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