According to this site, historically lye was made from washing rainwater through wood ashes (potash). This is clearly a survival project for another day. The resulting soap was liquid, which was fine for home use, but when bar soap became more popular, salt was added to solidify the bars, making them more marketable than bottles of soap. Salt soap, now made with sodium instead of potassium, is in bar form and the salt is used as a gentle exfoliant, giving it the name Salt Spa Soap. It is known to be good for acne and dry skin, so I figured it might be a good holiday gift for the men in the family.
It would be really interesting to solar distill ocean water at home and use the salt for soap making. The water would be probably safer than some tap waters, too.
I used 'hot process' method of preparing this soap. Most soapers use cold process with salt, because the salt makes the soap 'seize'. This is only my second time using crock pot hot process, but I love it because the lye visibly saponifies and the soap cures almost instantly. Just before the soap was at the "mashed potato" stage, I dumped all the salt in at once and stirred furiously. The salt tried settling to the bottom. Once I had it all mixed in, I glopped it into the mold. It cooled enough to turn out and cut in about half an hour. This method might not have worked well for a larger batch, and I have a huge crock pot, so be aware.
Before you start, remember what Mother always said; "Never throw salt in your eyes."
Here's the recipe.
Detergent-Free, Natural, Unscented Handmade Vegan Salt Lye Soap.
Water as a percent of oil weight 35%
Salt 80% of oil weight
For 880g of oils
Lye - 137g
Water - 334g
Coconut Oil - 704g
Olive Oil - 88g
Soybean Oil - 88g
Salt - 660g