How to Finish Tongue & Groove Walls

Sand your walls with 150-grit sandpaper, working with the grain of the wood. You can use an electric palm sander or a long-handled drywall sander for convenience. Fold up a quarter sheet of sandpaper so you can hand sand the grooves and beads. Remove dust by vacuuming.

Seal the wood with shellac, using an all-purpose synthetic brush sized for your boards. Thin the shellac to half strength with denatured alcohol. Stroke in the direction of the grain of the wood. If you miss a spot or see runs after a few minutes, don't be tempted to retouch them, as you'll end up with a brushy, clumpy texture. Allow it to dry for two hours.

Sand with 220-grit sandpaper to remove bits of debris and even out the finish. Remove dust by vacuuming. This initial coat of shellac serves as sanding sealer, which assures an even finish if you're staining.

Apply stain with a clean, lint-free cloth -- such as an old cotton T-shirt. Let it sit for five minutes, then remove the excess stain with another clean cloth. Work in sections and repeat, if necessary, until you achieve the color you want. Allow it to dry overnight.

Apply half-strength shellac with a brush for the first topcoat. When it's dry, sand with 220-grit sandpaper or very fine steel wool to remove dried bits of dust, then vacuum.

Repeat the shellacking process with a full-strength product until you achieve the depth of color that you want. Don't sand after the last application.