I’ve done quite a few articles on soap making and the question always comes up: “How safe is it to be using lye?” The short answer is that if proper precautions are taken, lye is very safe to use.
Lye (Sodium Hydroxide) Basics
Tip: this is the lye we use and recommend for making soap.
What is lye?
Lye, or sodium hydroxide, is a chemical made from salt. Yep, ordinary salt. A system similar to electroplating is used to change the salt to lye.
How is sodium hydroxide made?
I watched a video on how to make it chemically, and it’s simple. Salt is dissolved in cold water to the point just before it starts to precipitate out. That is, until crystals of salt start to fall to the bottom and not dissolve. It’s important that cold water and pure salt are used, with no additives like iodine or anti-caking agents. Then the video showed graphite rods being inserted them into the salt solution and charged with electricity until crystals formed on the rods. That’s it. From there, the lye was poured into glass pans and the liquid allowed to evaporate, leaving behind the lye crystals that we buy in cans.
Lye is also made from wood ash, but that lye is inconsistent and makes a very soft bar. If you want to learn how to make lye this way, there are many tutorials available on the internet. I’ve wanted to try making Black Soap using banana leaves that is done much the same way. (See this article on banana leaves used for soap.)
How caustic is lye?
Sodium hydroxide is VERY caustic and must be used with care. It can burn holes in clothes and leave burn marks on skin. If you take care with it, you shouldn’t have any problems. I have only been burned a few times in 19 years of making soap. I was always prepared and took care of the burns right away.
Lye looks like water once it is dissolved in water, so you must take every precaution and keep it away from kids and pets. I have two dogs and a cat and they are not allowed in the room where I make soap. This saves me from the worry. You should also never stand directly over lye when mixing it with water. It will release fumes into the air for about 30 seconds. These fumes can cause a choking sensation in your throat, but are not harmful unless you inhale them directly.
What precautions can you take?
- Use gloves and eye protection when you mix lye.
- Cover your work area with newspaper, then carefully fold up and seal the used newspaper in a trash bag when you are done working.
- Keep vinegar handy. Vinegar, an acid, counteracts lye if you do get burned.
- Make soap near a water source so you can flush the affected area if needed.
- Stand back a little as you mix your lye into water, never leaning over the mixture.
- Use heat-proof containers. Some containers can crack or melt, leaving the lye to leak out.
- Wash your hands and arms when you are done making soap. It may seem like they are ok, but a single grain of lye can still produce pain and itching.
- Never leave your lye unattended, even for a minute.
How does lye work in soap?
Lye mixes with oil and saponifies, or becomes soap. At first, you have lye, water, and oil. Then the curing process begins and after a few days the lye, water, and oil is transformed into soap. At the end of the curing process, perhaps 3-4 weeks (sometimes more), there is no lye left in the soap, no oil, and no water. What is left behind is pure soap with nothing of the original ingredients left behind.
Side Note: Depending on the oil used, some components may linger, such as coconut oil compounds. For those with coconut allergies, you can make soap without coconut oil. It just won’t lather as much. Another oil to avoid is peanut oil. While peanut oil makes a wonderful hard bar of soap with nice fluffy lather, the oil still can be harmful for those with peanut allergies. On the other hand, most other nut oils are transformed enough that they can be used by those with nut allergies. The general rule of thumb is if you are not sure, don’t use it.
Questions & Misconceptions About Lye
Is there a substitute for lye in soap making?
The short answer is no. All soap is made with lye. Either sodium hydroxide is used for hard bar soap or potassium hydroxide is used for liquid soaps. There is no substitute for lye. Nothing else will make oil become soap.
I have bars of soap that don’t list lye as an ingredient. How is this possible if all soap is made with lye?
Companies are getting really good at disguising lye so that it’s not apparent on the label. It has to be in there in some form, so you might see words like sodium cocoate or sodium tallowate. These are consumer-friendly was of saying lye mixed with coconut oil or lye mixed with tallow. Other words you might see are saponified coconut oil or saponified palm oil. Same thing – these oils are mixed with lye. Remember, there is no lye in the end product.
I can only use glycerin soap because there is no lye used to make it.
Again, another way companies aren’t giving you all of the facts. Glycerin soap is made in the same exact way that hard bar soap is, it’s just taken a step further. When the soap gets to the trace stage, instead of pouring into molds, it is cooked with alcohol and sugar and made into what we know as clear glycerin soap. The lye was there in the beginning, but by the time it’s done there is no lye left in the soap.
I can’t use lye soap, it makes me itch.
While this may be true for some soaps, it won’t be for all of them, as all soaps are made with lye. The reason for itching in many cases is that the glycerin, produced in the soap making process, is removed. Glycerin is a humectant, a natural moisturizer that bonds moisture in the air to whatever it comes into contact with – in this case, your skin. If the glycerin is removed, there may be no moisturizing quality. It is not the lye causing it since it takes lye to make the oils into soap and then glycerin as a byproduct.
Glycerin is stripped out of commercial soaps since it is a valuable commodity and sold to fertilizer and explosives companies. Hence, nitro glycerin. If you ever see glycerin as an ingredient in soap, be skeptical. It usually means that the naturally occurring glycerin has been removed and a tiny amount has been added back in. More likely than not, it’s not enough for adequate moisturizing. The same could possibly be true for those with fragrance sensitivities. It may not be the fragrance that irritates, but rather, the lack of adequate glycerin.
I hope I’ve dispelled many of the common fears about lye. Don’t be afraid to use it, just be sure to treat it properly.
How about you?
Have you used lye in soap making? How did it go?