A plating cell for plating a flat substrate, for example, a stamper for a high-density compact disk recording, employs an arcuate sparger to introduce a laminar flow of electrolyte across the surface of the substrate to be plated. In a preferred embodiment, the sparger occupies about 90 to about 120 degrees of arc. A semipermeable weir separates the main plating bath from an anode chamber that contains an anode basket that is filled with nuggets of nickel or other plating material. The plating cell is provided with a backwash flow regime so that impurities and inclusions from the anode chamber are kept out of the plating bath. The substrate can be positioned between vertical and about forty-five degrees from vertical, and can be supported with or without rotation.