That's a great idea to also try, Terry.

A. Edie makes an important different point - all surfaces should be washed to remove possible oily residue. This is another bitter lesson to learn, heh heh.

I can't speak for Jake, but in my case the causation came from 'frothing' the resin/glass by repeated brush stippling/pounding to get the cloth to lay down in awkward areas (odd shaped and successive laps). The 'frothing' then became permanent when setting up. During sanding the microscopic holes filled with the 'white' epoxy sanding dust that would not wet out, would not spraywash out (I also tried a tooth 'pik' dental washer that directed high pressure in tiny jets - to no avail) and in most cases - espec the small ones - could not be brushed out. As the original surface was stained, the boat would have been destroyed (didn't want to paint) if no remedy could be found.