Nitrocellulose, the polymer that makes nail polish a film

Turn a bottle of polish over and nitrocellulose is usually the second or third name on the list, after the solvents. It is the ingredient that becomes the manicure. Everything else either helps it onto the nail, keeps it flexible, makes it stick or colours it.

The polymer is older than the cosmetic. It began as an explosive in the 1840s, became photographic film and billiard balls, went into car lacquers and reached nails in the early twentieth century. A modern polish still relies on the same property that made all of those possible: a solution that leaves a tough transparent film when its solvent evaporates.

What is nitrocellulose?

Nitrocellulose is cellulose nitrate, a polymer made by treating cellulose with a mixture of nitric and sulphuric acid so that nitrate groups replace some of the hydroxyl groups along the chain. Cellulose itself will not dissolve in nail polish solvents. Once nitrated, it dissolves readily in organic solvents such as acetone and esters, and on evaporation it leaves a colourless, transparent, flexible film (Wikipedia).

The degree of nitration decides the grade. Most lacquers are prepared from the dinitrate, whereas explosives are mainly the trinitrate, and material with more than 13% nitrogen is the insoluble guncotton used for blasting (Wikipedia). Nail polish uses the lower-nitrogen, soluble grades, which are sold to formulators damped with isopropyl alcohol or a similar liquid because the dry polymer is flammable.

On the INCI list the name is Nitrocellulose. The European Commission's ingredient database records its function as film forming, which is the whole of its job in polish.

Where did nitrocellulose nail polish come from?

Henri Braconnot first made a nitrated wood fibre in 1832, and Christian Friedrich Schönbein worked out the practical method around 1846, when a spilled mixture of nitric and sulphuric acid soaked into a cotton apron that later caught fire (Wikipedia). In 1868 John Wesley Hyatt plasticised nitrocellulose with camphor to make celluloid, the first commercial plastic, and camphor stayed in nail polish as a plasticiser for a century afterwards.

Nitrocellulose lacquers reached nails from the varnish and lacquer trade. The Bijou Chemical Company of New York was producing a nitrocellulose-based polish as early as 1903, and amyl acetate, patented as a lacquer solvent in 1882, gave the early polishes a more durable, transparent film than the alcohol and ether mixtures before it (Cosmetics and Skin).

The DuPont Duco car lacquers of the early 1920s are often named as the origin of the modern formula (C&EN). The link is looser than the story suggests: Duco took at least twelve hours to dry and needed polishing for gloss, while nail lacquer dried in minutes, so the two evolved side by side from the same lacquer chemistry (Cosmetics and Skin). Pigments replaced soluble dyes by the late 1920s, and the polish we recognise today, opaque, glossy and quick to dry, was in place by the 1930s.

Why does nitrocellulose give gloss and hardness?

Nitrocellulose dries to a film with hardness, toughness and resistance to abrasion (Cosmetics and Skin). The long chains pack into a dense, smooth surface as the solvent leaves, and a smooth dense surface reflects light in one direction, which the eye reads as gloss. The same density is what resists keys, typing and the edge of a coin.

The polymer is brittle on its own, so every polish adds a plasticiser to let the film bend with the nail, and a resin to improve adhesion and add depth to the gloss (Compound Interest). The balance between the three sets the character of a polish. More nitrocellulose gives a harder, glassier, more chip-prone film; more plasticiser gives a softer film that dents; more resin gives grip and a warmer gloss.

Nitrocellulose also yellows slowly in ultraviolet light, which is why most clear top coats and pale shades contain a UV absorber such as benzophenone-1 (C&EN). A bottle kept in a sunny bathroom will drift warmer than one kept in a drawer.

How does nitrocellulose compare with the alternatives?

The only established alternative in air-dry polish is an acrylic polymer dispersion in water, the system used in water-based polish. It has no flammable solvent and almost no smell, and the film forms as water and small amounts of coalescent evaporate and the polymer particles fuse. It dries more slowly than solvent polish, can absorb some water into the nail as it dries, and historically wore less well and removed with more difficulty (Personal Care Magazine).

Drying and removal figures come from Dutch salon guidance and from the Personal Care Magazine review of water-based systems (Nagelstudios.nl; Personal Care Magazine). Some so-called breathable polishes keep nitrocellulose and add polymers borrowed from contact-lens chemistry to make the film more permeable to water vapour, which changes permeability but not the drying mechanism.

Is nitrocellulose safe in nail polish?

Nitrocellulose is a large polymer that stays on the surface of the nail as a solid film. It does not dissolve in water or skin oils, and it is not restricted under Annex II or Annex III of Regulation (EC) No 1223/2009; a polish sold in the EU is assessed as a finished formula under Article 10 of that regulation (EUR-Lex). The safety questions around nail polish concern the solvents during application and a few historical plasticisers, not the film former.

The practical hazard is fire. Nitrocellulose has a very low flash point and the solvents it is dissolved in are flammable too, so polish is stored away from heat, applied away from candles and kept with the cap tight (Wikipedia). A dried film on the nail is a tiny amount of material and is not a fire risk.

How to get the best from a nitrocellulose polish

You will need: nail polish remover or rubbing alcohol, a base coat, the colour, a glossy top coat and a bottle of polish thinner for older bottles.

1. Degrease the nail with remover or alcohol so the resin can grip bare keratin.
2. Paint thin coats. Nitrocellulose sets from the nail outward, and a thin coat hardens through; a thick one skins over and stays soft beneath.
3. Wait 1 to 2 minutes between coats so each can release its solvent (Manucurist).
4. Finish with a glossy top coat, which adds a harder film over the colour and contains the UV absorber that slows yellowing.
5. Keep the cap tight and the bottle out of sunlight. If the polish thickens, add a few drops of thinner, which replaces lost solvent, and never remover, which is not part of the formula.

A crème such as Violet Spell from India Anaïs is a nitrocellulose lacquer of this classic type, with no monomer and no photoinitiator. The first edition is sold out, and the next edition is planned for spring 2027.