Molecular representation of decamethylcyclopentasiloxane, shown as tubes with surrounding wire surface. Atoms are colour-coded: Silicon (blue), oxygen (red), carbon (grey), hydrogen (light grey). This is an organosilicon compound with the formula ((CH3)2SiO)5. It is a colorless and odorless liquid that is slightly volatile. The compound is classified as a cyclomethicone. Such fluids are commonly used in cosmetics, such as deodorants, sunblocks, hair sprays and skin care products. Decamethylcyclopentasiloxane belongs to the functional group of siloxane in organosilicon chemistry with the Si-O-Si linkage. A new application of siloxane is a "second skin" polymer assembled into a network arrangement known as cross-linked polymer layer (XPL). This can be used to protect and control skin properties for medical and cosmetic applications.