Just another two cents,

The guys that use Pro Bond here had the same trouble with it slopping all over. They used less and less until they were scraping it off with a credit card. They would put the Pro Bond on the cores and the mist the wood.

It has a violent reaction and will lift the skins off if too much is used. In the test pieces that were used it seemed the thinner the better (to a point), and lots of weight while the cores were back in the saddles.

When we cut the test pieces apart, the Pro Bond had forced its way deep into the foam cores and bonded very tightly to the skins without any extra coming out and forming those beads of foam junk.

We then ripped them up to see what would let go first and it was really remarkable that you could not make the skins come off of the cores.

Super 77 seems to work ok, and best if the shrink covering that is used over the wings to finish them is applied the same day.

I have had them come loose but not very often and only on large wings.

The Scimitars that we build use a different approach that I haven't seen anywhere else. They send double sided tape, like carpet tape with the kits.
It holds as well as super 77 and though I have only used it once myself it proved to be a easy clean way to skin the cores. No drying time and no mess.

Like Super 77, I think that to keep the bond you need to use heat shrink covering. The tape works on large models and it might stiffen the wings a little also.

I have never tried to pre form the balsa skins before applying them to the cores, sounds like another no brainer that someone has to point out to me.