The type of silicone used in hair is not exactly like that solid though it still does not evaporate. It behaves like an oil and is sometimes referred to as silicone oil.
Here is the dish on dimethicone:
|What is it?||A silicone.
|Where is it derived from?||Chemically synthesised|
|Does it evaporate?||No|
|Is it water soluble?||No. It can be rubbed off to a very small extent but in general water is not sufficient to clean it off.|
|Do you have to use a sulphate (SLS) shampoo to clean it off?||SLS containing shampoo is the ideal for good removal. However, other milder sulphate free surfactants can slow or stop silicone build up.|
ACTION IN HAIR CONDITIONER
|What does silicone do in shampoo and conditioner?||It is added in as a conditioner|
|How much dimethicone is added?||Varies greatly. 3-5% is around the mark for most rinse out conditioners and shampoos. Leave in conditioners can be in the same range but can equally go as high up as 80-90% for serums.|
|Is dimethicone a major component of shampoo or hair conditioner||No it is not for shampoo. It varies greatly in conditioner but is generally within (or just outside) the first 5 ingredients after water.|
ACTION ON HAIR
|Does dimethicone do anything to hair itself||1. It adsorbs (sticks on) on to the outer cuticle of hair.
2. It forms a film on the hair which smoothes down the cuticle
3. It lubricates the hair and is thought to contribute to easier wet combing (i.e less friction).
4.In hair serum, for thermal processing, dimethicone is a heat protectant
|Does dimethicone penetrate hair?||It is not known to. It has no charge and tends to form a film outside hair rather than penetrate.|
|Does dimethicone prevent hair from absorbing water?||In shampoo and rinse out conditioners, it is actually considered a permeable water barrier. Which means it is a barrier to water but it does not fully prevent water entry and exit.|
J Soc Cosmet Chem, pp 275-284, 1992
J Soc Cosmet Chem, pp 131-136 , 2001
J Soc Cosmet Chem, pp 135-148, 1994
J Investig Dermatol Symp Proc 10:201 –204, 2005