Abstract: A conductive filter material or cloth is utilized in spray booths, (1) to eliminate "bleed through" due to electrostatic force to grounded supporting structure, (2) to reduce clogging of the openings between the fibers of the filter material, and (3) to eliminate the possibility of arcing in low humidity and highly volatile solvent conditions.

Abstract: A spray booth has a front movable wall composed of two layers of movable, flexible filter material supplied from a single continuous supply roll located adjacent the floor of the booth. The layers of filter material are composed of a mat of closely-spaced non-woven extruded polypropylene fibers forming a multiplicity of cells and randomly positioned non-woven polypropylene fibers extending from the mat into each said cell to provide sub-cells of sub-micron size openings.

Abstract: A safety power supply system for electrostatic spray coating utilized high frequency (audio or radio frequencies) rectified DC pulses to provide the high voltage between an electrode on a spray gun and work to be coated. A high resistance direct electrical path to ground is provided for all parts of a coating system charged to high voltage during coating operations including highly conductive coating materials. For manual spray guns small electrodes or the atomizing edge of a coating material provides the electrode making it virtually impossible for an operator to come in contact with high voltage charged parts before a charge is substantially bled to ground.

Abstract: An electrostatic spray coating system for spraying conductive coatings such as water base paint has a grounded paint supply sub-system which intermittently supplies conductive coating material to a high voltage sub-system across an air space. An interlock system prevents conductive coating material from being transferred from the grounded sub-system to the high voltage sub-system while high voltage electrical potentials being applied to the high voltage coating material sub-system.