Solvent INCI Names: Water, Alcohol, and the Glycols

Solvents feel like the boring line at the top of an ingredient list, right up until you realize half of them have INCI names that do not match what anyone actually calls them. Water becomes Aqua. Rubbing alcohol becomes something entirely different from the alcohol in your tincture. Get one of these wrong on a filing and you have mislabeled the single most common ingredient in the formula.

Water is Aqua, full stop

This is the one everyone eventually memorizes, but it is worth stating plainly because new formulators sometimes list "Water" or "Deionized Water" out of habit. The INCI name is Aqua. Some formulations list it as "Aqua/Water/Eau" to cover multiple markets on one label, which is fine, but the actual INCI designation your filing should reference is Aqua.

Alcohol is not one ingredient

This is where most of the actual confusion lives. "Alcohol" on an ingredient list can mean at least three different things depending on what your supplier shipped:

• Alcohol (INCI) refers to ethanol that has not been denatured, sometimes used in products where non-denatured ethanol is specifically required or permitted.
• Alcohol Denat. refers to ethanol that has been deliberately made undrinkable through the addition of a denaturing agent, which is the form used in the overwhelming majority of cosmetic and personal care formulas, including toners, perfumes, and hand sanitizers.
• SD Alcohol followed by a number (like SD Alcohol 40) is a US-specific designation tied to a particular denaturant formula recognized by US tax authorities, and it functions the same way as Alcohol Denat. but the labeling convention differs by market.

If your supplier's certificate of analysis says "ethanol, denatured with [some specific denaturant]," your INCI is Alcohol Denat., not plain Alcohol. Filing the wrong one is a small-looking error that is still an inaccurate declaration.

The glycols and glycol-adjacent solvents

Propanediol, Butylene Glycol, Propylene Glycol, and Dipropylene Glycol are all distinct INCI entries even though marketing copy sometimes uses "glycol" loosely as a catch-all. Each has its own CAS number and its own typical function, ranging from humectant to solvent to viscosity modifier, and none of them are interchangeable on a filing just because they behave similarly in a formula.

Reference table

Common term	INCI name	Typical CAS number	Typical function
Water	Aqua	7732-18-5	Solvent, base
Non-denatured ethanol	Alcohol	64-17-5	Solvent, astringent
Denatured ethanol	Alcohol Denat.	Varies by denaturant used	Solvent, astringent, carrier
US-specific denatured ethanol	SD Alcohol 40 (or similar number)	Varies	Solvent, carrier
1,3-propanediol	Propanediol	504-63-2	Humectant, solvent
Butylene glycol	Butylene Glycol	107-88-0	Humectant, solvent, texture
Propylene glycol	Propylene Glycol	57-55-6	Humectant, solvent
Dipropylene glycol	Dipropylene Glycol	25265-71-8	Solvent, fragrance carrier

Treat the CAS numbers here as a starting reference, not gospel. Some of these solvents, particularly Alcohol Denat., do not have one fixed CAS number because the denaturant blend varies. Always confirm the specific number against your supplier's documentation rather than assuming a table like this one covers your exact lot.

Why this matters more than it looks

A CNF or any market's ingredient filing is only as accurate as the INCI names behind it. Solvents are usually the first or second ingredient by weight in liquid formulas, so an error here is not a rounding issue buried at the bottom of the list, it is a mistake in the most visible line of your formula. Regulators and reviewers checking a filing tend to notice solvent errors quickly because they are so common and so easy to catch.

If you are mapping a full ingredient deck from supplier documentation and want the solvent lines, the glycols, and everything else matched correctly to INCI and CAS before a filing goes out, that is precisely the groundwork Cosmetic Comply does automatically, catching the Alcohol versus Alcohol Denat. kind of mismatch before it becomes a filed inaccuracy rather than after.