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