Spray Painting Terminology

As with any precise task that uses a specialized tool for its accomplishment, spray painting of automobiles has developed a terminology of its own to ensure that precise information about how to carry out various painting operations can be transmitted easily from one person another. The absence of a specialized terminology usually has the effective making explanations long-winded and vague, so it pays at this point to memorize a few terms used to describe the different parts of the spray gun and spraying equipment. The vocabulary is mostly straightforward and easy to recall.

• The handle is the pistol grip that your hand wraps around to hold the spray gun while you use it. The air hose connects to the bottom of the handle, and an air passage runs through the handle and up into the workings of the gun. The trigger of the gun is also part of the handle assembly.
• Two knobs above the handle on the back end of the spray gun are the air-adjusting knob, also known as the air micrometer, and the paint-adjusting knob, which also goes by the name of the material control. These two knobs can be turned by the operator to add more or less air and more or less paint flow to the spray.
• A long, slender valve inside the spray gun is known as the paint needle valve. This is controlled directly by the paint-adjusting knob or material control, and regulates the flow of paint out of the nozzle. There is a second needle valve, the air needle valve, which changes the air flow when the air micrometer is adjusted. The exact arrangement of these needle valves is determined by the manufacturer’s specific design.
• The front end of the spray gun is known as the nozzle, while the round, often brass, cap at the very tip of the device is the air cap, which is held on by the air cap retainer. This has a central orifice where the paint emerges, and two flanking orifices that produce thin jets of air parallel to the central orifice. There are also two wing ports, also called horn ports, which are small air orifices mounted on jutting wings or horns on the air cap, so that their jets of pressurized air are directed diagonally into the stream of paint, just a small distance beyond the main orifice.
• The paint is held in a paint cup – occasionally known by other names, but mostly by this title. The paint cup can be mounted above or below the nozzle, depending on whether the spray gun is a regular or an HVLP model. Regular paint cups have a special vent port through which air is sucked into the cup while paint is sucked out upwards, while HVLP paint cups are designed to maximize their gravity feed efficiency.