DesertDude,
I do the same as you describe except that I use Helmsman Spar Urethane in the tube. I usually apply 5 or six thin coats that way and allow to dry for a full day. I have done this with maple, ash and a few POC. Duco for the fletching.
Just pulled one out of the grass that had been under there for 7 weeks (yeah-I missed with a new bow), ash with very open grain, and it was ever so slightly bowed away from straight. Maple and cedar would have stayed straight in my experience (not that I miss that much....).