Electrostatic Painting
An electrostatic paint spray system is a highly efficient technology for the application of paint to a specific metal item such as a fence, railing or metal furniture. Negatively charged atomized paint particles and a grounded metal item create an electrostatic field that draws the paint particle to the metal, minimizing overspray.
For this technology, an ionizing electrode, typically located at the paint gun atomizer tip, causes paint particles to pick up additional electrons and become negatively charged. As the coating is deposited on the metal, the charge dissipates through the ground and returns to the power supply, completing the circuit. The electrostatic field influences the path of the paint particles. Because the charged particles are attracted to the grounded metal, overspray is significantly reduced. Paint particles that pass the metal can be attracted to and deposited on the back of the piece. This phenomenon is known as "wrap."
The transfer efficiency is the percent of sprayed paint that is applied to the metal. The typical transfer efficiency for an electrostatic paint spray system is 75%.
Paints used for electrostatic painting must be formulated with polarizable solvents. Personnel responsible for ordering the paint should coordinate with the supplier/manufacturer to ensure that they obtain the proper formulation.
No new wastes are generated when a conventional paint spray system is converted to an electrostatic paint spray system. Significant reductions in waste generation are achieved due to the electrostatic system’s increased transfer efficiency.
Electrostatic paint equipment is available in three basic types: air atomized, airless, and rotating discs and bells. High-speed discs atomize the coating more finely than air atomization and direct more paint to the target. This technology is particularly efficient for the application of difficult to disperse, high-solids paints. However, the Faraday cage effect is generally greater with rotary atomizers than with air or airless types. Rotary atomizers, therefore, may not provide adequate coverage for complicated surfaces.