Yes…and no. Lye is a mandatory ingredient in soap. Without it, you would have a detergent instead of soap that is safe for the skin. Lye can be a scary ingredient – it can burn! But once it is blended with the oils and water, a chemical reaction occurs between the lye and fatty acids in the oils. This chemical reaction creates an entirely new substance – soap! Lye, as it was when it was added into the batter, is no longer present.