Whether by habit or just personal preference, most people prefer their liquid soap to be clear. Soap makers pride themselves on just how crystal clear their liquid soap is.
In bar soaps, a little bit of extra oil (superfatting) is a good thing. It's insurance against too much lye in the soap, and the extra oil is good for your skin. Technically the same thing holds true for liquid soap...except that the extra oil in the soap causes cloudiness and can separate, causing a white, gooey layer floating on the top of the soap.
Not a good thing.
In order to get the clearest soap possible, liquid soap is usually formulated using either a 0% lye discount (superfat) or even with a lye excess. The excess lye needs to be neutralized to make the soap milder on your skin. The soap making method you are using will determine the neutralization method you should use.
The Catharine Failor Method
Most people get started making liquid soap using the Catharine Failor method in Making Natural Liquid Soaps. The process works perfectly well, but some soap makers are confused by the way that her recipes all include a lye excess that must be neutralized. To neutralize liquid soap made using a Failor recipe:
- Make either a 20% boric acid solution or a 33% borax (20 Mule Team) solution.
- For the boric acid solution, take 8 oz. of boiling water and add 2 oz. boric acid. For the borax solution, use 3 oz. borax in 6 oz. of boiling water. It's important to stir very well and make sure that it stays very hot. As this mixture cools, the borax or boric acid will start to precipitate out of the mixture - and it won't mix into your soap!
- Add about 3/4 oz. of neutralizer for every pound of soap paste (just the paste, not the added water.) So, for the recipe which we made in Traditional Liquid Soap, which makes about 2.8 lb of paste, we add 2 oz. (2.13 rounded down to 2) of neutralizer solution. (Too much neutralizer (especially the boric acid solution) can cause cloudiness, so it's best to round down and/or err on the conservative side.)
- Slowly pour the neutralizer into the re-heated soap mixture and stir well. Add one ounce first and let it sit for a bit. Then add another half ounce. Then, if you still have no cloudiness, add the final half ounce.
The Summer Bee Meadow Method
The folks at Summer Bee Meadow have become the experts on liquid soap making. The big difference is that their recipes are not calculated with a lye excess, but rather with a 0% lye discount. But even with no lye excess, you still need a bit of neutralization. To neutralize using the Summer Bee Meadow method:
- Make a 5% solution of either boric acid or borax:
- .5 oz. boric acid OR borax
- 9.5 oz. nearly boiling distilled water
- To hot soap paste, add 4 tbs. of your neutralizing solution per 8 oz. of soap paste. (For 1 lb. of soap paste, add 8 tbs. For 2 lbs. of soap paste, add 16 tbs. of neutralizer. Etc.)
- To be extra safe, test your liquid soap with Phenolphthalein pH Indicator.
After you've neutralized the soap, dilute and sequester the soap as you normally would. Using either method, the neutralization gives you nice clear soap that is still mild to the skin.