How hairspray is made

A spritz of hairspray leaves a thin plastic film on the hair once the solvent in each droplet has evaporated.

stations: 7
things upstream: 54
raw sources: 21
steps from the ground: 7

The short version

Most of a can of hairspray is solvent such as ethanol, carrying only a small volume of film-forming polymer. The liquid is blended and filled into open cans. On the line, a cap holding valve and dip tube sits loosely on top, a sealed bell pushes propellant in under it, and the same head then crimps the cap down for good.

Blend the polymers

Copolymers of polyvinylpyrrolidone and polyvinyl acetate are mixed with plasticizers, surfactants and luster agents. Adjusting the polymer mix sets whether the hold is flexible, medium or maximum.

Goes in
Polyvinylpyrrolidone Plasticizer
Dissolve in solvent

Solvents such as ethanol and isopropanol fill most of the can, while the polymer concentrate is only a small part of the volume. Fragrance goes in here too.

Goes in
Ethanol Perfume
Fill the open cans

Cans of lacquered tinplate or aluminum travel to a filling unit, where liquid product drops through their open tops.

Goes in
Tinplate
Seat the cap loosely

At the next unit, a closure cap fitted with a valve and dip tube is placed on each can mouth without being fixed down, so gas can still get underneath.
Charge under the cap

A bell chamber seals over the top of the can, and propellant entering it lifts the cap and flows in. Hydrocarbons such as propane, butane and isobutane are common, and dimethyl ether is often added since it also works as a solvent.

Goes in
Propane
Crimp the valve cap

The same head pushes the cap onto the mouth and crimps it permanently into a hermetic seal. This is the undercap method, one way aerosol lines load propellant.
Fit the button and pack

An actuator button goes on over the valve, with a nozzle that controls droplet size. Finished cans then leave for packing.

End of the lineHairspray

Worth repeating

Norwegian engineer Erik Rotheim won the first spray can patent in Oslo in 1927.
The modern spray can was put to use in 1941 by two U.S. entomology researchers, as the aerosol bomb for insects.
Chlorofluorocarbons were replaced after Rowland and Molina proposed in 1974 that they were depleting the ozone layer.