Wednesday, June 1, 2016

One ingredient, five products: Stearic acid - conclusions and link round up

What have we learned about stearic acid this last week?

1. It's a fatty acid derived from animal or vegetable sources. (Ask your supplier if this concerns you.) It's found in almost all our butters and oils, and even in ourselves!

2. It's oil soluble, meaning you can combine it with oils and butters well, but it won't combine with water without an emulsifier.

3. It's not an emulsifier. It is an oil soluble ingredient with a required HLB of 15.

Example of a recipe done with the HLB system to create an emulsifier with stearic acid in the mix. 

4. It's a great thickener of oil-in-water lotions and oils. Use it at up to 3% in the heated oil phase to increase the viscosity of a lotion.

5. It can be used in place of the fatty alcohols like cetyl alcohol, cetearyl alcohol, or behenyl alcohol. It will thicken the product more and will have a draggier skin feel, though.

6. It's a great hardener. If you want to harden a bar, stearic acid is a great choice in place of or in addition to butters.

7. It's a great emollient. If you want some "oil free" moisturization, stearic acid fits the bill! If you want some regular moisturizing, it's pretty awesome for that purpose, too.

8. It's inexpensive. You may spent upwards of $30 a pound for a butter to thicken a lotion, while you're unlikely to spend more than $6 for 454 grams or 1 pound of stearic acid.

9. It has a long shelf life. It says two years, but you could easily have it for 3 or more.

10. It can be combined with triethanolamine to create an emulsifier for water-in-oil lotions.

Stearic acid is one of those staples I always keep in my workshop so I can make awesome creams, thicken my shampoo bars, and create solid scrub bars that keep their shape in the shower! Let's all say "yay!" for stearic acid!

For more posts on stearic acid...
Stearic acid: A few questions answered
Why include stearic acid?
Cetyl alcohol vs. stearic acid
Substituting cetyl alcohol with other ingredients in a product

The other posts in this series:

2 comments:

Bob & Angela said...

Susan,

More fun with stearic acid:

Mixing Stearic Acid with the right amount of Lye/Caustic Soda/Sodium Hydroxide in water at temperatures above 70C for about 20 minutes will produce a Sodium Stearate/Water solution, which is a great gelling agent and a decent surfactant/emulsifier.

Bob Zonis

Susan Barclay-Nichols said...

That's awesome! I can't find a place to get sodium stearate in Canada or the States, so this is such valuable informaiton.