Abstract: To eliminate the manual handling of individual articles associated with loading and unloading conventional treating apparatus, a plurality of articles are simultaneously treated in the carriers which are used for batch handling prior to and subsequent to the treating operation. In a disclosed embodiment, wafer-shaped articles are held in mutually spaced substantially parallel relationship in a plurality of slots in a first carrier having an open face through which the wafers can be inserted and removed. The open face of the first carrier is abutted to the open face of an empty second carrier having at least a corresponding plurality of slots, such that the slots of the first carrier are aligned with the slots of the second carrier. The abutted carriers, with the wafers contained therein, are submersed in a treating medium and rotated about an axis running through the abutted faces of the carriers.