Conversely, a catalyst solution consisting of 0.25% by volume of catalyst engenders {TAIL ~ an approximate 15 second interval} to {HEAD ~ completion} of hardening 
Conversely , a catalyst solution consisting of 0.25 % by volume of catalyst engenders { TAIL ~ an approximate 15 second interval } to { HEAD ~ completion } of hardening
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH