| abstract |
A process for forming a coating on a conductive substrate, including the steps of: establishing a fluidised-bed of a powder coating composition, thereby effecting tribostatic charging of the powder coating composition, the fluidised-bed including a fluidising chamber at least a part of which is conductive, applying a voltage to the conductive part of the fluidising chamber, immersing the substrate wholly or partly in the fluidised bed, whereby charged particles of the powder coating composition adhere to the substrate, the substrate being either electrically isolated or earthed, withdrawing the substrate from the fluidised-bed and forming the adherent particles into a continuous coating over at least part of the substrate. The process offers advantages in terms of coating substrate areas which, because of the Faraday cage effect, are inaccessible in conventional electrostatic powder coating processes, and also enables the formation of thinner coatings than are obtainable by conventional fluidised-bed processes. |