How to Apply Varnish to Unfinished Wood
Applying varnish directly to unfinished wood produces a durable, clear finish through which you can see and enjoy the natural beauty of your wood and its grain patterns. In fact, stains and other colored finishes serve mostly a decorative purpose unless they contain a varnish component such as polyurethane. Two or three coats of varnish protect unfinished wood against everything from spilled coffee on a tabletop to heat, precipitation and wind on outdoor trim. You do need to prepare the wood by cleaning and sanding it before you actually apply varnish.
Step 1
Replace any sections or panels that have black knots or knots with cracks in them. Sand the entire wood surface to be varnished with fine sandpaper or a sanding block. Use an electric palm sander if you have one available. Sand in the same direction as the grain on the wood.
Step 2
Wipe the sanded surface with a soft, dry cloth and then wipe it again with a tack cloth to remove all sanding dust.
Step 3
Apply an even coat of oil-based or water-based polyurethane or spar varnish to the sanded wood with a natural-bristle brush. Allow the varnish to dry for at least 12 hours. Clean your brush with mineral spirits for oil-based finishes or a soap and water solution for water-based varnish.
Step 4
Lightly hand-sand the varnished surface. Wipe it with a tack cloth. Apply a second coat of varnish with a natural-bristle brush. Clean your brush as soon as you are finished. Allow the surface to dry for 12 to 24 hours before sanding again and applying a third coat if desired or before using your varnished furniture.
