I built a bookcase out of red oak. I used a Minwax stain after sanding. The stain dried for about 12 hours before I put Minwax fast drying polyurathane on it. About an hour later, I checked the finish and it was completely dry. I applied it in the shade so I decided to put it in the sun to allow the polyurathane to harden. 15 minutes later, I checked it and there were small bubbles all over the bookcase. What caused that?
-- Jeff, McDonough, GA