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Truth: You cannot make soap without lye.
Sorry folks, but that's the way it is. Lye is soaps dirty little secret. In his book "Scientific Soapmaking", Kevin M. Dunn writes: "...the true art of soap making is...to create a bar of soap that is tantalizing and pleasing to the senses - and to do it within the constraints of science and chemistry...";
...and lye is an indispensable part of that chemistry.
Even though the word "lye" makes people gasp in horror - and no one wants to hear it's in a skin product! - it plays a crucial role in the soapmaking process: transforming raw ingredients into the luxurious bars we use for cleansing. This scream-worthy substance might make you never want to use soap again, but it's an essential component that contributes to the alchemy of soap.
In soapmaking, lye acts as a catalyst in a chemical reaction called saponification. This reaction involves the combination of fats or oils with lye to produce soap and glycerin. The result is a product that effectively cleanses while maintaining skin hydration.
The first step in soapmaking is selecting the oils or fats. Different oils bring distinct qualities to the soap, influencing its texture, lather, and moisturizing properties. Lye then comes into play as it reacts with these oils through a carefully measured process. This reaction is critical because it determines the characteristics of the final soap.
Once the saponification reaction is complete (gel phase), the soap mixture needs to cure for about 4-6 weeks...yes, WEEKS not days. This allows any remaining traces of lye to react fully and ensures a milder, gentle final product. During this curing process, the soap hardens and becomes less alkaline, making it safe to use on the skin.
Soap makers often experiment with different oils and additives to create unique blends that cater to specific skin types and preferences. Lye (also known as Sodium Hydroxide) provides the flexibility for us to customize our soap recipes, each with their own distinct properties.
But wait! How come you never see the term lye on soap labels?? Manufacturing companies and commercial marketers (including handmade soapmakers) have come up with some creative ways to add lye to their ingredient lists without actually including the taboo word. Here's a list of some of those substitutes:
Sodium Hydroxide
Saponified Oils
Caustic Soda
NaOH
Sodium Hydroxide Solution
Alkali Salt
Saponification Agent
Soapmaker's Catalyst
Sodium Tallowate
Potassium Tallowate
Pot Ash
Soda Lye
Caustic Potash
White Caustic
Sodium Caustic
Sodium Hydrate
Hydroxide of Sodium
Alkaline Hydroxide
Caustic Alkali
Saponified Oils
In the end, no matter what you call it, it's still lye. Without it, the oils and fats would remain a gooey mess. Lye helps transform that gooey mess into high-quality solid soap that conditions your skin instead of stripping it - which actually sounds like magic to me. So, the next time you lather up with a beautifully crafted bar, appreciate the role lye plays in transforming a blend of oils and butters into a luxurious cleansing experience.