I built a set of corn hole boards put 3 coats of gloss black paint on them can I use this to give them the extra shine a slick surface

Hello, Generally, we do not like recommending top-coating paint. Paint is typically a very durable coating that will not benefit from the addition of a clear finish. However, if you wish to proceed with this type of application, the only products we offer that will be suitable over paint would be the Polycrylic or the Water-Based Helmsman Spar Urethane. Neither of these coatings will amber over time, which is typical with other polyurethane type products. To apply this product, however, you will need to allow the paint to fully cure (at least 30 days) first. This will prevent the solvents in our products from reacting with those still remaining in a still-curing paint coating, avoiding the color running, discoloring or hazing. Once the paint has cured, scuff sand the surface using a 220 grit sandpaper (removing the dust with a damp cloth) and then apply your clear finish per label directions. You should have pleasing results for your project. Regards, Minwax Customer Support

I believe that if you put 3 coats of black gloss enamel paint that you would not gain any more luster by using this as a top coat.