Abstract: An apparatus for treating the surfaces of formed plastic articles including a plurality of bare metal discharge electrodes connected to a high frequency AC power supply, a counterelectrode disposed in spaced relation to the discharge electrodes for defining a treatment zone therebetween, and an insulation layer mounted in spaced relation to the counterelectrode such that a discreet air space exists between the insulation and counterelectrode for moderating the electrical discharge between the discharge electrodes and counterelectrode and enabling greater control and uniformity in the electrical discharge between the electrodes and counterelectrodes.