3.03.2008

The Lowdown on Lye

I've often received the question, "Does your soap have lye in it?" from potential customers who worry that soap made with lye may be harsh and unpleasant to the skin. In the past, lye was made from wood ash and the strength of the solution was variable, so that the soap maker could not measure precisely how much to use. Grandma's lye soap was remembered by generations as being awfully harsh. Now of course we can measure quite precisely, and research has been done to determine exactly how much lye it takes to saponify each unit of every type of fat a soap maker might use.

So what was that word, saponify? That is what happens when you mix a fat or oil with an alkali or 'base'.(lye is an alkali). As explained at Wikipedia: "The fats and the bases are hydrolyzed by water; the free glycerol heads bond with the free hydroxyl groups to form glycerin and the free sodium molecules bond with the fatty acid tails to form soap".

Huh? All that means is the chemical reaction breaks up all the molecules of the lye and oils, and they go back together in different formations. The newly formed substances are glycerin and soap. No soap can be made without an alkali like lye, and no lye is left in properly made soap - it has all been used up creating the soap and glycerin molecules.

So no, there is no lye in my soap. :)

7 comments:

Rosebud Collection said...

I made soap once..kind of fun.
You did a wonderful job explaining all about it. Thanks.

Joanna Schmidt said...

Very nice explanation. Lovin the soapies btw. They are just gorgeous!!!

sherrieg said...

You summed it up perfectly and succinctly! Would you allow me to post this on my blog as well, with full credit to you, of course? :) Thanks!

savonara said...

Thanks - I had a little help from good ole wikipedia so I edited to reflect the source. Feel free to share!

sherrieg said...

Thanks so much! :)

Helen said...

Your soaps are so pretty. I would never attempt to make soap myself. I'd be afraid it would turn out like my cooking.

I can only use unscented soaps and that leaves me few choices.

Rosalie said...

Ahhhh...the science behind soap. I had no idea!