Applying a clear wood finish
Use a tough polyurethane varnish on tables, floors, and other surfaces subject to wear and spills. On other jobs, a less durable alkyd-based varnish can save money. For a clear, nonamber tone, use an acrylic varnish; spray it like lacquer. Reserve a weather-resistant, phenolic-based spar varnish for outdoor trim.
Most varnishes come in gloss, semigloss, and satin (dull) finishes. Sand the surface to be varnished, ending with fine (220) paper. Any previous varnish must be well abraded. To control dust, vacuum the surface and surrounding area. Then use a tack cloth to remove fine particles. Seal stained wood; avoid shellac sealer if the varnish’s label so indicates.
Applying the varnish
Work with good ventilation away from open flames. Use a clean, chisel-cut, natural-bristle brush. Apply varnish full strength; for raw wood, thin the first coat as directed. Avoid making bubbles in the varnish. Don’t shake the can. If necessary, stir it gently. Pour the amount you’ll need into a wide-mouth container. Dip the brush bristles a third of the way in. Remove excess by gently tapping the brush on the container; scraping it causes bubbles to fall into the varnish.
Flow the varnish on in long, even strokes with the grain; go a surface’s full length if possible. End a stroke by gradually lifting the brush to avoid leaving a ridge. Barely overlap the next stroke. Then wipe the brush dry on paper towels and brush vigorously across the grain to pick up excess varnish. End by lightly drawing the brush’s tip along the grain.
Unless it has worn, older varnish needs only one fresh coat. A new surface needs two; a heavily used surface, three. Between coats, let the varnish dry 24 hours and sand with fine (220) paper; follow the label directions for polyurethane. For a hand-rubbed finish, sand the last coat. Then sprinkle on powdered rottenstone with a little mineral oil. Rub with 0000 steel wool.