A tool operated with compressed air or fluid pressure, which expels paint, mortar, etc., through a small orifice, onto the surface being coated. Spray guns are equipment that can spray paint or varnish using air pressure to apply it or spread it on a surface. These guns can be used to paint on any type of surface or substrate, be it metal, wood, stone, clay (ceramics), and porcelain, plastic, glass, or textile.

Within the compressed air sprayer, air jets direct paint to the air nozzle, which atomizes the paint and propels it onto the surface that you're painting. The fluid nozzle controls the paint's delivery, while the needle assembly is what causes the paint to flow.