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