My shampoo bars are made with lye (sodium hydroxide) in the traditional soap making method but there is no lye left once they have cured. The lye and water cause a chemical reaction to bind with the oils in a process called saponification. This is how we make soap.
The soap then needs to cure for around 4-6 weeks after which time the soap contains no lye – only saponified oils in their hardened form.
It is not possible to make proper soap without lye. Those who claim to have soap made without lye are either referring to syndet bars (short for synthetic detergent) or ‘melt and pour’ soap which is a ready to use form of soap (originally made using lye!).