Wednesday, August 11, 2010
Esters: C12-15 alkyl benzoate
Like other esters, C12-15 alkyl benzoate will reduce the feeling of greasiness of other oils in your products, increases spreadability, and will solubilize other oils and silicones in an oil based product. It's also a fragrance fixative, so adding it to something like a body oil or oil based perfume spray will help the scent stick around longer! It's described as having a "silky soft after feel" and is occlusive without feeling heavy.
C12-15 alkyl benzoate is considered "oil free", so those of us who can't normally use oils on our face due to comedogenicity issues can use something like C12-15 alkyl benzoate to create oil free moisturizers and foundations (and C12-15 alkyl benzoate is considered outstanding as a mineral make-up ingredient thanks to its solubilizing abilities).
C12-15 alkyl benzoate is considered very poor on the spreadability scale, with high surface tension and low viscosity, but this is only when you compare it to other esters. If you compare it to a light oil - let's say sunflower oil - it's a very good spreading emollient. It is also high polarity, hence the ability to solubilize the other oils or silicones in a product.
You might see C12-15 alkyl benzoate under the trade names Crodamol AB or Tegosoft TN.
How can we use C12-15 alkyl benzoate in our products? As you saw in yesterday's post, we can use C12-15 alkyl benzoate as a substitute for other light oils in our products. In this cream cleanser for normal skin (or the cream cleanser for dry skin), I use C12-15 alkyl benzoate as one of the oils in the product to offer moisturizing and emolliency to the product. (And yes, I have rosacea prone, oily skin and it feels quite nice!)
Because it offers occlusion without heaviness, using C12-15 alkyl benzoate is a good way of getting the occlusive powers of something like shea butter in a lighter feeling lotion. I had planned to leave the butters out of this recipe - the trying new things out lotion - because I was in the mood for a very light, easily spreadable lotion, but the lure of my new matcha green tea butter was too much and I included it in the end. But the C12-15 alkyl benzoate would have been enough for the intended purpose - a light, spreadable lotion that offered an occlusive layer. And I used it in the complicated balm to offer a nice level of emolliency without adding a ton of weight!
Let's take a look at using esters in a basic anhydrous butter tomorrow - a whipped butter!