An apparatus for charging a photoconductive surface to a substantially uniform potential in a printing machine having a cleaning station (79) for cleaning the surface and an exposure station (35) for exposing the surface to a light source includes a first mechanism (34) for charging the surface to a substantially uniform potential of a first polarity after the surface is cleaned at the cleaning station (35). The apparatus further includes a second mechanism (36) for charging the surface to a substantially uniform potential of a second polarity opposite to the first polarity after the surface is charged to the substantially uniform potential of the first polarity by the first charging mechanism (34) and before the surface is exposed to the light source at the exposure station (35). Similarly, a method of charging a photoconductive surface to a substantially uniform potential in a printing machine having a cleaning station (79) for cleaning the surface and an exposure station (35) for exposing the surface to a light source, includes the steps of (1) charging the surface to a substantially uniform potential of a first polarity after the surface is cleaned at the cleaning station (79) ; and (2) charging the surface to a substantially uniform potential of a second polarity opposite to the first polarity after the first polarity charging step and before the surface is exposed to the light source at the exposure station (35).