Friday, August 13, 2010
Esters: Cetearyl ethylhexanoate
Its viscosity is 11 mPas and the surface tension is 30 mN, which means it's on par with C12-15 alkyl benzoate as a spreading ester - it's high spreading compared to our natural oils and butters, but isn't considered a great spreader in the ester world. Personally, I've found it spreads incredibly well and I'd say on a subjective level, it feels nicer than C12-15 alkyl benzoate when you're rubbing it into your skin. (C12-15 feels heavier, but when you consider that they both feel lighter than something like fractionated coconut oil, it really is a minor difference!)
Cetearyl ethylhexanoate has a high degree of water repellency, and it's about a "medium" polarity, meaning it won't act as an emulsifier or solubilizer and isn't water soluble, but it is freely miscible in other oils and fats - meaning it mixes well with our oils, butters, silicones, or other esters. It's considered to be a low occlusive ester, on par with something like sunflower oil or fractionated coconut oil.
An interesting study from Germany found that using cetearyl ethylhexanoate can help hydrate skin and prevent wounds from drying out, which prevents trans-epidermal water loss in broken skin. Normally we'd need an occlusive ingredient like cocoa butter, dimethicone, or allantoin for this purpose, but we can use something light and non-greasy feeling in that role! (So combining cetearyl ethylhexanoate with a high linoleic acid oil like sunflower or sesame or a high GLA oil like borage or evening primrose might help in retaining moisture in our skin and increasing the repair of our skin barrier! Does anyone see a potential facial moisturizer or serum recipe here?)
As with many esters, cetearyl ethylhexanoate is considered "oil free" so you can use it in products for people who might not like oils on their skin, for instance, in a facial moisturizer or serum. And it can be used in mineral make-up products to add some oils without adding oiliness. It really is a very light, very dry feeling ester with a silky kind of feeling on your skin - it's dry, but not annoyingly dry.
Why oh why isn't there some kind of shortened name for this product like cetex or cetearethex or something similar? It's not a fun name to type out every few sentences!
How to use it? You can substitute any oil in any product with cetearyl ethylhexanoate - I did that in this lotion recipe, substituting the wheat germ oil with the cetearyl ethylhexanoate to make it feel even more light and airy. And I did it in this complicated balm that feels light and less greasy than a balm that might contain an oil in its place and in this lotion bar that, again, feels lighter and less greasy than if I'd used another oil. You can add at up to 25% in any concoction to get a lighter feeling, less greasy, more easily spreadable product!
A note on this ingredient: I've found that when I use a vanilla based fragrance oil with cetearyl ethylhexanoate it gets a kind of off-putting synthetic smell to it, a high chemically note that isn't horrible but is kind of annoying. I've tried it with fragrance oils like Cream Cheese Frosting (Brambleberry) and Cake (Suds & Scents) and it just smells weird. I wouldn't suggest using a vanilla based fragrance oil with this ester, although it is worth trying it just to get an idea of the final result.
An update on this ingredient with vanilla: I've done a ton of testing of cetearyl ethylhexanoate with various fragrance oils containing vanilla, and after 2 months none of the fragrances have morphed. So I've concluded that it's safe to use vanilla based fragrances without that horrible synthetic smell. I'm blaming the cetyl esters for the morphing!
Join me tomorrow for fun formulating with cetearyl ethylhexanoate in facial products!