Ingredient Information: Lye (Sodium Hydroxide)

True soap is made through a chemical reaction called saponification.  Fats and oils (triglycerides) are mixed together with lye (sodium hydroxide) to produce soap (fatty acid salts) and glycerin.  All the added lye is consumed in the process and none remains in the finished bar of soap.

Why is lye or sodium hydroxide included in the ingredient list?

In the US, there are 2 options for soap ingredient lists: what goes "Into the Pot" and what comes "Out of the Pot".  Lye or sodium hydroxide is on The Curvy Chemist soap ingredient lists because we use the "Into the Pot" approach.

The "Into the Pot" approach lists the reactants of saponification: water, lye, fats and oils, plus any other added ingredients.  For example: Coconut oil, Beef Tallow, water, and sodium hydroxide.

The "Out of the Pot" approach lists the products of saponification: the fatty acid salts and glycerin, plus any other added ingredients.  "Coconut Oil" is saponified into "Sodium Cocoate" and "Tallow" is saponified into "Sodium Tallowate", with glycerin as a byproduct.  For example: Sodium Cocoate, Sodium Tallowate, and Glycerin. 

We try to be very open and transparent about our ingredients, and we believe that we can best communicate what is put into our soap with the "Into the Pot" approach.  We welcome questions about the ingredients we choose to use.  What ingredient would you like to learn more about next?