A method and apparatus is provided for removing material from the edge of a disk. In one embodiment, the edge of the disk is contacted with etchant via an etchant containing swab or trough (which may contain one or more transducers) and is rotated such that successive portions of the disk edge are scanned through the trough or past the swab. To prevent etchant from contacting the major surface of the substrate, and/or to prevent excessive etching, the edge of the disk is contacted with a rinsing fluid (e.g., a rinsing fluid nozzle or a trough filled with rinsing fluid). In a further embodiment material such as residue or particles may be removed via a trough containing sonically energized rinsing fluid.