Electrical characterization of a charged-workpiece grounded-sprayer electrostatic painting system

In situations where paint resistivity is low, as for waterborne paints, it is not possible to use conventional electrostatic painting systems without isolating the sprayer, the fluid-handling system, and the paint containers. An alternate technique is to apply high voltage to the workpiece and ground the sprayer. The authors evaluate the electrical characteristics of such a system and compare them to those of the conventional electrostatic spraying system. It is shown that a charged-workpiece, grounded-sprayer system will achieve a transfer efficiency comparable to that of a conventional system. The results predict an enhancement in the film build-up along curved surfaces and strong wrap-around. These predictions have been confirmed experimentally. The analysis indicates that there will be no improvement in the paint deposition on recessed surfaces.<>