Abstract: A method and apparatus for processing a substrate by electrochemical mechanical planarization and electrochemical mechanical plating is disclosed. Included are various embodiments of a processing pad article comprising an open cell foam subpad that is adapted to retain an electrolyte while encountering centrifugal motion, and simultaneously provide electrical and/or abrasive contact to a feature side of a substrate. Also disclosed is a platen capable of holding an electrolyte during processing at a desired RPM, then releasing the electrolyte centrifugally at a higher RPM. The release is actuated by an operator or by centrifugal force.