Cosmetic grade silicones have a molecule size that is too large to enter or clog a human pore. Silicone fluids are considered “breathable” because these large molecules have wide spaces between them, which allow other ingredients and air to penetrate. The most basic silicone in cosmetics is Dimethicone. It is a clear, non-reactive, liquid product that can range in thickness, depending on the length of its polymer backbone, from watery thin to taffy thick. Cyclomethicone is a shorter cyclic molecule which has many of the same properties of dimethicone except that it evaporates while dimethicone does not. Dimethicone copolyol is a silicone which contains an -OH group which makes it more soluble in water. This makes it easier to incorporate into water-based formulations but also reduces the usefulness of the silicone.