The Truth about Lye

When people see all the protective gear I don in preparation for making a batch of soap, I am often asked a lot of questions. Why would I want to use your soap if you are using ingredients that might burn your skin during the soap-making process? Why are you using caustic chemicals in "natural" soap? What the heck is lye anyway?

Well, my friends, I am here to help set the records straight. You cannot make a bar of soap without using lye (otherwise knows as sodium hydroxide) as an ingredient. The saponification process (or the process in which oils emulsify with lye to become a solid mass—soap!) could not occur without this key ingredient. Once this chemical process occurs, both the lye and the oils/fats are changed. You no longer have a caustic solution (lye water) and oils. You have soap. And once saponification is complete, and your bars of soap have gone through their curing process (typically, four to six weeks) all remaining traces of lye disappear.

Back in the day, soapmakers made their own lye, which was made from wood ashes and water, also called potash. In fact, there is one Roman legend that claims soap was named after an ancient site where animal sacrifices took place, Mount Sapo. After an animal sacrifice, rain would wash away the animal fat and ash that collected under the ceremonial altars, and it would run down to the banks of the Tiber River. While the locals were washing clothes, they noticed that if they washed them in certain parts of the river after a heavy rain, their clothes were much cleaner. Thus, the emergence of the first soap—or at least the first use of soap. A soap-like material found in clay cylinders during the excavation of ancient Babylon is evidence that soapmaking was known as early as 2800 B.C. Inscriptions on the cylinders say that fats were boiled with ashes, a soap-making method. Pioneers would boil their wood ash/water solution with fat rendered from butchered animals over an outdoor fire for many, many hours, until a soft soap formed.

While all of those methods truly do produce a pure and natural soap, modern society has manufactured substitutes for the wood-ash solution—sodium hydroxide (also called caustic soda or lye) for solid bars of soap, and potassium hydroxide for liquid soaps. The sodium hydroxide I use in my cold-process soapmaking is made by dissolving salt in cold water just to the point where salt crystals start to fall to the bottom and do not dissolve. Pure salt, with no additives (such as iodine or anti-caking agents) must be used for the process to successfully work. Graphite rods, charged with electricity, are then inserted into the salt solution, and crystals form on the rods. These lye crystals are then spread out, and the liquid is allowed to evaporate, leaving behind the lye crystals we purchase in labeled containers.

So to make the bars of soap I sell here at Farm&Field, using the traditional cold-process method of soapmaking, I must use lye in my process. This can be done completely safely and without incident, as long as proper safety measures are taken into consideration. It is true that fumes from mixing sodium hydroxide with water are harmful and, thus, I take fairly extreme measures and wear a respirator mask. It is also true that the lye-water solution can cause severe burns if it comes in contact with my skin, so I wear full-coverage clothing and gloves. I also wear safety goggles, so as to protect my eyes from any accidental splashes.

But all of these safety precautions are totally worth the beautiful, natural bars of soap that come as the end result. And, in the end, I am able to present to you a completely safe, lovely, skin-nourishing bar of soapy goodness. So wash your worries away, and go enjoy an indulgent, sudsy shower!