Lye on the Label: Sodium Hydroxide INCI for Soap Makers

Every soap maker hits this question eventually, usually right when they're filling out an ingredient list for the first time: you poured lye into your oils, but lye isn't in the finished bar anymore, chemically speaking. So what actually goes on the label and in the filing?

What saponification actually does to sodium hydroxide

Sodium hydroxide, the chemical you know as lye, reacts completely with the fatty acids in your oils during saponification. If your recipe is properly formulated with the right amount of superfat, there's no free sodium hydroxide left in a cured bar. What's left is a mix of sodium salts of fatty acids, which is the actual chemical definition of soap, plus glycerin as a byproduct, plus whatever excess unreacted oil you built in as superfat.

This matters for labeling because you generally aren't declaring "Sodium Hydroxide" as an ingredient in a properly cured bar, since it isn't present in the finished product anymore. What you declare instead are the resulting saponified products.

How the INCI naming actually works

This is where it gets specific, and where a lot of new soap makers get tripped up because the INCI names look nothing like the oils they started with. The INCI system names saponified oils by combining "Sodium" with the fatty acid source. Some common examples:

Oil used	Resulting INCI name
Olive oil	Sodium Olivate
Coconut oil	Sodium Cocoate
Palm oil	Sodium Palmate
Castor oil	Sodium Castorate
Shea butter	Sodium Shea Butterate
Sunflower oil	Sodium Sunflowerate

If you made a bar with olive oil, coconut oil, and castor oil, your ingredient declaration lists Sodium Olivate, Sodium Cocoate, and Sodium Castorate, in that general order of concentration, not "Olive Oil, Coconut Oil, Castor Oil" and definitely not "Sodium Hydroxide."

When sodium hydroxide does appear

There's a real exception here worth knowing. If your bar has any unreacted lye, from an error in your lye calculation, insufficient cure time, or an intentionally low superfat formula that leaves excess alkalinity, then Sodium Hydroxide can legitimately need to appear on the ingredient declaration, because it's genuinely present in the finished product. This is one of several reasons proper cure time and an accurate lye calculator matter beyond just bar quality: an under-cured or poorly calculated bar isn't just a worse bar, it may have a different actual ingredient composition than what you intended to sell.

If you sell a cold process soap that hasn't fully saponified, or that tested with a high pH indicating leftover alkalinity, that changes what belongs on your filing. This is a case where the honest answer depends on your actual finished product, not your recipe on paper.

What about the superfat oils?

Superfat, the deliberate excess of oil left unreacted to keep the bar gentle and moisturizing, does stay in its original oil form since it never reacted with the lye. So a bar with 5% superfatted olive oil would show both Sodium Olivate (from the saponified portion) and potentially plain Olea Europaea (Olive) Oil, listed by its full INCI botanical name, for the superfat portion, depending on how your formula and finished product actually break down.

Glycerin, and why it isn't an "added" ingredient

Glycerin is a natural byproduct of saponification, not something soap makers add separately in cold process soap. It still gets its own line on the ingredient declaration, using its INCI name Glycerin, because it's genuinely present in the finished bar even though nobody poured it in from a bottle.

Filing this correctly

For Health Canada's Cosmetic Notification Form, you're declaring ingredients by INCI name with concentration or a concentration range, which for a saponified bar means working out the approximate final percentages of each sodium salt, superfat oil, and glycerin in the cured bar, not the percentages of raw oils and lye you started with in your recipe. This is a genuinely different calculation than most other cosmetic categories, since the chemistry transforms your inputs rather than just diluting them.

If working out saponified INCI names and their resulting concentrations feels like the trickiest part of filing a soap line, that's a common sticking point, and it's exactly the kind of ingredient mapping Cosmetic Comply is built to handle before it screens your list against the Hotlist and moves it toward a CNF filing.