| There are several key factors that must come | | | | means of atomizing the coatings. When the gun is |
| together in order to use electrostatic guns | | | | triggered, the high fluid pressure is allowed to escape |
| effectively. First you must select the right | | | | into the atmosphere through a tungsten carbide tip |
| atomization technology for your coating application | | | | that is cut to form an elliptical spray pattern. The size |
| needs. There are several electrostatic atomization | | | | of the pattern and the amount of fluid leaving the |
| technologies to choose from. The oldest and | | | | gun are controlled by the tip. The viscosity of the |
| probably most common are the air spray | | | | coating and the fluid pressure used also affects the |
| electrostatic guns. These guns use compressed air as | | | | application rate. |
| their primary and sole means of atomizing the | | | | In general, airless technology does not provide the |
| coating. These guns are most commonly used in | | | | same level of atomization as air spray or HVLP |
| applications that require a "Class A" automotive finish. | | | | electrostatic guns but they work well for some |
| The guns offer a lot of control at the gun such as | | | | coatings, especially when spraying large products at |
| fluid flow by use of the fluid needle adjustment knob | | | | high rates of speed. Tip plugging can be an issue |
| and fan control through the use of the fan | | | | when spraying materials that contain an aggregate |
| adjustment knob. In addition, the amount of fluid can | | | | such as silica or zinc. Air-assisted airless electrostatic is |
| be controlled by how far back the operator pulls the | | | | a hybrid version of the airless electrostatic and the air |
| trigger. This is referred to as "feathering" the gun. | | | | spray electrostatic. These guns use both fluid |
| The main source of fluid control is determined by the | | | | pressure and air pressure to atomize the coating. |
| fluid pressure from a low-pressure pump, the air | | | | Pumps are needed to create the fluid pressure. Since |
| going into a pressure pot or by a fluid regulator | | | | these types of guns use lower fluid pressure than |
| mounted near, or in the spray booth. The viscosity | | | | airless and less air pressure than air spray, they can |
| of the coating and the size of the fluid nozzle also | | | | offer companies a good compromise between the |
| affect the fluid flow. Although air spray electrostatic | | | | speed of an airless and a finish quality closer to the |
| guns have great atomization, they are also the least | | | | air spray electrostatic. The best part is that this |
| efficient of the electrostatic guns. This is due to the | | | | technology is usually more efficient than either the air |
| potential use of high air pressure to atomize the | | | | spray or the airless electrostatic guns. In some cases |
| coating. The use of high air pressure can defeat the | | | | they are even more efficient than the HVLP |
| electrostatic attraction by forcing the charged | | | | electrostatic guns. |
| particles of paint past the part or by creating | | | | However, air assisted airless electrostatic guns do not |
| excessive bounce back or overspray. | | | | offer the same level of control at the gun as the air |
| A variation of the air spray electrostatic gun is the | | | | spray or HVLP electrostatic guns. This is because the |
| HVLP electrostatic gun. The gun operates almost | | | | fluid pattern cannot be fully adjusted from very |
| identically to the air spray gun except that it uses | | | | narrow to very wide without changing the tip. Also, |
| less atomizing air pressure. Instead, the gun uses | | | | like the airless electrostatic gun, the operator cannot |
| more cubic feet of compressed air or CFM. The | | | | feather the gun. This could be problematic when |
| result is a softer spray pattern which lowers the | | | | spraying very complex substrates where the |
| velocity at which the paint particles travel. This allows | | | | operator needs that kind of control at the gun. Tip |
| for more of the charged particles to remain in the | | | | plugging can also be an issue with some aggregate |
| electrostatic field which helps to improve transfer | | | | filled materials. |
| efficiency. Like any HVLP gun, some coatings may be | | | | The most efficient manual electrostatic spray gun is a |
| too viscous or the application rate may be too high, | | | | hand held rotary atomizer. These guns use centrifugal |
| which may make it difficult for the HVLP electrostatic | | | | forces and a very high voltage electrostatic field to |
| gun to provide high productivity and acceptable finish | | | | atomize the material. Since there is no atomizing air |
| quality for some applications. In addition, HVLP guns | | | | the paint particles travel very slowly through the |
| usually require more CFM which can lead to increased | | | | electrostatic field. The result is very high transfer |
| electrical costs for compressed air. | | | | efficiency. However, the gun puts out a doughnut |
| For the application of very viscous materials or for | | | | shaped spray pattern which does not work well for |
| very high application rates, some manufacturers use | | | | most production finishing applications and is used |
| airless electrostatic guns. These guns use pumps to | | | | mostly for the on-site refinishing industry. |
| create very high fluid pressure which is the primary | | | | |