It’s come up again this morning. I haven’t even had a full cup of coffee yet, and yet in one of my Facebook groups, someone is frantic because they tried to make soap without lye and now they have a mold full of oils that’s doing nothing. In this case, the victim tried shredding a bar of African Black soap instead of using lye. To seasoned soap makers, this will seem comical, incredulous. To you newbies, you might be wondering what she did wrong, and I will tell you.
You can’t make soap without lye. By definition, soap is the result of the chemical reaction between fats and caustic acids (lye) such as NaOH or sodium hydroxide, what we commonly use, or KOH or potassium hydroxide; what we use for liquid soap and occasionally in conjunction with NaOH in solid soaps. There’s other caustic acids; potassium carbonate, etc., some of which are used to make soaps such as African Black Soap. So while sodium hydroxide is the chemical most commonly referred to as lye, it’s not the only one.
You take your lye and water you’ve mixed it with, you mix it in with your oils and butters, and a chemical reaction called saponification happens. It takes about 24 hours to complete. At the end, you don’t have water, lye, or oil or butters: you have soap. You have the saponified salts of the oils, such as sodium cocoate (coconut oil), sodium tallowate (tallow), sodium olivate (olive oil), and so on. So when someone asks me if I use lye in my soap, I say yes, and I explain this process. And when they ask me if my soaps contain lye, I say, “Not after they are cured!” and I explain this process.
Now, every fat requires a specific amount of lye to get through saponification. 500g of olive oil requires 67.7g of lye, while 500g of lard requires 70.5g. When you are making soap the idea is to always use more fat than the lye can conver into soap. This prevents the presence of any excess lye in the finished product. 5-10% superfatting is the usual, with 20% typical on 100% coconut oil soaps. So, remember, superfatting protects against excess lye in the soap being irritating.
We cure soap for 4-6 weeks for two reasons. First, it allows excess moisture from the bar to evaporate and the bar to harden. This makes a good, hard, bar of soap that won’t disintegrate the first time someone forgets and leaves it in the shower. Second, the pH of the bar will drop a little over those weeks, resulting in a milder bar.
But what about melt and pour soap? I don’t have to use lye there!
Well, actually, that’s because someone already did. If you read the ingredients on those bases, it’s going to say “sodium hydroxide” somewhere. So the lye is there, it’s just already been dealt with.
You’ve probably believed that if you get the tiniest speck of lye on you it will burn a hole in your arm the size of a baseball. Not true. This isn’t Fight Club. Yes, lye is a dangerous chemical and a caustic substance -much like bleach-but just show a little respect. Wear gloves and long sleeves. Definitely wear safety glasses. If you get a bit of lye water or raw soap on you, calmly wash it off with soap and water. You might not even notice for a few minutes until it starts itching.
Now. I hope I’ve covered why you can’t make soap without lye and maybe put some fears to bed about lye so more people will make soap. It’s fun and easy and you should try it.