Electrostatic spraying is the process of applying a charged liquid to a surface. A charge is induced on the liquid droplets as they are formed, just before exiting the sprayer nozzle. When the charged droplets approach a surface, they induce an opposite charge on the surface which then attracts the charged droplet to the surface. The charged droplets also repel each other, preventing them from coalescing into larger droplets. The repulsion also allows the droplet to uniformly cover surfaces. Droplets can even be attracted to the backs of surfaces regardless of the direction of spray, enabling them to “wrap” around a range of surface types including curved surfaces. In this respect, electrostatic spraying can be considered an “active” application technology in that liquid droplets are attracted to surfaces. With normal or non-charged “passive” spraying, the coverage of surfaces is determined by the direction of spray and where the droplets fall based on the effect of gravity, and may result in uneven surface coverage.
The electrostatic spraying process has been used for more than 60 years in painting and agriculture applications.1In agriculture, electrostatic sprayers are used for the efficient application of pesticides to plants, to help treat the “hidden” undersides of leaves that pesticides applied using regular non-charged spray applications are unable to reach. The more uniform coverage of the fine electrostatically-charged droplets also allows for better coverage of surfaces with less pesticide compared to application with a non-charged sprayer.