Abstract: A powder coating composition comprises a mixture of first and second component powder coating compositions which are separate, preferably widely separated, in a triboelectric reference series indicative of the extent to which powder coating compositions may be distinguishable from one another when electrically charged. The mixed powder coating composition is especially suitable for coating articles having recessed portions. A quantitative basis is given for determining the separation of the individual component compositions in the triboelectric reference series, and preferred minimum separation criteria are given.

Abstract: A powder coating composition comprises a mixture of first and second component powder coating compositions which are separated, preferably widely separated, in a triboelectric reference series indicative of the extent to which powder coating compositions may be distinguishable from one another when electrically charged. The mixed powder coating composition is especially suitable for coating articles having recessed portions. A quantitative basis is given for determining the separation of the individual component compositions in the triboelectric reference series, and preferred minimum separation criteria are given.

Abstract: A process for forming a coating on a conductive substrate, which comprises establishing a fluidized bed of a powder coating composition, in which the mechanism for particle charging is tribostatic charging immersing the substrate wholly or partly within the said fluidized bed, applying a voltage to the substrate for at least part of the period of immersion, whereby particles of the powder coating composition adhere to the substrate, withdrawing the substrate from the fluidized bed and forming the adherent particles into a continuous coating over at least part of the substrate. The process enables the coating of substrate areas which, because of the Faraday cage effect, are inaccessible in conventional electrostatic coating processes, and also enables the formation of thinner coatings than are obtainable by conventional fluidized-bed processes.

Abstract: A power coating composition comprises at least one film-forming polymeric material and has dry-blended therewith two or more dry-blended additives selected from solid, particulate, inorganic, water-insoluble materials which may be ceramic or mineral materials and/or may be oxides, mixed oxides, hydrated oxides, hydroxides, oxide-hydroxides or oxysalts of metals and metalloids, at least 95% by volume of the powder coating composition having a particle size not exceeding 50 microns.