I think you're talking about resin exotherm melting the foam.
"Burn through" is a term we use when oversanding the hotcoat into
the glass.In summertime heat (80 degrees ) the epoxy resin will tend to
exotherm in deep holes as in FCS X-2 plug holes and ding repairs. FCS fusion,
FCS II, and Futures are a tight fit and use very little resin so no worries
there.We recommend pouring only
about a 1/2 ounce of epoxy into a hole at a time then waiting about an hour
to fill up the rest of the hole. This will stop the epoxy from exotherming
and melting EPS.