: Oops! I may not have been clear enough in my description. I'm looking at the
: other end of the process - weave fill. I'm liking the effect of the
: thicker epoxy, and looking for increased viscosity for a useful period of
: time.

That's risky because there really is not a "useful period of time" between what you are looking for and "too late" - and it varies by the size of the batch you mix and temperature. Something you might want to consider is applying the fill coats in a colder environment. The lower the temperature, the thicker the epoxy - at least with MAS. You just have to be carefull not to let the boat warm up until the epoxy starts curing - could be up to 8 hours if its really cool. If it starts warming up to soon, the epoxy will thin from the warmth, and start running - then you have a mess. I have not actually tried this, but over the past couple of winters I had the opportunity to see how epoxy reacts to different temperatures.