There's a direct link between World War II military bug spray and your updo: The misting mechanism in hair sprays was first used in aerosol pesticide technology. Don't worry—your favorite fixer has changed since the 1940s. In the 1970s, scientists discovered that the propellants in hair spray—called chlorofluorocarbons—were rapidly depleting the ozone layer. After years of reformulations, hair sprays are now safer and gentler. There's even the first aerosol that's alcohol-free: Pantene Pro-V Airspray. Here's what else is in your favorite spray.
Polymers: If you find hair sprays too sticky or crunchy, consider this: Early formulas relied on shellac—secreted from bugs—to hold the hair. Now they use a mix of polymers, molecules that form chainlike structures, to lock styles in place. These can be frustratingly stiff, so chemists tinker with them, adding silicones, oils, or keratin protein to create flexibility, says cosmetic chemist Arun Nandagiri, who's been formulating hair sprays since Three's Company was a hit.
Solvent: The polymers are dissolved in a solvent, usually a mix of alcohol and water. Early formulas were more than 80 percent alcohol (as far as solvents go, it kicks ass), but by 1999, California and several other states had put the kibosh on sprays with more than 55 percent alcohol (it can cause health and environmental issues). Pantene was able to eliminate alcohol entirely by mixing polymers with a light, water-based solvent. As the water evaporates, the polymers remain to set hair without feeling sticky or wet.
Propellant: To get the polymers and solvents out of the can, you need a propellant. Chlorofluorocarbons got the job done—but at the expense of the ozone layer. Hydrocarbon propellants aren't as bad for the environment but can make hair feel unappealingly sticky. Most hair sprays now turn to dimethyl ether, a colorless gas propellant that is highly flammable but otherwise safe.
How to get perfect beachy hair: