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Industry expert Tony O'Lenick explores: What is the difference between a cyclic silicone and a volatile silicone?
Silicone can exist in one of three types of structures: ring-like circular structures, straight chain silicone structures, and cross-linked silicone structures. Silicones can also be volatile or nonvolatile. Much confusion exists in the cosmetic industry because cyclomethicone (D4–D6) is both cyclic and volatile. This often leads to confusion in terminology.
A cyclic silicone refers to a structure of a compound that possesses a cyclical structure rather than the chain structures of dimethyl silicones. A cyclic silicone can be represented by the following structure:

If n = 4, the product is D4 (octamethylcyclotetrasiloxane ); if n = 5, decamethylcyclo-pentasiloxane. These are volatile. Higher values are nonvolatile. In fact, cyclic resins have recently been introduced.1