If you've ever read the ingredient list on a bar of Le Joyau d'Olive soap and paused at "sodium hydroxide" — this post is for you.
The Question We Get Asked Most Often
"Wait — your soap contains caustic soda? Isn't that dangerous?"
It's a fair question. Sodium hydroxide — commonly known as caustic soda or lye — sounds alarming. It's the same compound used to unclog drains. It can burn skin on contact. In its raw form, it demands respect and careful handling.
And yet, it is one of four ingredients in Le Joyau d'Olive. So what is it doing there — and should you be concerned?
The short answer is no. And the reason why is one of the most beautiful examples of chemistry in everyday life.
What Caustic Soda Actually Is
Sodium hydroxide (NaOH) is a naturally occurring mineral compound. It has been used in soap making for thousands of years — long before it had a chemical name. Ancient civilisations discovered that wood ash (which contains potassium hydroxide, a close relative) mixed with animal fat produced a substance that cleaned. They didn't know why. They just knew it worked.
The why is saponification — and understanding it changes everything about how you think about caustic soda in soap.
The Transformation: What Happens During Saponification
When sodium hydroxide meets virgin olive oil, a chemical reaction begins. The NaOH reacts with the fatty acids in the oil — completely, irreversibly, and beautifully. This reaction is called saponification, from the Latin sapo, meaning soap.
What emerges from this reaction is not caustic soda and not olive oil. It is something entirely new: soap — the sodium salt of fatty acids — and glycerol, a natural humectant that draws moisture to the skin.
This is the crucial point: by the time saponification is complete, there is no sodium hydroxide left in the bar. None. It has been entirely consumed in the reaction — transformed into the very thing that makes the soap gentle, nourishing, and safe.
The caustic soda does not survive into the finished product. It is the catalyst that initiates the transformation, and then it is gone.
Why We List It on the Label
If caustic soda is no longer present in the finished soap, why does it appear on the ingredient list?
Because transparency demands it. We list every ingredient used in the making of our soap — including the ones that are no longer present in their original form. This is not only honest; it is the correct way to disclose a soap's origins. Some brands list only the final saponified ingredients (sodium olivate, for olive oil). We prefer to show you the full picture: what went in, and why.
We believe you deserve to know exactly how your soap was made — not just what it contains at the end.
The Difference Between Soap and Detergent
Here is something worth knowing: most commercial "soaps" are not soap at all. They are synthetic detergents — made with surfactants derived from petroleum, combined with artificial fragrance, preservatives, and binding agents. They may look like soap, smell like soap, and lather like soap. But they have never undergone saponification. No caustic soda was used in making them, because no real soap-making took place.
The irony is striking: the products that consumers worry about — natural soaps listing sodium hydroxide — are the cleanest, most honest products on the shelf. The ones that don't list it are often the ones worth questioning.
Why Cold Saponification Makes the Difference
Not all soap-making processes are equal. Industrial soap is made at high temperatures, which speeds up the reaction but destroys much of the natural goodness in the oils — the omega fatty acids, the vitamins, the antioxidants.
At Le Joyau d'Olive, we use the cold saponification method. The reaction takes place at ambient temperature, preserving everything that makes virgin olive oil extraordinary for the skin: Omega 3, 6, and 9 fatty acids; vitamins A and E; antioxidants; and the natural glycerol produced during saponification itself.
This is why our soaps nourish rather than strip. Why they leave the skin feeling hydrated rather than tight. Why dermatologists recommend olive oil soap for sensitive skin, eczema, and psoriasis.
The cold process is slower. It requires more care, more expertise, and more patience. The bars must then cure for five full months in our stone-vaulted cellars — a step most modern manufacturers skip entirely. This curing period allows the saponification to complete fully, the water to evaporate gradually, and the soap to reach its ideal hardness, gentleness, and longevity.
Our Four Ingredients — And Nothing Else
Le Joyau d'Olive bar soaps are made from four ingredients:
- Virgin olive oil — cold-pressed, sourced from Lebanese groves, rich in omegas and vitamins
- Water — pure, used to dissolve the sodium hydroxide and initiate the reaction
- Sodium hydroxide (caustic soda) — the catalyst that transforms oil into soap; absent in the finished bar
- One pure essential oil — single-origin, undiluted, chosen for its skin benefits and scent
That is the complete list. No synthetic fragrance. No preservatives. No palm oil, no coconut oil, no fillers, no additives. No ingredient you cannot pronounce, explain, or find in nature.
We did not arrive at this formula by removing things. We built it this way from the beginning — because we believe that everything a bar of soap needs is already present in virgin olive oil, and everything else is noise.
The Bottom Line
Caustic soda in soap is not something to fear. It is something to understand — and once you do, it becomes one of the clearest signals that you are holding a real soap, made the honest way.
If you see sodium hydroxide on a soap label, it means saponification happened. It means someone made actual soap, the way soap has been made for thousands of years. It means there is nothing hiding behind a long list of synthetic alternatives.
At Le Joyau d'Olive, we are proud to list it. It is part of our story — the story of a process unchanged since 1804, carried out by hand, one batch at a time, in a stone workshop in South Lebanon.
The caustic soda is gone by the time the soap reaches you. What remains is pure, honest, extraordinary soap.
Nothing more. Nothing less. Nothing to be afraid of.
Want to learn more about what goes into Le Joyau d'Olive?
Read our post on Total Fatty Matter — what it tells you about a soap's quality, or explore our FAQ for answers to the most common questions about natural soap making.