a bowed framed membrane is disclosed for use in automated direct blot electrophoresis and subsequent membrane process steps to develop a chemiluminescent image of the resultant blot of selected fragments and to detect that image . a frame made from a thin rigid plastic plate such as polyethylene is provided with a window . a membrane covers that window and is bonded on two opposing sides only while the frame is held in a bowed condition . the membrane is maintained under tension during processing by the bowing permitting processing at the elevated temperatures used in molecular biological procedures without loss of flatness . processes for preparing such frames and various utilities are also disclosed .