Surface Potential of Insulating Plate Coated by Metallic Paint Spray

Surface potential of insulating plate coated by metallic paint spray has been investigated for improving coating system using an air spray gun. The metallic paint contained aluminum flakes with a thickness of about 30 nm in organic solvent. The paint was sprayed on a test target by the air spray gun at a pressure of 0.2 MPa. The target was an electrically isolated metal plate capacitively coupled with a grounded plate from where the surface potential of the target was measured by an electrostatic voltmeter. It was found that the surface potential of the target drastically rose to the order of kV due to the spray charging of the metallic paint. Such a high target potential in the flammable atmosphere can be serious hazard. For reducing the surface potential, two types of induction charging method were experimentally verified. These methods can effectively reduce the surface potential, leading to more safety coating for insulating targets.