The general spray gun consists of a forged aluminum gun body, a stainless steel needle and a fluid tip, with solvent resistant Teflon seals. Aluminum construction increases the durability of the tool while decreasing its weight. The paint or fluid is usually filled into a 600cc to 1 liter aluminum or PVC container. An intrinsic funnel/strainer holding ring in the container facilitates refilling of the fluid. The spray gun most often functions through compressed air. The gun is linked to air tanks in which air is stored under high pressure. When the trigger is pressed, this air is projected towards the anterior nozzle of the gun at high speeds, taking along the medium to be sprayed.

The spray gun consumes around 15 cubic feet per minute (CFM) of air to generate a pressure of around 29 pounds per Square inch (PSI), resulting in fine atomization of the emitted fluid. A smooth uniform spray is enhanced with a metallic particle control facility. Gravity feed spray guns use the gravitational pull to create a smooth flow with lesser air consumption. The volume and speed of the fluid flow from the spray gun can be adjusted with a diaphragm regulator. The gun has an approximately 1/4 inch air inlet utilizing a big fan pattern for minimal overspray.

The High Volume Low Pressure (HVLP) facility, seen in most spray guns, increases the volume of the air while decreasing the pressure, thereby increasing the spray’s force and also its coverage. A user controlled variable speed fan increases the force and accuracy of the fluid emission from the nozzle. Further versatility is provided with a ‘round to flat’ adjustment for the fan. Precise measurements of the air volume can be determined with a micrometer gauge. Additionally, consistent flow is maintained with regular automatic monitoring of the inlet pressure. Some spray guns have a knob which can be turned to change the functionality from siphoning to pressure-feed. Sometimes, the guns can be converted from non-bleeder to bleeder mode making then compatible with standard and tank-less air compressors.   

Powered spray painters use around 85 watts to create a working pressure of 2000 PSI. These gadgets incorporate a suction lid and a hose that can accommodate around one-gallon paint buckets, accepting the coatings directly from the original can. The carbide piston is designed for durability and a long life. A tapered canister prevents undue wastage of the paint.  

What to look for in a spray gun

Greater control of the flow speed is put into user’s hands with the incorporation of a two speed trigger feature. This is a useful feature as different applications require varying fluid emission strengths. A combination of aluminum and stainless steel in the body construction of the spray gun prevents formation of rust and thus makes the tool compatible with water based fluids. A spray gun that can be cleaned regularly without removal of the micrometer and the other gauges ensures that the gun settings do not require to be changed frequently.

The handle and grip of the spray gun are ergonomically contoured for more comfortable usage and to minimize arm strain when used for long periods of time. Since spray guns work under high pressure, they need to pass stringent international safety parameters. Some reputed manufacturers of general spray guns include Astro Pneumatic, Campbell Hausfeld, Grip, Mechanics, Porter Cable, SATA, and Sharpe.