Is There Lye in My Soap?
Many people ask: Is there lye in natural soap?
If you’re asking if we use lye (sodium hydroxide) to make Chagrin Valley natural soap, the answer is — yes, of course.
No lye — no soap.
All cold process soap is made with lye (sodium hydroxide mixed with a liquid). Any skin or hair cleansing product made without sodium hydroxide is not soap — it is a detergent.
But if your question is:
Is there lye in a finished bar of Chagrin Valley natural soap or shampoo?
The answer is no.
Once the soapmaking process — called saponification — is complete, the lye and oil molecules have combined and chemically transformed into soap and glycerin. When formulated correctly, all of the sodium hydroxide is consumed in this reaction. No free lye remains in the finished bar.
Why Doesn’t It Say “Lye” on My Soap Ingredient Label?
If a product is real soap, it must be made with lye — even if the words “sodium hydroxide” or "lye" do not appear on the label.
Handmade soaps and some commercial bars often list ingredients such as:
- Saponified oils (oils reacted with sodium hydroxide)
- Sodium cocoate (coconut oil + sodium hydroxide)
- Sodium palmate (palm oil + sodium hydroxide)
- Sodium palm kernelate (palm kernel oil + sodium hydroxide)
- Sodium tallowate (tallow + sodium hydroxide)
- Sodium olivate (olive oil + sodium hydroxide)
We once had a customer return a bar of our Castile & Shea Soap because her dermatologist advised her to avoid soap made with lye — and recommended Dove instead.
While the words "sodium hydroxide" or “lye” do not appear on Dove’s ingredient label, the first ingredients listed were sodium tallowate, sodium cocoate, and sodium palm kernelate.
These are simply the chemical names for oils after they have reacted with sodium hydroxide. When oils combine with lye during saponification, they are converted into these “sodium” salts — which are the actual soap.
Some soapmakers avoid listing “sodium hydroxide” because of widespread misunderstanding and concern among consumers. Instead, they may list “saponified oils,” which describes the same chemical process in simpler language.
What Is Sodium Hydroxide?
Sodium hydroxide — commonly called lye — is essential to the soapmaking process. It is the alkali (base) that reacts with oils and butters during saponification.
Real cold-process soap cannot be made without it.
Historically, lye was made by filtering rainwater through hardwood ashes. Because there was no way to measure strength precisely, early lye solutions were often too strong. That is why old-fashioned “lye soap” gained a reputation for being harsh.
Today, sodium hydroxide is produced in controlled laboratory conditions, allowing for exact formulation.
If you enjoy chemistry, here is a simplified explanation of how it is made:
- Sodium hydroxide (NaOH) consists of sodium (Na⁺) and hydroxide (OH⁻) ions.
- It can be produced from salt water through a process called electrolysis.
- When an electric current passes through salt water (NaCl + H₂O), the compounds separate into sodium ions, chlorine gas, hydrogen gas, and hydroxide ions.
- The sodium and hydroxide ions then combine to form NaOH.
In other words, sodium hydroxide begins with something very simple — salt water.
People have asked, how can soap be natural or organic if it is made with lye? Cold-process soap is considered natural because the lye (NaOH) is entirely consumed during the saponification process, reacting with oils to create soap and glycerin. No lye remains in the finished bar.
A similar example in food is the use of baking soda (sodium bicarbonate) in natural or certified organic bread and baked goods. This ingredient is essential to the chemical reaction that allows dough to rise, but it is not present in its original form once baking is complete.
Although neither sodium hydroxide (NaOH) nor baking soda is organic, they are among the allowable ingredients included in USDA organic standards since they have applications in farming as well as food production.
Saponification: The Chemical Reaction of Soapmaking
(The science teacher in me could not resist.)
If you remember high school chemistry, you may recall that when an acid and a base react, they neutralize each other and form a salt.
In simple terms, saponification is the name for a chemical reaction between an acid and a base to form a salt called "soap."
Sodium hydroxide is the alkali (base), and the acids are the fatty acids that make up the triglycerides present in oils and butters.
For each unique soap recipe, a precise amount of fat (oils and butters) is needed to ensure that all of the lye has been transformed into soap. There is no set relationship between the number of molecules of water needed per molecule of oil. Water is simply used to dissolve the NaOH molecules so they can react with the oils.
Once we select the oils and mix them with sodium hydroxide and a liquid, the molecules combine, the saponification reaction begins, and a new substance is created: soap.
The Saponification Reaction
Notice there is no sodium hydroxide on the product side of the equation. The reaction is complete.
A Simple Chemistry Analogy
In every chemical reaction, the atoms of starting substances (reactants) are rearranged to create new substances (products) with different chemical properties. The original substances no longer exist in their initial form. Here is another example:
The element sodium is a highly reactive metal that explodes on contact with water.
Chlorine is a toxic gas that has actually been used as a chemical weapon.
But when they react together, they form sodium chloride — ordinary table salt.
The explosive sodium and poisonous chlorine gas are completely transformed into a safe, edible compound.
The saponification reaction works the same way. When soapmaking is done correctly, all the sodium hydroxide (NaOH) is consumed and becomes part of the soap molecule.
Superfatting: Why Formulation Matters
Not all handmade soap is created equal.
For every soap recipe, there is a precise amount of oil required to ensure that all of the lye is fully consumed during saponification.
Understanding that chemistry is essential. Soapmaking is rooted in science — in exact measurements, molecular reactions, and predictable outcomes.
Creativity and craftsmanship matter, but they must rest on a solid foundation of chemistry.
Once you understand how the reaction works, you can begin to control the qualities of the finished bar.
Superfatting is one example. We intentionally add more oils or butters than the lye can convert into soap. These extra oils remain in the finished bar and are released onto the skin during washing.
While many soapmakers use a standard 5% superfat, we prefer a higher percentage. This creates a bar that feels clean but never dry — balanced and nourishing without being greasy or overly soft.
Interesting Notes About Lye
Sodium hydroxide has many uses beyond soapmaking.
In food preparation, lye baths give pretzels their distinctive flavor and glossy crust. It is used to process hominy and to cure olives and pickles. It is also used to remove skins from fruits and vegetables before canning.
Sodium hydroxide is also used in pharmaceutical manufacturing, including the production of aspirin and certain anticoagulants. Municipal water systems may use it to adjust pH and help remove heavy metals.
The Final Word on Lye
It’s natural to have questions about lye. The important thing to understand is that although lye is essential to making real soap — it does not remain in the finished bar.
Through saponification, sodium hydroxide is completely transformed into soap and glycerin. When the soap is properly made, the reaction is complete — leaving behind soap, glycerin, and a bar designed to cleanse gently and feel good on the skin.
Real soap begins with lye — and ends with none.
Continue Exploring Natural Soap
Curious to learn more? See the articles below.
- A Deep Dive Into The Chemistry of Natural Soap Making
- Why Use Natural Soap? What Makes It Different?
- How Does Natural Soap Create Lather?
- How We Make Natural Soap Bars
- Are All Handmade Soaps the Same?
This blog was updated in 2025 for organization, flow, and clarity
