Another frustration is that the fiberglass / filler has already started to move. When I picked it up from paint it was perfect, now I can already see some of the joins that are appearing as the filler sinks and fiberglass moves. One of the annoying things with fiberglass is that in heat it still moves about even after its cured
Use to have this problem also.
I was curious why this was happening because you can buy blocks of the same foam and it didn't do this.
Well after reading the instructions on the cans of the foam it said allow min 24 hours to cure(depends on air temperature). I was starting to cut and form it after about an hour that it was poured.
Letting it cure for 24 hours helped alot but I still got small pockets that showed signs of the foam reacting with the filler.
I'm using casting resin now to seal the foam, I apply that(by brush), then sand it smooth. If I break through to the foam during sanding it I'll apply another coat of the casting resin over the foam that is exposed and it gets another sanding. if needed I use a finishing putty to fill in the imperfections.
If no sanding is required after the casting resin is applied the finish of the resin is a smooth glossy finish.
Another thing about the resin is it cures fast. Starts to setup in about a minute. There maybe other brands that cure slower but I like the fact that it cured fast. Just don't mix more than you can brush on within the time limit.
Resin viscosity starts out thin so it flows into the air pockets of the foam easily then as it cures it starts to thicken. Once it got to the consistency of syrup I stop applying it and let it continue to cure
Cures a little different than laminating resin. It doesn't gel up like laminating resin but just continues to get thicker till it is fully cured.
So far I've had good results with it not reacting with the foam.
Sorry I didn't get this info to you sooner.
I see you like that aluminum tape*laugh* Works great for me also