I was attempting to make a mould for a car hatch/boot and ran into what i presume are a couple of problems in that i applied the gel coat, catalysed at 1.5%,, after reading the instructions that indicated you should leave till tacky or overnight i was surprised that in under two hours the gel was dry to the touch in places with no tack at all.  At this time i did what was probably the wrong thing and decided to put the coupling coat on, which again went past the tacky stage in places before i'd noticed so i put the reinforcing on.