Tuesday, February 3, 2009

The much-maligned silicone

The boards at NaturallyCurly are abuzz with talk of texture, porosity, density, and elasticity. Tiffany is handling those topics beautifully, and Pittsburgh Curly and others are providing their own takes and impressions, all of which are useful and thought-provoking as always.

So, I thought I'd write about something else.

And that something else is silicones. Don't gasp. Like Jessica Rabbit, they are not evil. They are just misunderstood.

Silicones are synthetic polymers also known as polyorganosiloxanes (that's why we CGers look for ingredients ending in "cone" as well as "xane" when we read labels). The very properties that make them undesirable for those of us who follow the Curly Girl philosophy are the same properties that give them their usefulness.

Look what silicones do:

- They are heat-resistant and can protect hair from heat styling temperatures as high as 400 degrees (yes, that's Fahrenheit).
- They form a waterproof (hydrophobic) seal around hair, which is great for locking moisture in.
- They offer some resistance to sunlight, another terrific protection.
- They are flexible so all this protection doesn't come with immobility.
- Because of the seal they form, the hair looks shinier
- Supposedly, they help to eliminate frizz. I never found this to be true, but plenty of people have experienced this performance from hair products containing silicone, so to each her own.
- They help to detangle hair because of the afore-mentioned smoothing properties.

Better living through chemistry, right? Almost. Silicone molecules are too large for the hair shaft to absorb, so they sit on hair retaining moisture and keeping the sun rays at bay. At the end of the day, you have to decide whether you want your hair to breathe. If you're okay with sealing moisture in and preventing new moisture from feeding your hair, use silicones. Just know that silicones build up because they do their sealing job so well, and in most cases the solvent for removing them is sulfate (sodium lauryl sulfate and its cousins, which I will talk about in an upcoming post). Sulfates strip the hair of natural oils so when you use them to remove the silicones, you are treating your hair to some fairly harsh detergent. Only you can decide what's best for your own head. As long as you know the risks, you're a grown-up who can make her own decisions.

All silicones are not created equal, however. As this excellent post by Girl with Curl points out, science is a beautiful thing and has given us gradations of silicones. Some coat the hair quite thoroughly while others only leave a thin layer of protection on your hair. It's also worth noting that some silicones, such as cyclomethicone, evaporate fairly quickly, so if you're hoping for all-day effectiveness with that one, you might be disappointed.

Most silicones need some kind of shampoo to thoroughly remove them. The good news, though, is that only the heavy silicones require sulfate shampoos to accomplish that, and for some people, a good co-wash is all they really need. Girl with Curl addresses this in her post, and also, there is an excellent article by Curl Chemist at NaturallyCurly.com.

What about silicone on your skin?

When silicones first came out and started appearing in skin care products and foundation (especially primers), I was very dubious. It seemed to me that coating my skin in something designed to keep air out (or depending on the advertising spin, locking moisture in) couldn't possibly be healthy. And there are people who hold that point of view today (The Health Report -- about which I know nothing -- lists them as questionable). In the book What's in This Stuff? author Patricia Thomas says the following:

On the whole, silicones allow skin to breathe better than mineral oils, but question marks still hang over their long-term safety. While they increase the feel-good factor of a product, they are poorly absorbed by the skin, which raises some doubt as to how well the ingredients suspended in them will be absorbed.

And when I read now that silicone-based anti-aging creams are sought after because the silica (the basis of silicone) helps to fill in fine lines, I have to wonder whether that's healthy for skin. Maybe silicone in skin products is benign -- I just don't know enough science to say for sure. But it sounds kinda icky, doesn't it?

Paula Begoun is a fan, and certainly the industry in general has jumped on the silicone bandwagon. Silicone seems to get praise for its water-binding properties and non-greasy feel. Some forms also reflect light, making us look oh-so-beautiful. Cosmetics companies all claim that skin-care products containing silicone deliver protection yet allow skin to breathe. Which, when you think about it, seems contradictory.

So, in a nutshell, I have no answers. All I can say is that the jury is out on silicones for skin. But they sure are hard to avoid...

Sources used in this article:
Beauty Brains
Dow Corning

1 comment:

Girl with Curl said...

Thanks for the shout out. I love how the members on nc.com are so passionate about hair and can discuss it all day long with highly detailed scientific data to back them up.