Sodium Hydroxide - Commonly known as lye, this is what transforms our premium vegetable oils into pure natural soap. All bar soap is made with it. If you make the soap properly though, there is no active lye left in the final bar. Please don't compare our lye soap with grandma's old fashioned lye soap. Our exact scientific formulations and improved ingredients insure a milder product that's much gentler to your skin than the soaps of yesteryear.