The catalyst solution may include a dye or {HEAD ~ other colorimetric substance} for visualizing the layer of catalyst solution on {TAIL ~ the substrate} 
The catalyst solution may include a dye or { HEAD ~ other colorimetric substance } for visualizing the layer of catalyst solution on { TAIL ~ the substrate }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL