Safety of Dimethicone

What is Dimethicone?

Dimethicone is the basic building block of products known as “silicones”.  I talked a little about silicones in my post about amodimeithicone, which we use in Phique shampoo.  You can go back and read about that product here.  The technical name of ct is polydimethylsiloxane.  That’s a mouthful.  Dimethicone is a polymer, as you’d get from the technical name starting with “poly”.  That means it can range anywhere from two silicone atoms all the way to over a million in one chain.  When it gets that large, it is almost like a rock it’s so thick.  The picture is showing something that is a little thicker than we’d use on its own, but gives an idea about what it looks like. It’s a clear liquid.

Dimethicones come in different sizes and they are categorized by centistokes (cst).  You can read more about that here.  It just basically means the size of the molecule changes the viscosity of the dimethicone.  Typically in hair care or skin care, you use anywhere from 0.65 to 1000 cst when it’s used on its own.  There are other silicones used in emulsions that are much larger, but typically if you just see dimethicone on the label it will be in that range.

What does Dimethicone do?

Dimethicone, like amodimethicone serves two major purposes.  First, it puts a nice even coating on the hair.  Silicones tend to spread in a uniform layer on a substrate (in this case hair), which makes for easy combing.  Silicones are slick and the hair shafts can pass over one another easier.  Second, it provides shine to the hair.  I talked about that in my previous post.  They have a high refractive index, so the light reflects off them better.  I left a link on refraction on the other post but you can also see it here.  So basically it provides shine and combability.

Are Dimethicones Safe?

Silicones have been studied extensively for safety not just in cosmetics, but all other applications.  They are used in many other applications, including vinyl cleaner, car wax, personal lubricants, and breast implants.  Things that are placed in the body are well scrutinized so for topical treatment there is definitely a host of research in this area.  The CIR reported on silicone in cosmetics and you can find the report here.  Their conclusion was: “The CIR Expert Panel concluded that the following ingredients are safe in the present practices of use and concentration described in this safety assessment.”  Dimethicone was one of the silicones listed.