A: The culprits are resins. Nearly all hairsprays contain them, says Brenda DuVal, executive vice president of research and development at Paul Mitchell. Resins are what give the product its holding power, but they also tend to dry up between uses and clog the nozzle. To unclog it, remove the nozzle, run it under hot water—which will soften the resins—and wipe it clean. Don't ever poke at the nozzle with a pin or a toothpick, since this can damage the spray system, says Chris Boone, lead chemist in research and development for TRESemmé.
Bottom line: If rinsing the nozzle under hot water doesn't help, remove it and soak it in rubbing alcohol for a couple of hours. The alcohol should dissolve the clogging resins