An incredibly common scenario in the soap (opera) world:
Customer: OMG! You have lye in your soap?!? I can't use that on my delicate, sensitive, porcelain skin! It'll eat right though! It's so dangerous! Why would you ever put that on your skin? I'll just keep using Vile brand...
Soapers across the planet:
Perhaps a bit over dramatized (not much) but you get the idea.
Well there is a grain of truth to this and a huge heap of misunderstanding!
First the truth:
Yes, lye is incredibly dangerous and can actually burn through your skin when handled improperly. When making soap, I'm covered head to toe while active lye is being used, it really is NOT a joke to get on your skin.
And yes, lye is used in the production of soap. ALL SOAP. Even Vile (plus a heap of synthetic chemicals). If the product says "soap" on the label (at least in the US) lye has been used. It may or may not be on the ingredient list but it's definitely been there. Chances are also good that your pretzels and bagels have been in contact with it too, lye is incredibly useful stuff.
So where's the lie/lye?
In soapmaking, lye is not so much an ingredient as a tool no different than a bowl or spatula.
The confusion is that its actually mixed into the ingredients and then DISAPPEARS like magic.
Well, not magic but chemistry: the high pH lye interacts with the lower pH weak acids of the oils and butters and both are broken down. The end results are a "salt" and a bit of the fats used (we'll cover "superfatting" another time) the lye simply no longer exists in a properly made soap.
I'm still scared: can soap be made without lye?
Well, again there is no lye left after soap has been made. But also no, true soap requires lye. You can buy "cleansing bars" or "beauty bars" that are made of synthetic detergents that do a similar job if you're into synthetics, but these come with a whole other set of issues, including the fact that they aren't biodegradable and just sit in our waste water and environment.
So as you can see there really is no reason to be afraid of lye in a properly made, beautiful bar of soap.