How to Finish a Tabletop With a Polyurethane Finish

Relocate the table outdoors or into a garage where you can get more ventilation if possible. If not, open all windows and doors in the room where you plan to work and aim fans outward from the room in doorways or windows for ventilation.

Sand the tabletop if the surface feels rough to the touch. Use fine-grit sandpaper on a sanding block and move across the surface in a circular motion until the surface feels equally smooth to the touch all the way across. Wipe the tabletop with a tack cloth to get rid of the sanding dust.

Apply either paint or stain with a paintbrush in long, even strokes. After the stain sits for approximately five minutes, wipe any stain left on the tabletop away with a dry rag. Wait until the paint or stain dries fully, and apply a second coat if necessary to reach the color you want to achieve.

Apply the polyurethane finish over the top of the paint or stain once the paint or stain feels completely dry to the touch. Brush the finish onto the tabletop with a standard paintbrush just as you did the paint or stain, applying the finish as evenly as you can. Once you are finished with the application, let the polyurethane dry on the surface for 48 hours.

Look for any bubbles in the polyurethane finish, which may occur if too much air got into the finish. If you find bubbles and you don't like the way they look, sand the areas with bubbles down with fine-grit sandpaper until the bubbles no longer show in the polyurethane. Wipe up the dust with a tack clock, and then go over the area where the bubbles appeared in the finish with more polyurethane and allow the polyurethane to dry. Repeat until the bubbles have completely disappeared.