{TAIL ~ A dye} or other colorimetric substance may be added to the catalyst solution to allow for visualization of the amount and location of {HEAD ~ catalyst solution} on the substrate 
{ TAIL ~ A dye } or other colorimetric substance may be added to the catalyst solution to allow for visualization of the amount and location of { HEAD ~ catalyst solution } on the substrate
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 HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH