How to Adjust Spray Guns for Optimum Finishing
There are a few ways to control the material and atomization air supplied to a spray gun. However, certain methods allow for greater precision of control while other methods allow for broad based control. Ultimately you will most likely use a combination of methods to control fluid delivery and atomization air to a spray gun, but by thinking through where you coarse and fine tune a spray gun you can achieve better finish qualities.
First, think about gross adjustments to your spray gun. Primarily this will mean adjusting the amount of fluid delivered (if using a pressure tank) and the atomization air supplied to the gun. If you are using a gravity feed or siphon feed spray gun the gross supply of atomization and fluid delivery is controlled by the same source, the shop air that is fed to the gun. Therefore if you are using a gravity or siphon feed gun your coarse adjustment will be done by adjusting the shop air supplied to the gun at an air regulator. The air regulator will allow you to control the air to the gun from the shop air or compressor which in turn will dictate the amount of fluid and atomization air supplied to the gun. In contrast, a pressure fed spray gun will allow you to adjust the fluid delivery and atomization air independently. Typically to get the correct fluid pressure with a pressure feed system you adjust pressure up until a steady flow of material is exiting the tip of the spray gun and is able to travel a few feet in a downward arc. You then would apply the desired amount of atomization air (12 – 16 psi typically) from the pressure tank as well. All of this can be done at the pressure tank. This second set of controls is the reason why a pressure tank outfit allows for finer control of finishing, with gravity and siphon feed you only control material and air at the gun itself instead of at the pressure tank and gun itself.