In this post on stearic acid, Louise asks: I hate the idea of anything "unnatural" in a skin or face cream.
Stearic acid is natural. (It's also known as octodecanoic acid.) It's one of the things that makes our butters stiffer than oils - look at cocoa butter, mango butter, shea butter, or other butters - and it's found in every animal, including us. Stearic acid isn't necessarily derived from animal products. If this concerns you, check with your supplier about the origin.
The one I buy from Voyageur Soap & Candle is of vegetable origin. I checked a few other retailers, and they all said vegetable origin, so I don't think it's much of an issue!
Why do we find it in our products? As I mentioned above, we find it in our butters, and it's one of the reasons that we can whip butters and not whip oils. The stearic acid thickens and stabilizes the fats. We can add it to our lotions as a thickener or a stiffener in products like lotion bars, shampoo bars, conditioner bars, and other bars. It acts as an oil free emollient in many products. And it can make candles harder and longer lasting.
In a lotion, Sarah coined the idea that "Cetyl (alcohol) is slick, while stearic (acid) is thick!" When you're making a product like a foot or elbow lotion, try substituting the stearic acid for the cetyl alcohol to make a much thicker feeling product that stays on longer!
As an aside, there's a weird thing going on where a multilevel marketing company that eschews preservatives despite all the recalls they've had is claiming that certain ingredients, like glycerin or stearic acid, are being derived from road kill. Think about this seriously for a minute. Why would any company pay someone to drive around collecting road kill when there's so much stearic acid available in animal fats? With the price of gas these days, it makes no sense to troll the roads for the off chance a raccoon or possum met with a horrible fate! Silliness.