A coating method is disclosed that applies a coating to a product in a uniform and controlled manner. The coating method comprises a feeding step, an optional pre-treatment step, at least one coating step, and a finishing step. The coating step(s) comprise the use of a coating material feeder and a coating device. During the coating step(s), a substrate passes through an aperture in the coating device which, includes first and second shell portions, where the first shell portion has a concave surface surrounding the aperture portion. The second shell has a substantially flat face and a mirror aperture that aligns with the aperture of the first shell. The concave surface of the first shell and a groove formed along the perimeter of the aperture collect coating material for coating the object as it passes through the apertures of both shells.