Over the years interior cedar walls can become dull, dirty and damaged. There is no need to take the cedar down or to replace it. You can strip the finish off of the cedar to reveal bright fresh wood, and then stain or varnish the walls. This will restore and enhance the cedar's color. A coat of polyurethane will protect the wood, making it water resistant and washable. Poly can be used over stain, or over the bare cedar wood to display the natural wood colors.
Use an electric handheld sander to sand the entire wall surface. This removes all of the old stain or varnish, as well as dents, scratches and nicks. If possible, use a sander that collects the dust. Wear a face mask and open all of the windows when sanding. Avoid breathing in the dust.
Use a shop vacuum to suck up all the dust off of the floor, and off of the wall itself. When you are done vacuuming use a soft dry cloth to wipe down the entire wall surface. Particles of dust that are left on the wall will interfere with the outcome of your finish.
Use painter's tape to tape off the ceiling so that stain does not get on it. Tape off any other wall edges or molding that borders the wall. It's better to take the time to tape off surrounding areas than it is to have to refinish them because of a slip or mistake. Cover larger areas using painter's tape and newspaper or plastic.
Use a soft dry cloth to evenly apply the stain or varnish to the wall. For stain, apply and then quickly wipe off all excess. If you want the stain's color to be deeper or richer, apply a second coat and promptly remove the excess with a soft cloth. With stain, there is no wait time between coats.
For varnish, apply an even coat over the entire wall surface. You can use a paintbrush to apply varnish. Apply another coat of varnish once the first coat is dry, wait 1 to 2 hours between coats of varnish.
Fill a tray with polyurethane. Pour it slowly to avoid creating air bubbles. Do not shake or vigorously stir the poly. Apply polyurethane to the main surface area of the wall using a clean paint roller. Roll slowly for the best result. Fill in the edges using an edger or a small paintbrush, soft bristle or foam. Allow the poly to dry 24 hours.
Apply a second coat of polyurethane for the best possible wall result. Your wall will be glossy, protected and easy to clean.