All handmade soap or cold process bars are made with Lye. Soap is made by reacting fats and oils with lye. Lye is also known as caustic, caustic soda or sodium hydroxide. Tue soap is created through the saponification process with involves combining oils and fats with the lye. Made just like the old days. It needs to cure for 6-8 weeks, depending on the temperature and humidity. What .