[Arran]

Super/Krazy glue is probably fine for stabilizing hairline cracks, but in terms of the open ended ones I've never trusted it. I've heard that it tends to crystallize and come apart in certain circumstances, so for structural repairs I always went with two part epoxy, which is pretty much what J.B is but a higher temp epoxy that is metal filled. It's strange that Bob was having problems with Bondo, the Bondo auto body filler that I am thinking of is a two part polyester resin that you mix together much like you would with epoxy. I've never had any issues with the body filler off gassing, but I have with glazing or spot putty, which comes in a tube and is solvent based.
Regards
Arran