Works dedicated to silicone production.
Questions everyone asks
Why does dimethicone make sunscreen feel silky?
It is a silicone polymer that spreads into a smooth, slippery film on the skin, giving the elegant slip and matte feel common in modern sunscreens.
Is dimethicone bad for the skin?
It is chemically inert and the Cosmetic Ingredient Review panel concluded it is safe as used in cosmetics; it sits on the surface as a light, breathable film.
What is dimethicone made from?
It is a synthetic silicone made from silicon-based raw materials, produced by polymerizing siloxane units into a clear polymer.