Tuesday, June 4, 2013

Stearic acid: A few questions answered

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!

And it isn't an acid in the sense that hydrochloric acid or citric acid is an acid. Yes, from a chemistry point of view it's an acid, but it won't change the pH of your product. It comes in a white pellet or flake form and feels greasy to the touch. It doesn't smell of anything that I'e noticed.

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. 

7 comments:

Anonymous said...

Stearic acid can come from some gross sources. In the second episode of the BBC documentary "welcome to india" there was a man rendering suet to sell to a stearic acid manufacturer. He bought the suet from a slaughter house and stored it outside his home rotting and covered in maggots. I'm sure this is not typical, but i am hesitant to purchase any stearic that originates from India. Maybe this is where the rumours came from

-Sara

P.S. thank you so much for all you do. I read your blog everyday!

Charbel said...

Hello Susan, I have a question, I would love if you could help me. Do you know what else I can add to a homemade deodorant that uses extra virgin coconut oil (38% of total ingredients), sodium bicarbonate (58% of total ingredients) and stearic acid (4% of total ingredients) to make it creamier? The problem I had before adding stearic acid was that it would melt in the summer, now it is kind of hard but it doesn't melt. I'm looking for another ingredient to make it creamier without having to add water... What can I do? Thanks

Izzie said...

Hello Susan, your blog is amazing :) I just found it and wow... Thanks for putting so much time in it.

Quick question about the stearic blog. You said that cetyl alcohol gives slip, and that stearic acid gives more thickness. So If I am making a foot cream, shouldn't I use more stearic? The blog seems to say otherwise, unless I am so tired from my work week.
Thanks!!!

Susan Barclay-Nichols said...

Hi Sara! Thanks for the kind words. I do my best! That's just awful! Ick!

Hi Charbel and Izzie. I've tried to answer your question in tomorrow's Weekend Wonderings. The short answer is that I wouldn't use coconut oil, and stearic acid is probably too thick an ingredient. The short answer for you Izzie is that I always recommend stearic acid for foot creams!

Judy said...

When shea butter melts on our skin does the stearic acid (part) melt or remain solid and form the occlusive layer?

aquariushearts said...

Hi
I would like some advice. I've been making creams several years but have always used beeswax as I like to make very medicinal, herbal healing creams. However, I am trying to perfect my face cream recipes and have decided I would like to use ingredients that create a more stable emulsion. I would like to try a combo of polawax and stearic acid. I would like to know what you would suggest in terms of percentages - how much to use of these in combination ?
I'll tell you what sort of texture I would like- I'd like a thick cream that "holds its shape" but not too greasy and absorbs easily for daily use. I also really enjoy a whipped like, fluffy texture. So in a nutshell... Thick but fluffy, silky not not greasy. Hehe. Hope that sort of makes sense.
I was thinking maybe 5-7-% polawax and 1-2% stearic acid?
Thank you so much for your help ! :)
Renee

Susan Barclay-Nichols said...

Hi aquariushearts! Please visit the newbie section of the blog to see my lotion making tutorials for beginners! You can modify these recipes as much as you want with stearic acid as a thickener. Try a few of those recipes and see what modifications you can make using the ingredients you have on your workshop! Have fun!!