How to Prepare Very Dirty Plywood Paneling for Painting

Briskly rub the sandpaper over the soiled wood to lift and remove surface dirt and dust particles, concentrating on stubborn, very dirty areas. Wipe sawdust away from the wood with a dry cloth.

Apply one thin coat of clear or amber shellac to the paneling and allow it to dry completely. Apply a second coat of shellac. The shellac will seal the wood, preventing any more dirt or dust from getting trapped inside the wood grain, pores or cracks and will help you achieve a smooth painting surface. It will also prevent the wood from splitting or cracking over time and will help protect your wood from moisture or water damage.

Apply one coat of gray or white paint primer to the wood paneling and allow it to dry completely. The primer will help to conceal dark dirt stains and prevent them from showing through your paint. In addition, the primer will help create a smooth surface over any remaining dirt, preventing small bumps from showing through your paint job.

Paint two coats of paint on the plywood paneling once the primer is fully dried, allowing adequate drying time between coat applications.