Why add Stearic Acid to soap?
Stearic acid is a saturated fatty acid with an 18-carbon chain and a great ingredient to add to your soap recipes if you’d like to create an extra firm bar of soap with a light creamy-type lather.
How much Stearic Acid should I add to a soap recipe?
Stearic Acid can be used at 0.5% of your total oil weight in cold process soap (but it needs a higher temperature around 160 degrees to stay liquid under saponification).
In hot process soap, many soapers use 25-30% of the total oil weight (we have no recommendations on the amount yet, so this is the consensus we have found online).
Too much stearic acid leaves a waxy feel to the skin, but some recipes for shaving soap (link) goes up to 52% without creating any problems.
Is Stearic Acid good for the skin?
Stearic acid has been shown to protect the skin’s natural barrier against water loss and support its protective barrier.
Stearic acid is a surfactant that helps to wash away excess oil and dirt from the skin.
You can make your own Stearic Acid
Stearic Acid is made from vegetable or animal fats, but animal fats has the highest content. You can find a recipe for stearic acid derived from Tallow here.
Stearic acid in vegan soaps
If you make and sell vegan soaps, be careful with the Stearic acid. It is often derived from animal fat, so double check with your supplier.