Unpromoted Gelcoat

Anyone had any trouble getting gelcoat to cure? The batch I've been working with took three days to cure when I sprayed the mould last January, and I figured the mould was too cold (room temperature was alright, though). After trimming the hull two weeks ago, I sealed the edges with the same batch of gelcoat, and again it took about three days to dry, this time assisted by heat lamps. I figured it was the air in the foam cores.

When I went to finish the boat off last week by patching a couple of bubbles, I couldn't get the stuff to cure, even with heat lamps on it all night. I mixed a batch in a cup with about 5% MEKP, (from a sealed bottle) and that wouldn't even gel in the cup! I've properly waxed the mixture, so it isn't that either. It's only a gallon can, and maybe 4 mo. old by now.

So, I'm working with the theory that someone screwed up at the factory and sent me unpromoted resin. I've ordered 6% cobalt, DEA, and DMA from the supplier to "promote" what's left in the can. I've got the mixing formulas from "Gelcoat Compounding for Industrial & Marine Products" but I wanted to see if anyone else has had to "cure" a problem like this.

It should be just about impossible for the factory to screw up like this. My consolation is that whoever recieved "promoted" resin for their plural component setup probably had a lot worse problems than I've had.


Matt Turner
Turner Racing Shells Ltd.

 

Looks like you are right. It didn't have promoter or accelerator. I had the same problem with a batch of resin once.