I work with epoxy as well, and I learnt that it adds minimal weigth ( with excellent bonding) if I do it this way :

- slightly sand the core for a smooth surface. Do not forget to vacuum the core to remove all foam dust.
- put liquid pore filler on the INSIDE of the balsa skin ( to make sure the wood does not absorb any glue).
- slight sanding to make the surface smooth ( to allow a thinner layer of glue)
- put epoxy on the inside of the sheeting, and squeegee it open. Scrape with the squeegee until the whole surface looks dull ( matt) - as if there is no glue there anymore ( no gloss on the surface anywhere)
- put the skin on the foam, put a cradle under it, and a straight wooden board under that
- put the whole sandwich in the vacuum press

I usually do 1 side at a time - it only takes one hour per side ( with 30' epoxy), so I can get a wing completely sheeted in an afternoon. It is absolutely necessary to use a cradle, and I also put a wooden board under the cradle ( and everything in the vacuum bag) to keep the wing straight.

30' epoxy works great. I just leave everything in the bag for an hour or so and then sheet the other side.

In many cases, i can even work without a separate leading edge : the sheeting can just go around the "nose" of the wing. If working without a separate leading edge, first do the bottom side of the wing, sand the sheeting smoots ( no step anymore) then put the top side sheeting and overlap with the sanded border of the bottom sheeting. If you want, I can take a couple of pics of how a leading edge like that looks like.

If you would work with a glue layer this thin and just weigh it down ( no vacuum), I am practically sure that there would be places where there wil be too little contact between glue and foam for sufficient bonding. Gorilla glue would be the way to go then, as it expands and fills voids, but takes ages if you do only one side at at time, with 24 hrs time for the glue to set.

Kris