Painting Over Wood That Has Been Polyurethaned

Cleaning

• Before you begin any painting project, thoroughly clean the item to be painted. Use an all-purpose cleaner and a steel wool pad or scouring pad to scrub away the grime and de-gloss the polyurethane finish. Any time you paint wood, you should sand it thoroughly; after sanding, the wood will require another cleaning. Use a vacuum cleaner first to remove the sanding dust, then clean with a damp rag. Finally, rub the wood with denatured alcohol to remove any remaining particles.

Sanding

• The different roughnesses of sandpaper are called "grit." Super-fine sandpaper has a grit of between 360 and 600; very course sandpaper has a grit of 40 to 60. First sand your item with a medium sandpaper, with a grit of 80 to120. Sand in the direction of the wood grain. It isn't necessary to remove all of the polyurethane, but do sand thoroughly to remove any remaining grime and smooth imperfections in the wood. Follow up with a light sanding; use a fine sandpaper with a grit of 150 to 180. Clean the wood again as described in Section 1.

Priming

• A primer is a specially formulated paint that serves several critical purposes. First, it creates a superior surface to which paint will adhere much better than unprimed surfaces. Secondly, primer covers imperfections in the wood that may either bleed through your paint or create tiny imperfections in the paint job. Finally, the primer seals the porous wood so that the paint soaks into the whole piece evenly, requiring fewer coats of paint. If your paint can doesn't specify which type of primer to use, find an all-purpose water-based primer and apply it according to the manufacturer's directions.

Painting

• Paint your wood with either oil-based or acrylic paint. Acrylic paint dries faster and cleans up better than oil-based paint, but it is not as durable. Use a good-quality brush. Let the paint dry thoroughly to the touch, then apply a second coat. If you plan to finish your paint job with a coat of polyurethane, do so after the paint has been dry for 24 hours. Always apply at least two coats of polyurethane. Between coats, sand thoroughly using an extra-fine sandpaper with a grit of 280 to 320, then clean with a vacuum cleaner followed by a damp cloth. Do not use solvents between polyurethane coats.