Lye: Soap’s Dirty Little Secret

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

I could go on and on, but I digress. If you don't believe me, go ahead and read those ingredients on store-bought soaps. Anytime you see the word "Sodium" as part of the ingredient list it means lye was used. Just so you know, we at Victorialily Soaps use "Sodium Hydroxide" on our own labels.

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 wonderful cleansing experience.

Soapmaker Safety Tips:

Working with lye (sodium hydroxide) requires careful handling to ensure safety.

1. Wear Protective Gear

• Gloves: Use chemical-resistant gloves (e.g., nitrile) to protect your skin.

• Goggles: Protect your eyes from lye splashes.

• Long Sleeves & Apron: Cover your skin to prevent burns.

• Mask: Helps reduce inhalation of fumes when mixing lye.

2. Work in a Well-Ventilated Area

Lye releases fumes when mixed with liquid. Work near an open window, under an exhaust fan, or outdoors if possible.

3. Mix Lye into Liquid, NOT the Other Way Around

Always add lye to water (or milk), never water to lye—this prevents violent reactions and splashing.

4. Use Heat-Resistant Containers

--Lye solutions heat up rapidly. Use:

--Stainless steel or heavy-duty plastic (#5 PP or #2 HDPE)

--Avoid aluminum, tin, or glass (can corrode or shatter)

5. Stir Gently to Prevent Splashes

Use a heat-resistant spoon or silicone spatula when mixing.

6. Keep Vinegar Away from Spills

While vinegar neutralizes lye, it can create heat when poured directly onto concentrated lye. Instead, use running water to rinse affected skin.

7. Store Lye Safely

Keep lye in a sealed, labeled container away from children, pets, and moisture.

8. Clean Up Immediately

Rinse lye-contaminated tools with plenty of water and white vinegar.

Wipe up spills with a damp vinegar cloth and dispose of properly.

9. Have a Safety Plan

►Skin Contact: Rinse immediately with running water for at least 15 minutes.

►Eye Contact: Flush with cool water and seek medical attention.

►Ingestion: Call poison control immediately.

10. Be Prepared & Stay Focused

♥ Work in a calm, distraction-free environment.

♥ Organize all ingredients and tools before starting.

Truth: You cannot make soap without lye.