Can I suggest that you make a couple of stress risers in your test pieces- put in a couple of glue joints both parrellel and perpindicular to the grain so that you can do some flexure testing to see if it cracks over the joints. I used to paint my quickie 500 racers and tried several things to seal them up- the best thing ended up being mod podge thinned out a little bit with water. It held up great- you should try a couple test pieces with it..