what exactly is lye soap?

You might have heard of “lye soap” and imagined something harsh or old-fashioned, the kind of soap your grandma would have made. But the truth is, lye soap is simply real soap—and it’s been around for centuries.

What is Lye?

Lye is a strong alkali (sodium hydroxide for bar soap, potassium hydroxide for liquid soap) that’s essential for making soap. When lye is mixed with fats or oils, a chemical reaction called saponification takes place. This reaction transforms the oils into soap and creates glycerin, a natural moisturizer.

Is There Lye in the Soap I Use?

Actually, no lye remains in the finished product. During saponification, all the lye reacts with the oils, leaving only soap and glycerin.

The “Old-Fashioned” Connection

Traditional lye soap was often made with animal fats like lard or tallow. Nowadays, we often use rich plant-based oils such as olive, coconut, and shea butter for a variety of qualities and skin benefits. We also still like to use a bit of tallow sometimes.

Why Make Lye Soap?

• It’s the only way to make true soap—without lye, you’d just have oily water or detergent.
• It’s gentle when formulated well, despite its tough-sounding name.
• It retains natural glycerin, which helps keep skin soft.

So, the next time you hear “lye soap,” you'll know it’s just authentic, real soap—crafted the way it’s been done for generations, but with today’s skin-friendly touches.