How to Brush on Polyurethane

By Jonah Morrissey

Polyurethane is a clear finish that can be brushed or sprayed onto wood with ease as a top coat finish. It is important to carefully sand the wood surface with a progression of sandpapers until the surface is completely smooth. You should apply at least two coats of polyurethane for a durable finish and sand between coats to ensure a smooth finished surface. Because polyurethane breaks down in sunlight, it should not be used for exterior projects. It is, however, ideal for finishing interior projects with a clear coat.

Sand the surface where you plan to apply polyurethane with a progression of sandpaper starting at 80-grit and finishing at 180-grit for a completely smooth surface. Always sand with the grain of the wood.

Wipe off the surface of the wood with a tack cloth to clean it just prior to applying the polyurethane. It is important to have a dust-free surface for a smooth finish that adheres sufficiently.

Brush on an even coat of polyurethane with a polyurethane brush in long smooth strokes. To remove any air bubbles that develop, lightly back-brush those spots and smooth out the finish. Allow the first coat to dry at least four hours.

Sand the finish with 280-grit sandpaper. Wipe off the surface with a tack cloth. Apply a second coat of polyurethane in the same manner as in Step 3.

Tip

You can apply a third coat if desired for a more durable finish.

Warning

Wear eye protection when sanding. Apply polyurethane in a well-ventilated area.

About the Author

Jonah Morrissey has been writing for print and online publications since 2000. He began his career as a staff reporter/photographer for a weekly newspaper in upstate New York. Morrissey specializes in topics related to home-and-garden projects, green living and small business. He graduated from Saint Michael's College, earning a B.A. in political science with a minor in journalism and mass communications.