Spraying with manual electrostatic applicators has several advantages. Electrostatic guns have very high transfer efficiency which means less money spent on paint, less VOCs, less cleanup and faster production. They also provide excellent finish quality.
Solventborne coatings, including low, medium, and high solids coatings, enamels, lacquers, and two-component coatings can be trusted to provide tough, durable finishes. These coatings are often applied with the following air spray or air-assisted airless technology.
Air Spray Electrostatic Spraying uses a low-pressure fluid stream that is mixed with compressed air at the aircap to atomize material in a controlled manner. It is used for the application of low to medium viscosity fluids for products requiring a high quality, Class A or decorative finish.
Air-Assisted Airless Electrostatic Spraying uses a high-pressure fluid supply for atomization and compressed air at the cap for pattern control. Air-assisted airless electrostatic spraying solves many problems that arise with the use of high-viscosity and high-solids coatings, and other issues associated with heating and using higher fluid pressures to aid in the atomization of more viscous materials.
All of these electrostatic applicators charge material particles as they pass or contact an electrode to achieve higher transfer efficiency. They rely upon the attraction of opposite electrical charges. The material is electrostatically charged as it passes through an electrostatic field produced between the electrode on the front of the gun and a grounded object. The charged particles of the material are attracted to the grounded (neutral) object and form an even coating. The charged material will then wrap itself around the object, which will increase surface space that is coated. Because of this “wraparound” effect, electrostatic applicators are especially suitable for coating tubular products. Many parameters determine the efficiency with which the material can wrap around the surface.
- Polarity of the coating
- Voltage potential of the spray gun
- Air velocity in the spray booth
- Efficiency of the ground
To determine the correct coating to use in an electrostatic gun, you must consider its “resistivity”. The materials, solvents, and reducers used in the manufacture of the coatings determine the resistivity of the coating. This can be measured with a paint probe meter which measures megohms per centimeter of resistance. The best electrostatic results are achieved when the resistivity of the coating is between 25 and 50 megohms per centimeter. Getting the paint formulated from the manufacturer for electrostatic use is typically the best solution.
While solventborne coating systems still remain the benchmark for overall performance, application and appearance characteristics, Waterborne materials are growing in popularity because of more stringent air quality regulations. They contain and emit less organic solvent into the atmosphere while providing certain refinishing benefits and offering lower toxicity.
Waterborne materials have low resistivity, therefore, require different handling when spraying with electrostatic guns. Traditionally, spraying waterborne materials with manual air spray applicators required either conventional air spray guns or for electrostatics, an isolation system. Both methods have their disadvantages. Conventional air spray guns do not deliver the transfer efficiency or wrap that electrostatic spraying delivers. In addition, if electrostatic automatic applicators are used in the finishing process, color match can be difficult because of the various material types used in certain applications. While isolation systems address these issues, they are difficult to work with in a high production facility.
The new alternative for spraying waterborne materials with electrostatics is an external charging electrostatic applicator. The external charging electrostatic gun can be connected to a circulation system or a pump system. The waterborne material is charged as it is exiting the gun through an electrostatic field. The external charging electrostatic gun eliminates the need for an isolation system.
In addition, waterborne electrostatic guns have the advantage of delivering higher transfer efficiency and higher productivity then conventional air spray guns. Because of these cost saving benefits, smart consumers are replacing existing conventional air spray guns with waterborne electrostatic spray guns on a circulation system.
Overall, the difference is clear. Electrostatic guns not only provide better finish quality compared to conventional air spray and HVLP guns, but they also reduce VOC emissions and improve production speeds. Consider the benefits of switching to electrostatic technology before purchasing another gun for yourself, or for your business.
See how much you can save when you replace your conventional air-assist or HVLP gun with a Pro Xp Series spray gun.