Contents
Pigmented lacquer that dries by solvent evaporation. Nail polish is essentially automotive-style nitrocellulose lacquer adapted for keratin, and its modern history is best told through the ingredients it has removed rather than the ones it contains.
What is in it
| Class | Doing what | Names |
|---|---|---|
| Film former | The hard shell | Nitrocellulose |
| Resin | Adhesion and gloss | Tosylamide/formaldehyde resin, or replacements |
| Plasticiser | Flexibility so it does not shatter | Camphor, acetyl tributyl citrate, trimethyl pentanyl diisobutyrate |
| Solvent | Keeps it liquid; evaporates | Ethyl acetate, butyl acetate, isopropyl alcohol |
| Pigment | Colour | Iron oxides, titanium dioxide, certified lakes, mica, ultramarines |
| Suspending agent | Stops pigment settling | Stearalkonium hectorite |
| UV stabiliser | Stops the colour changing in light | Benzophenone-1 |
Nothing is absorbed and nothing reacts with the nail. Polish sits on the nail plate, which is dead keratin, and comes off with solvent.
The "free-from" numbers
The counting convention — 3-free, 5-free, 7-free, and upward — began with three ingredients of genuine concern and has since become a marketing ladder with no standard definition. What the original three were:
- Dibutyl phthalate (DBP) — a plasticiser, a reproductive toxicant, and restricted in the EU as a CMR substance under Article 15 of the Cosmetics Regulation.
- Toluene — a solvent, neurotoxic on inhalation, an occupational concern in salons.
- Formaldehyde / tosylamide-formaldehyde resin — a carcinogen and a significant contact allergen. Note the distinction: the resin is a polymer and is not free formaldehyde, but it is a well-documented allergen in its own right.
Beyond those three, the additional "free-from" claims cover camphor, xylene, ethyl tosylamide, parabens, animal-derived ingredients and others, and there is no rule about which ingredients any given number refers to. Treat the numbers as a signal of intent rather than a specification.
Salon air, and where the risk actually is
For a consumer painting their nails occasionally, solvent exposure is trivial. For a nail technician working eight hours a day in a small room, cumulative exposure to solvent vapour, acrylic monomer and dust is a genuine occupational health issue, and ventilation and source capture are the controls that matter. This is a workplace safety question, not a cosmetic safety one, and it sits with OSHA rather than FDA.
Where it sits in the rules
Cosmetic in the US — FDA primary category (10) manicuring preparations. The binding constraint is colour additives: each must be approved by FDA for the intended use, and certified colours must come from FDA-certified batches.
Two prohibited-list entries touch this category. Methylene chloride is one of the eleven substances FDA specifically prohibits, and it was formerly used as a solvent. Chloroform is another.
In the EU, permitted colorants come from the Annex IV closed positive list of 153 entries, and CMR substances of categories 1A, 1B and 2 are banned under Article 15 — which is what removed DBP.
Shelf life
Two years unopened, 12–24 months after opening. The failure mode is solvent evaporation: polish thickens, then goes stringy, then gloopy.
Do not thin it with acetone or polish remover — that dissolves the film former and produces a polish that chips immediately. Use a proper nail polish thinner, which is the correct solvent blend, and only a drop or two. Keep the bottle neck clean so the cap seals, and store upright, cool and out of sunlight.
Related
- Nails — the shelf this sits on, and the rest of it.
- Cosmetics — what the label is legally allowed to say, and the full catalogue.
- The rest of Colour — Gel Polish · Dip Powder · Base Coat · Top Coat · Quick-Dry Drops.
- Nail Polish Remover — the other half of the cycle.
- Regulatory statements here follow the FDA and EU sources listed on Cosmetics, read 16 August 2026.