Spray guns are most suited to spraying cellulose paint but can be used for emulsion and oil-based paints as well – sometimes, these require a different nozzle.

Most spray guns can also be used for spraying insecticides and wood preservatives. In all cases, cleaning out the gun thoroughly after use is essential.

In order to get a good finish, a spray gun has to produce a good spray pattern which is broad and even and fades away evenly (and quite sharply) at the top and bottom enabling you to pass along the surface in only slightly overlapping bands. Fan-shaped nozzles tend to produce a more even spray than the usual round ones. The paint must be properly atomised, that is have small evenly sized particles which just blend together to form a uniform coat of paint. How well a spray gun atomises the paint depends partly on the design of the gun. but it is also affected by the viscosity (thickness) of the paint being used the thicker the paint, the more difficult it will be for the gun to break it up into small particles. If the paint is too thin, it may not cover the surface properly.