Varnish is a tough, durable, easy-to-apply finish that lasts for years. It has been used for centuries as a protective coating for everything from ships to fine works of art and musical instruments. It works equally well either applied directly to a wood surface or as a top coat over other, compatible finishes. The most common home-owner application for varnish is as a protective coating for outdoor furniture, toys and play sets. Lowe's is happy to provide this information as a service to you.
Tools & Materials
- • Rubber gloves
- • Protective eyewear
- • Dust mask
- • Tack cloth
- • Paintbrush or clean, soft cloths/rags
- • Sandpaper
- • Fine steel wool or synthetic steel wool
- • Varnish
- • Paste wax or furniture polish
Characteristics of Varnish
As the varnish cures, its molecules react with oxygen to form a strong chemical bond. After curing, varnish forms a protective film that is highly resistant to:
- • Solvents
- • Acids
- • Water and water vapour
- • Scratches and wear
- • Heat
This protective film is what makes varnish such a desirable finish for any surface that is used hard or exposed to the elements. It flows well and has a relatively long curing time so it has time to self level. The long curing time does make spraying varnish rather difficult. The over spray tends to stick to any surface it touches. But, with its above-average leveling qualities you can easily achieve a high-quality finish by either brushing or wiping. There are basically two categories of varnish:
- • Interior varnish cures very hard and can be buffed to a shine rivaling lacquer.
- • Exterior varnish cures slightly softer than interior varnish and remains resilient enough to expand and contract with outdoor materials.
This boat door looked like it had seen its better days. After some meticulous sanding and a few coats of exterior, gloss varnish it looks as good as new.
The three most important factors in a successful finishing project are:
- • Preparation - The surface must be clean, dry and smooth.
- • The finishing material - You should have the appropriate material for your particular project. Use interior varnish for indoor projects that require a very hard film. Use exterior varnish for projects that will be subjected to extremes in temperature and regular expansion and contraction of the material being finished.
- • The applicator - Use the appropriate method of applying your finish and always use quality brushes, rollers, rags or sprayers, matched to the type of finish you are using.
If some sanding and a little varnish can revitalize this neglected, old boat trim, just imagine what it can do for your exterior trim.
Preparation and Application
Finishing highlights the beauty of wood, but the process also magnifies imperfections. Sand the wood smooth and repair all defects before finishing.
- 1. To produce smooth surfaces on bare wood, always sand with the grain of the wood. The material should go through at least three sandings with successively finer grit sandpaper. Start with 80 grit, move to 150 grit and finish with 220 grit. Use a tack cloth to remove dust between sandings.If you are using varnish as a topcoat over another finish, simply scuff sand the existing finish with steel wool or synthetic steel wool. Scuff sanding gives the varnish top coat something to bite into for better adhesion with the existing finish.
- 2. On bare wood, apply a light coat of varnish and allow it to dry fully. After the first coat has dried, lightly sand, with fine grit paper, to remove any raised grain. On an existing finish, apply a coat of varnish and allow it to dry according to the manufacturer's instructions before.
- 3. Sand the dried varnish lightly with 400 or higher grit sandpaper, steel wool or synthetic steel wool. Remove any sanding dust with a tack cloth.
- 4. Brush or wipe on another coat of varnish and allow it to dry.
- 5. Continue to apply coats of varnish as indicated in steps 2 through 4 until you achieve the surface build-up you desire.
- 6. Inspect the finish for small nicks or imperfections. Rub out any rough spots with steel wool or synthetic steel wool. Wipe with a clean tack cloth to remove any dust. For extra protection, polish the surface with paste wax or furniture polish.
- • Always apply finishing materials in a well-ventilated area.
- • Wear eye protection and rubber gloves to prevent exposure to finishing materials.
- • Read and follow the manufacturer's instructions and cautions.