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