Film former

A film former is the ingredient in nail polish or liquid eyeliner that turns from a liquid into a solid, continuous coating as the solvent evaporates, and it decides how hard, glossy and long-wearing the finished coat is.

Also known as: film-forming polymer, film-forming agent, filmvormer, acrylates copolymer

Every product that dries to a coat has a film former. In classic nail polish it is nitrocellulose, dissolved in butyl acetate and ethyl acetate. As the solvents leave, the polymer chains pack together into a hard, glossy film that grips the nail plate. The film dries from the bottom up in a solvent polish and from the top down in a water-based one¹.

Water-based polish uses an acrylic polymer dispersion as its film former. The particles are suspended in water and fuse into a film as the water evaporates, helped by coalescing solvents. It avoids flammable solvents but dries more slowly and has historically worn less well¹.

Secondary film formers and resins improve adhesion and gloss. Tosylamide/formaldehyde resin and ethyl tosylamide did that job in older formulas; both appear on 5-free and 7-free lists, and ethyl tosylamide is restricted in the EU².

Liquid eyeliner works the same way with different chemistry. Pigment is dispersed in water with film-forming polymers such as acrylates copolymer or styrene/acrylates copolymer that dry to a flexible, water-resistant line. A higher film-former load resists transfer better but flakes more and is harder to remove. A plasticiser is added in both cases so the film bends with the nail or the lid.

Written and fact-checked by the India Anaïs editorial team. Every number and rule is linked to its source. How the guides are made.