Several spraying techniques are used for wet painting. An air sprayer, for example, operates with pressurised air supplied by a compressor that forces the paint through the nozzle. Airless paint sprayers do not use air to spray the paint. Instead, they use a motorised pump to pressurise the paint and push it out through the nozzle. The tiny particles of paint emitted from the sprayer penetrate well into pits and crevices on the surface, which is sealed with a uniform thick coating.