Abstract: An electrostatic powder coating booth has double walls which can be evacuated to hold replaceable cover foils thereagainst so that, for a color change, a contaminated stretch of foil can be replaced by a fresh stretch of foil.

Abstract: The inside of a sleeve is positioned over a nozzle having an elongated groove opening immediately at the region of the sleeve to be striped. The sleeve surrounding the nozzle is given a predetermined potential level. A stream of particles is introduced into at least one end of the groove in a direction at least generally parallel to the groove and to the region to be striped. The particles are charged relative to the potential level of the sleeve such that the particles are attracted to the sleeve. A stream of air is also introduced under pressure into the opposite end of the groove in generally the opposite direction. The countercurrent thus produced deflects the stream of powder so it projects generally radially from the nozzle groove, thickly coating the strip region at the seam. The region is the seam of the sleeve which is to be made into a three-part can, in which case the groove is longer than the sleeve.