{HEAD ~ A dye} or 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
{ HEAD ~ A dye } or 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
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH 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