I’ve just recently shaped and glassed a board using a clark blank with a cedar center stringer and 2 high density colored foam stringers. I used polyester resin in a controlled environment. After I had hotcoated the board i noticed a series of very small air bubbles over the colored foam in both the top and bottom laminations, but no where else. I sanded the board and did a gloss coat but the bubbles came on through again. I have done colored foam stringers before with Epoxy and didn’t have these show up. I just wondered if there is a process or technique that I’m missing to eliminate them when using poly.
I’d suspect you glassed during rising air temps, and the foam gassed some.
Same problem with closedcell eps and such, delayed gassing.
Thanks, that could be the problem, my shaping room I leave at around 62 to 65 and I glass in a room that is temp and humidity controlled at 72. I did move directly from shaping to laminating within a 3 hour period.