How a Spray Gun Works

Spray Gun

A pneumatic spray gun, which is most often used for painting cars or other items, is a relatively complicated piece of machinery. The purpose of the spray gun is to achieve a consistent and even coat of paint that isn't achievable in any other way. The spray gun works by converting the liquid paint into atomized droplets that spray like a mist. The guns do this through a variety of methods, but the component parts all serve roughly the same function, no matter which type of gun is being used.

Parts

The most important part of a spray gun is the reservoir. It is where the paint is held, and it comes in a variety of sizes, though it usually holds about a pint of paint. The air cap is the spot on the end of the spray gun's barrel through which the paint is blown. The air cap defines the pattern that the spray gun paints in, and it atomizes the paint based on the pattern of holes. The fluid needle, which is a tapered shaft attached to the spray gun's trigger, is another important part of the spray gun. When the trigger is pulled, the fluid needle opens up the spray gun's passageway, widening out further the deeper the trigger is depressed.

Process

The paint reservoir is first filled with paint. Once it's attached back to the spray gun, the air cap is adjusted so that the "fan" (the pattern that the paint is sprayed in) is in the pattern that the painter wants. As the trigger is pulled, the fluid needle opens up the shaft inside the spray gun. The wider the pathway is, the more paint is allowed to mix with the air, and the more paint will come out. Making sure that the nozzle is properly adjusted, and that the trigger is depressed in the proper distance, requires a steady hand and practice to get right.