Most painters use a regulator...
Most painters use a regulator or simple choke valve at the gun to provide the final airflow adjustment. Here we have a simple choke valve, which provides a variable restriction to the gun.
These modern guns have become highly refined and offer excellent atomization of the paint fluid, with restrained overspray and a more defined paint pattern, cutting substantially on the paint lost to the atmosphere, reducing paint material quantity requirements in the process. Most of this equipment is designed with a top-mounted paint supply reservoir cup, rather than the bottom-mounted cup typically used with traditional suction-feed spray equipment. This design also cut on waste by virtually eliminating the leftover paint in a suction-feed cup.
A skilled painter can achieve excellent results with a wide variety of quality spray equipment, and as a general rule, the more expensive spray gun models offer a finer finish quality. The professional-grade equipment is typically better serviced by the paint supply dealers that carry a particular line of spray guns, with accessories such as air caps and fluid nozzles with specific orifices to handle different materials such as paint or heavy primer. Generally, the pros will use dedicated paint guns for primer, paint, and sometimes even clearcoat. Another specialty gun that is worth considering is a small touch-up gun, which can be incredibly useful for tighter areas or small self-contained jobs such as the engine bay or jambs. A novice painter can do well with a single high-quality general purpose gun. When it comes to successfully applying paint, experience and familiarity with the specific spray equipment is nearly as important as the specific equipment itself.
For many years, conventional...
For many years, conventional suction-feed guns such as this DeVilbiss JGA-502 were the standard of the automotive refinish industry. Though these guns can still produce exceptional results, these days they have been supplanted by modern equipment that produces much less overspray, saving material and reducing environmental concerns.
No matter what the type of paint gun, it's virtually a requirement to have some sort of device mounted at the air inlet to regulate the airflow and pressure through the gun. These units can be a true regulator, or a simple adjustable choke-style restrictor, favored by many painters. The regulator or choke at the gun should work in conjunction with the main supply regulator, which is normally set at somewhat higher than the required pressure. A pressure gauge is usually, but not always, incorporated at the gun regulator or choke.
There are a variety of consumable supplies that should be on hand whenever a refinish job is contemplated. Some of these are mandatory, while others are added insurance to guard against problems and to achieve a professional result. The most basic of these supplies are sticks and strainers, used to stir and filter the liquid paint. These come as wooden paddles and disposable paper and gauze filters, which are often provided free of charge as a courtesy of the paint supplier. Another handy item for use while mixing the paint components is a graduated mixing cup. Usually these have multiple ratio scales corresponding to the common mixing ratios for the product being used. Similarly, measuring sticks are another alternative, this time with the ratio graduations being marked along the length of the mixing stick. Paint gun liners are another category of consumable supplies, providing a disposable lining for the paint gun cup, helping to ensure cleanliness and easing clean-up after the job is done.
Modern paint guns are almost...
Modern paint guns are almost universally the High Volume Low Pressure (HVLP) type, which are often mandated by environmental regulations. Typically, these guns are gravity-feed types with the gun cup or reservoir mounted to the top of the unit. When it comes to HVLP spray equipment, the finish quality offered is usually proportional to the cost of the unit.
Also fitting the category of a consumable supply are disposable moisture separators that are mounted right at the air inlet of the spray gun. Consider these a last line of defense against moisture droplets contaminating the paintwork. While on the subject of consumable supplies, don't neglect the air filtration on the paint booth itself. While the filters are designed to trap debris and dust, dirty filters can actually become a source of these airborne contaminants which can quickly damage an otherwise perfect paint job. Make sure the filters in the facility are clean, and replace them if necessary.
Personal Protection Equipment
An area of required equipment that's often overlooked, but which may be the most important of all, is safety and personal protection. While we've all seen old-timers spraying various products with just a dust mask, if anything at all, many of today's paint products can be highly hazardous to your health, whether inhaled or absorbed through your skin. Various materials have differing levels of hazard and required precautions. It's important to be aware of these requirements and take the recommended precautions.