I am varnishing (with polyurethane) a table top. I have done many like this before but never encountered this problem. I applied two thin coats of clear gloss poly to the wood (nicer grade Birch plywood) before applying a colored varnish coat. The first color coat showed these signs of no adhesion or "crawling" in a few spots. Couple thoughts...
1. I did not clean or neutralize the tops prior to applying the poly....oils, dirt? Perhaps applying a wax free shellac to seal
2. Could I sand it down with 400 a bit, apply some shellac then re-try the poly?
Thx for any advice....2 other tops from the same stock did not have this issue and both were prepared the same way.