The principle of function is determined by the requirements placed on the booth, which are: - The protection of the coating process from external influences, combined with keeping the area around the booth clean - The powder recovery - The avoidance of an explosive powder/air mixture inside the booth An efficient exhaust air system is used to keep the area around the booth clean and to prevent explosive powder/air mixtures. The fan in the After Filter extracts the air from the inside of the booth through the cyclone and afterwards through the filter elements. The air stream created thereby, flowing from the outside to the inside of the booth, prevents powder escaping to the environment of the booth, so that keeping the area around the booth clean is guaranteed. The maintenance of the air flow prevents as well the creation of dangerous powder/air mixtures. The powder recovery takes place by the powder separation in the cyclone separator during operation.