I resurfaced a bar with maple luan. After staining the surface I cleaned with tack cloth and applied spar varnish. The first coat had a lot of little "bumps" so I sanded and applied a second coat. Still lots of little bumps. Third coat and same result. How can I get rid of the bumps in the finish? At this pace it will have 10 coats of spar varnish. Any help out there?