“"bog" filler will never "go off" faster than gel coat. the resin content in the "bog" reacts at exactly the same rate as the resin content in the gel coat. Why "bog", at times gels faster than the same equivilent volume/weight of gel coat is for just that reason, ie the same volume of "mixed" bog to the same volume of gel coat. When you calculate the volume of catalyst for filler, you must realise that there is a much smaller percentage of resin in the filler than in the same volume of gel coat, so that the catalyst should be calculate for the volume/weight of actual resin in the mix and not for the entire mass.”

If that was the case then Epoxy “bog” would not kick off faster than an equal amount of resin since the proportions of resin to hardener are at fixed ratios for epoxy resins…but it does…the added fillers probably keep the resin from losing heat as quickly when it exotherms during the curing process. Which in turn, cases the reaction to be accelerated.

Bob