Sealing EPS technique for microballoons/resin

[stoneburner]

xps pre-lam epoxy sealer coat?

In air plane garage builder world, guys used to sealer coat the xps “spyder foam” with an epoxy slurry, a 50/50 mix of epoxy/microsphere then most laminate directly on this fresh coat. You can add pigments for more opaque, you can add cabosil to gelify the slurry, easier to squegge “in” the core. 

EPS sealing

Epoxy microsphere “dry mix”, = 1 volume resin, 4 to 5 volume micro. A bit tricky to mix, add micro slowly while mix. Better with a long time set and fluid resin. Give a dry paste super light and easy to sand like spackle but stronger. Paint some resin on board before, it help gluing past, with that much micro dry mix isn’t tacky.

Or Sherwin Williams shrink-free spackle has been used to replace the now gray DAP.