Rob: Epoxy is the way to go on both. When fuel proofing the engine and tank compartment with epoxy heat it so it will flow and get in all the cracks etc. and is easier to spread.

My reference to "heating" the epoxy was only for spreading it around the tank/engine compartment.   I do not heat the epoxy when I am actually gluing any parts together.  I like for the epoxy to take it's time curing in that situation  so that a maximum bond is achieved! 

Bill <><

Hi Bill

  Right you are  , Nothing wrong with  heating epoxy, I routinely do it, but that is why I recomend  slow cure, still gives time to soak in and good working time, if you heat  fast cure, it can get thick before you can even get it in place. Plus  if you heat the slow cure as  you know  , it is much easier  to spead around for fuel proofing, and  also it help the glue to soak in better when you want a good joint.
Great for  pipe tunnels , you can fuel proof the tunnel  with just a little  glue , although when I do fuel proofing i normally paint dope over the wood first to stop the raw balsa  from soaking up epoxy. That way you don't have much weight gain
Another  use  for  heated epoxy is when you  are sheeting foam components, the slow  hot epoxy is much easier to spead around and  scape off, so you get a better bond with less  glue


Regards

Randy