On 2006-06-24 03:26:42 -0400, ray lunder said:

And don't forget to put a sheet of plastic between the core and resin
if you're working next to the core. (the foam reacts with the epoxy
and gasses, leaving voids).

This is rather bad advice. In almost all cases, you WANT THE RESIN AND
PATCH TO BOND TO THE CORE. Putting plastic between the core and the
resin leaves a void too, just not one filled with gasses. Most cores
DO NOT react to Epoxy by dissolving and gassing off... especially if
the core is a good end-grain balsa, which it is on the better boats. If
the core is not bonded to the repaired area, you have effectively
created a section that is pre-delaminated. DUH.