How to Apply a Polyurethane Coating to a Bar Top

Prepare the surface of your bar. Sand the bar top lightly to remove any dirt, oil or other contaminates and to roughen the surface for better adherence of the polyurethane. Wipe the bar with a damp towel, rinsing often, until it's free of dust. Allow it to dry completely.

Thin the polyurethane. In a separate container, mix approximately 10 parts polyurethane to approximately 2 parts paint thinner. It's not necessary to measure the parts precisely; you can dilute polyurethane up to 50 percent. Stir well with a wooden stir stick.

Apply the first coat of polyurethane. Dip your foam brush in the polyurethane mixture and brush it on the bar top in square-foot sections. Use back and forth motions in the direction of the wood grain. Brush each section repeatedly until most air bubbles and brush strokes have disappeared. Move to the next section and repeat the process, overlapping the previous section by an inch or two.

Allow the polyurethane to dry completely. This may take up to 12 hours, depending on the temperature and humidity of your work area. Check for dryness by lightly touching the surface. The surface should not be sticky, and touching it should not leave fingerprints.

Sand the first coat. Sand lightly in the direction of the wood grain to remove any bubbles, brush strokes or specks of dust.

Clean the surface thoroughly. Use a clean, damp cloth to remove the residue from sanding. Rinse the cloth often and wipe until all dust has been removed.

Repeat Steps 3 through 6 until you have applied three coats of polyurethane. Use a new foam brush for each coat.

Apply the last coat using full-strength, undiluted polyurethane. Brush thoroughly to minimize bubbles and brush strokes. Don't sand the last coat. Allow it to dry for at least 24 hours before placing anything on the surface.