Sometimes I get ahead of myself during glue-up and have to pull a joint apart. I’ve found that lacquer thinner will dissolve ordinary PVA wood glue if you apply it before the glue dries hard. Just brush a liberal coat of thinner into the joint, and wait a few minutes for the glue to turn rubbery. Then you can often wriggle the pieces apart without damaging them. This works best on exposed joints like rabbets, and it can save the day!
– Don Vercamen