This post is an attempt to clarify (via replies to this post) whether there is lye in ALL soap, AND, equally important, why it does NOT appear in the product list of ingredients (in store bought soap). i. e., why it doesn’t have to be listed since, it is claimed by its manufacturer, that the FINAL product has NONE [due to the chemical processes that occur in its manufacturing].
Lye is chemically, sodium hydroxide, and is also known as caustic soda.
I did a considerable amount of searching (via Google) and reading re the role of lye in soap. Interesting, no hits were signed off by anyone claiming to have a degree in chemistry.
But a common thread in these hits is this chemical reaction called saponification.
I copied and pasted, AND CONDENSED, the following from a website, but it is in line with what I found in other websites (the site rules for my post do not allow me to post the URL for others to see my source unless I mail it to the beemaster first--more trouble than it's worth for me to do that).
The term saponification is the name given to the chemical reaction that occurs when a vegetable oil or animal fat is mixed with a strong alkali. The products of the reaction are two: soap and glycerin. Water is also present, but it does not enter into the chemical reaction. The water is only a vehicle for the alkali, which is otherwise a dry powder.
The true fact is that modern handcrafted soap, though necessarily made with lye to get true soap, has no lye in the final product. It has all been reacted with the oils to form soap and glycerin.
Me again: from a truth in advertising perspective, it appears to me, unless contradicted by a reply from someone, that lye is ALWAYS used in soap making, and all manufacturers find it “convenient” re marketing to leave that out in the list of ingredients since, technically, there is no longer any lye in the final product, i. e., claiming that your soap is “all natural”, “organic”, etc., is going to hurt your sales if you state that lye WAS used in its manufacturing; so apparently our government's list of ingredient rules don’t require stating that.
So let's see if we can resolve this once and for all.