an automatic production apparatus for processing semiconductor wafers which include a rotor rotatable about a substantially horizontal axis where the rotor includes a removable carrier capable of holding a plurality of semiconductor wafers or glass photomask plates and a plastic - coated bar for retaining the semiconductor wafers in the carrier when inverted at low rpm &# 39 ; s and a plurality of spray nozzles for providing the processing medium and a recessed drain for removing the expended processing medium . a timing device sequentially controls the processing functions and structure is provided to accomplish these functions .