I wouldn't 'lye' to you. (Sorry, couldn't help it!) 

People are often surprised when I tell them I use lye (sodium hydroxide) to make handmade soap. They hear that word and think of a nasty, dangerous chemical. The first thing I tell them is, just as you're careful cutting vegetables with a very sharp knife or frying bacon on a hot skillet, you use the same caution when working with lye.

But what is most important to understand is that without lye you literally can't make soap. (‘Soap’ made WITHOUT lye is detergent.) Soap is the result of a chemical reaction called 'saponification' that occurs when lye (sodium hydroxide) and a triglyceride (a fat or oil) are combined to create soap and natural glycerol (glycerin). Once this chemical reaction is complete the original ingredients don't exist anymore. So, even though soap is MADE with lye, the final product itself doesn't CONTAIN lye.

It’s also important to point out that most commercial soap manufacturers actually REMOVE the glycerine (which naturally moisturizes and creates lather) from their soap and resell it to the cosmetics industry and then add in artificial moisturizers and lathering agents. All of our soap, however, contains all the wonderful, moisturizing, lathering glycerine that is created during the soapmaking process!

Below you can see the actual chemical process of saponification (thanks to my daughter, the biochemist!).