apparatus and method for treating the interior surfaces of hollow plastic objects to improve their adherency to and compatibility with another component , such as polyurethane foam . the invention consists of creating a vacuum in the object and drawing a conductive gas inside the object . a pair of electrodes are spaced apart from each other , and a source of electricity is provided thereto of sufficient intensity to produce an electrical discharge across the gap between the electrodes when an object is in the gap between the electrodes . the electrodes are arranged with regard to the size and configuration of the object to provide ionization of the conductive gas inside the object to surface treat the inner walls .