My next decision is when to use epoxy primer or urethane primer, over my superbuild and featherfill pimers. I'll use some of my 2 gallons of epoxy on the bare frame, but the rest will go onto the fiberglass parts. I've also got 5 quarts of urethane available, but I'm worried that I'll spray some part with it and find a spot that needs some glazing putty to make a small repair. AFAIK, even the u-pol glaze can't be applied to the urethane, but it can go over epoxy. U-pol glaze can be applied to "OEM paints", according to the literature. The advantage of the urethane primer is a much shorter drying time to be ready to sand.

As already mentioned, the majority of the high build products end up on the floor, just like a whole lot of the filler I apply. Their big advantage is that you're sanding the same product over the entire surface and not having to feather edge or sand across materials that sand away at different rates. Gel coat and fiberglass both sand away a lot slower than filler or primer. If you hit a high spot of gel coat or fiberglass, you either need to quit sanding or deliberately sand the area lower and reapply some high build primer to avoid different material removal rates.

I've found blocking all of the bulbous areas somewhat challenging, but the soft-sanders blocks I'm using really help. The flexible yellow blocks work great on all of the curved areas.

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