I did an infusion yesterday and the coat only cured for a hour, but there was no tack after i sprayed it with acetone. I read in another thread that this no longer worked. Why is this not working anymore?

The formulation has been changed to give a longer open time (it can be left longer and still achieve a good bond with epoxy), but a side effect of the change was that it is no longer affected by acetone. 

I have (mistakenly) used acetone to activate some tack after the gel had been left overnight, but this appeared to damage the coating's appearance and leave the surface suffering from pinholes. A decent spray tack will help you out and shouldn't leave any visible markings so long as you don't fo too heavy with it