Hairspray sits inches from a lit curling iron, a hair dryer on high, and sometimes a candle or a cigarette, every single morning in millions of bathrooms. It is worth knowing exactly what is in the can.
Aerosol hairspray is highly flammable. The can contains alcohol (usually ethanol or a similar solvent) as the carrier and propane, butane, or dimethyl ether as the propellant. The spray coming out of the nozzle ignites instantly from a flame, and freshly sprayed hair stays flammable for a minute or two until the alcohol evaporates. Pump hairsprays without propellant are less dangerous but still contain alcohol and still burn while wet.
What's Actually in the Can
- Propellant: propane, butane, isobutane, or dimethyl ether. All flammable gases.
- Solvent: ethanol or denatured alcohol, which carries the polymer and evaporates fast. Flammable liquid.
- Polymers and conditioners: the part that actually holds your hair. Once dry, these are a thin plastic film and not a meaningful fire risk.
Every can carries a "Flammable" warning and an instruction not to use near heat or flame. That is not boilerplate.
The Ways Hairspray Starts Fires
- Spraying near a flame. A candle on the vanity, a gas stove pilot, or a lit cigarette. The mist ignites and the flame runs back toward the can.
- Curling irons and flat irons. Most run between 300 and 450°F, which is above the autoignition point of the propellant and near the flash point behavior of alcohol vapor. Spraying hair and then immediately clamping a 400°F iron on it can produce a brief flash and singed hair. Wait for the spray to dry, or spray after styling.
- Hair dryers. The heating element can ignite hairspray mist that gets pulled into the intake. Spray first, dry second is the wrong order.
- Heat on the can. A can left on a sunny windowsill, in a hot car, or near a space heater can rupture.
Does Hairspray Stay Flammable on Your Hair?
Briefly. The alcohol flashes off within a minute or two, and after that the dried polymer film is no more flammable than your hair already is. The danger window is while it is wet: someone leaning over a birthday cake or a gas burner with freshly sprayed hair has caused real burn injuries. Give it two minutes.
Safe Use
- Spray in a ventilated room away from any flame or heat source.
- Finish heat styling first, then spray, or wait two minutes after spraying before using hot tools.
- Store cans at room temperature, out of sun, never in a car.
- Never puncture or burn an empty can.
Related reading: is aerosol deodorant flammable, is perfume flammable, and is rubbing alcohol flammable.
