To unclog an aerosol can, remove the nozzle and clean it separately from the rest of the can. Soak the nozzle overnight in a solvent appropriate to the material clogging the can and carefully remove any debris, taking care not to damage the tube.
Solvents that can clean aerosol nozzles include water, rubbing alcohol, mineral oil and methylated spirits. Gentler solvents remove clogs in household products, such as hairspray, while stronger solvents, such as mineral oil, are necessary for cleaning more difficult clogs. Spray paint is one common aerosol product that requires stronger solvents to clean.
Nozzles are the only part of an aerosol can that can be cleaned or repaired, and only when removed from the can. Aerosol cans use flammable gases as propellants, and when an aerosol can is punctured or otherwise damaged, these gases tend to explode. In cases where the clog cannot be removed from the nozzle, replacing the nozzle with a new one restores the aerosol can's ability to spray. If replacing the nozzle does not fix the issue, then the can is not repairable and should be disposed of as hazardous waste. New cans that appear to be clogged or otherwise do not spray should be returned to the manufacturer as defective.