RE: Fiberglass with Polyurethane
G''Mornin, Irish.
I usually glass in the wing joints with about six inches of glass, three inches per side, of light glass, but use epoxy resin. We had a training session at one of our meetings, more of a show-and-tell, in which our club Pro (one of them, anyway) did a demonstration of glassing the wing joint. He said that once the resin soaks into the glass, to scrape it off with something..he used an ordinary playing card (since we live near the Casino''s of Atlantic City, we can get playing cards at a discount.. often for free.. discarded, once used packs of cards). One scrape, throw the card away.. next card and next scrape.
Well, he said to scrape it down until it looked like it was dry. Then let it set. After that, we sanded the joint down smooth to remove the remaining sharp edges, then just applied the covering right over it. And, it stuck. I don''t recall what we used, Ultracoat, Monocoat, not exactly sure, but it stuck just fine.
Hope that helps a bit.
Dick.