RE: West Systems epoxy
West Systems epoxy if by far the best for structural laminations and for carbon graphite or kevlar. For finishing balsa to paint I would use Polyester resin and .5 to .75 oz glass cloth. It is plenty strong, light weight, and easy to apply. Use only enough resin to leave a weave pattern behind, do not fill the cloth all the way. Sand lightly and prime to fill the top of the weave. Some people have good results by painting on the resin, laying on the cloth, and blotting excess resin off with a hand wrapped in many layers oftoilet paper. Don't laugh, it works great.
Good luck
Scott