For anyone who makes soap, this whole entry will be fairly redundant. However, I’ve been getting a lot of questions lately from people who say they are scared of lye, and want to know how to make soap without lye. They’re either afraid of working with it, or they think it will make a bar of soap that will be highly irritating/dangerous. I’m going to address both of these concerns, and hopefully I’ll be able to talk you into making your very own soap—with lye!
First off, I want to give you a brief overview on exactly what soap is. Soap is an alkali (like sodium hydroxide or potassium hydroxide) combined with fats. Together they go through a reaction called “saponification”, and in the end you are left with soap. So, by the very definition of “soap”, you cannot make soap without lye. That is like trying to make a baking soda and vinegar volcano without the vinegar. No vinegar and you’ve just got a pile of baking soda. No lye, and you’ve just got a bucket of fat.
Now, every fat requires a certain amount of lye to turn it into soap. 500g of olive oil requires 67.7g of lye, whereas 500g of lard requires 70.5g of lye. When you are making soap the idea is to always use more fat than the lye can convert into soap. This prevents the presence of any excess lye in the finished bar, which means it will be a nice, gentle bar, and will not be irritating. A 5% superfat is fairly standard (you don’t want to go much higher than 10% or the bar will be very soft and can go rancid). With a 5% superfat, you would only use 64.3g of lye for 500g of olive oil instead of 67.7g. That means 5% of that 500g of olive oil will not be turned into soap, giving you a bar of soap that is 475g of saponified olive oil with 25g of leftover olive oil mixed into the bar to moisturize your skin and work as a buffer against any errors in measuring the lye.
So, superfatting protects against excess lye in the soap being irritating. It is worth noting that every bar of proper soap you’ve ever used in your life has been made with lye, so if those were fine, yours will be as well.
If you’ve never worked with lye, but you are afraid of working with it, I don’t blame you. You’ve probably done a bunch of research, just like I did, and it’s all convinced you that if you get the tiniest speck of lye on you it will immediately burn a hole in your arm the size of a softball. That is not true at all, so relax.
Yes, lye is a caustic substance and you definitely shouldn’t drink it or take a bath in it. But, really, it’s not any worse than bleach or ammonia. Respect it and all will be well. Wear gloves and clothes you don’t care about, wear goggles, lay newspapers down on your work station, and be careful. Work slowly, keep your temperatures low, and don’t leave your lye water unattended for pets or children to get into. Really, that’s it. You’ll be fine. If you get a wee bit of lye water or raw soap splashed on you, it’s not a big deal at all—just wash it off with running water for a few minutes. You probably won’t even notice for a minute or two, at which point it’ll start to itch a little bit. Seriously, that’s it—just a bit of itching. No burning, no horrible scarring, no big deal. Using vinegar is specifically not recommended as it will make it worse.
Some people think that using a melt & pour soap base is a good way to get around using lye. While this is true, 1) the M&P soap was made with lye by somebody else, so it was still involved in the process, and 2) M&P bases often have dodgy ingredients in them, like sodium lauryl sulfate (known to be irritating) and palm oil (which is pretty terrible for the environment), so if you’re worried about irritation, making your own soap is the best way to go. They’re also grossly marked up.
The only way you can get a “soap” without using lye is to add a surfactant like sodium lauryl sulfate to water. Surfactants create lather, and are pretty cool—you can add them to pretty much anything to create a lathery version of it (bath bombs, bath salts, clay scrubs, etc.).
There are tons of different surfactants, and you can get gentle ones. If you are really concerned about lye, surfactants may be a good alternative for you—but you still aren’t making soap! A lathering bar made from surfactants is called a “syndet bar”—”synthetic detergent bar”. They are, by definition, not soap—there’s no base, and no saponified fats.
Hopefully that helps ease any worries you’ve had about soap making and explain why you need the lye (and why it’s really not scary at all)! If you’ve got any questions, stories, or tips, feel free to share them below 🙂
Want to get started?
- Learn to Make Soap
- Learn Why I Use Lard & Tallow in my Soap (and why you should, too)
- Make a batch of my all-in-one soap
- Check out all my other cool soap recipes!