a first vibration generator positioned against {TAIL ~ the first container wall} so that, when the first vibration generator is activated, vibrations including a first selected frequency are produced by the first vibration generator and pass into the chemical bath liquid contained in {HEAD ~ the container} at the first container wall; and 
a first vibration generator positioned against { TAIL ~ the first container wall } so that , when the first vibration generator is activated , vibrations including a first selected frequency are produced by the first vibration generator and pass into the chemical bath liquid contained in { HEAD ~ the container } at the first container wall ; and
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH