Spray painting is an excellent method of applying paints and other coatings to broad surfaces quickly and evenly. Using spray painting equipment is also a fast method of achieving a quality finish that is difficult to replicate by applying paint with paint brushes and rollers.
Spray painting also allows application of much thicker coats than is possible when applying paint with a paint brush or roller.
Spray painting equipment can usually be classified as either air atomising spray guns or airless atomising spray guns or pumps.
Air atomising, often referred to as conventional spray equipment, atomises the paint stream exiting the fluid nozzle of a conventional spray gun by directing a stream of compressed air onto this stream of paint as it exits the gun. This compressed air from the air horns on the air cap of the spray gun break the steam of paint into a fine mist which is "carried" onto the surface. Generally there is a higher amount of overspray from conventional spray guns as opposed to airless spray painting.
Airless spray guns atomise a stream of paint exiting a very small nozzle or tip at high velocity. the high velocity on exit from the tip breaks the stream, atomises, into a fine spray and carries the paint particle to the surface. A similar effect occurs with a garden hose and a spray nozzle. As the spray nozzle on a garden hose is adjusted to reduce the flow of water the stream of water become a spray instead of simply pouring from the end of a hose without a nozzle fitted.
Airless spray units are very effective for covering broad areas to be painted quickly. Paint usually does not need to be thinned at all when sprayed with a quality airless sprayer.