Friday, July 10, 2009

Cetyl alcohol vs. stearic acid

I feel like the subtitle to this post should be "two go in, one comes out, it's a battle to the death!"

These two are always compared to each other because they serve the same function in lotion making - they offer co-emulsification, they increase viscosity, and they act as fatty ingredients to add to the emolliency of the lotions. But there are some differences and they're really all about the skin feel.

I think of cetyl alcohol when I want to create a thick glidy lotion, like a body butter or massage cream. I like cetyl alcohol in anything with a cationic quaternary compound. If I'm making a conditioner or using BTMS (or another conditioning emulsifier) as my primary emulsifier, then my first choice is always cetyl alcohol: It works in conjunction with the conditioning agent to impart even more conditioning!

I think of stearic acid when I want to create a thick, tenacious lotion, like a foot cream or hand lotion that will last through washing. I think it makes my thick lotions denser, creamier, and waxier. There is some drag in it, which can be a good thing when you're using a foot cream - somehow it makes it feel more intense.

Having said all of this, I think the only way to really know the difference between the two is to try them. Try this at home! Using the body butter recipe (original post, April 3) or the modified body butter recipe (original post, April 5), or your favourite lotion recipe make two batches with exactly the same ingredients, switching the cetyl alcohol and stearic acid. (Use the same fragrance as well because we want the only changes to be the cetyl and stearic.) Label your jars well so you know which is which! Ask your friends, family members, or random members of the public to try out the lotion and give their advice!

9 comments:

Anonymous said...

Thank you this helped me a lot!

Anonymous said...

Thanks, this helped me too :)

Christopher said...

I just made two small batches of hand lotion where I included cetyl alcohol in one and stearic acid in the other. I honestly didn't feel any difference between the two. As I was mixing both the batches it looked like the one with stearic acid was going to be the thickest, but to my surprise the batch with cetyl alcohol was the thickest. Both products have a silky touch to them and there's no drag as I was expecting with stearic acid.

Nessa said...

Perfect! Just what Ive been looking for! I think I am going to switch out stearic for Cetyl. Thanks Susan!!

P&C Fisher said...

Hi there, I am so glad I found this site. I love the amount of information you share with everyone.
Anyway, I just made a whipped soap recipe with stearic acid as a stabilizer/thickener and it whipped up amazingly and works fabulous, however, it seemed to leave a slight almost burning feeling on the skin and I was wondering if switching the stearic acid for cetyl alcohol would make it more mild and less burn-y...

I would appreciate any advice.
Thank you so much

Crystal

Susan Barclay-Nichols said...

Hi Crystal! I'm sorry, but I don't make soap so I can't really offer much information here. I'm wondering if the issue isn't the pH of the soap - alkaline at pH 8 or higher versus the pH of your skin at 4.7 to 5.5 or so - as opposed to the ingredients. Stearic acid is an inert ingredient that's unlikely to cause any reaction from our skin. In fact, we have it all throughout our bodies!

Israeli Krav Maga Alaska said...

Crystal - the stinging sensation you were feeling was probably unused lye in you soap. You want it to be a ph of 8-10 when complete. Also, you can't substitute cetyl alcohol for stearic acid as CA doesn't have a SAP value. Make sure you run your soap recipe through a soap calculator like www.soapcalc.net. Another way to test to make sure that your soap is completely finished if you are doing hot processed is using Phenolphthalein. The way you test it is take a little soap out when you think it's done and put it on a paper towel and and then drop a few drops of the Phenolphthalein onto the soap. If it turns purple then it's not done, it there is no purple and stays clear then the soap is done and has no lye. You can buy this stuff on Amazon and it will last you a really long time. Here is a link to the stuff I use to test my body and shave soaps. If you want to check out my store you can check it out @ www.skullbustersoaps.com.

https://www.amazon.com/gp/product/B01M07V5LA/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1#feature-bullets-btf

Kelley Spartiatis said...

I was looking for help as to whether it would be a good idea to add cetearyl alcohol to my cream soap as my superfat. I know you aren't a soaper but you know more than most of us anyway! So I wonder if you can tell me if you think it will help stabilise a whipped soap. I don't want to use stearic because I believe it can go grainy or create a drag and I want to use my cream soap as gentle face wash maybe with clay and also sugar scrub/wash for body.
Hope you can help. I don't understand the chemistry of it all!

Susan Barclay-Nichols said...

Great suggestion, Israeli Krav Maga Alaska! I love phenolphthalein!

Hi Kelley. I'm sorry, but I just don't know enough about soap to help out. Maybe one day soon as I continue to make soap and learn more?