Light wood finish: varnish vs. oil

There are many clear wood finishes on the market today. Two of the most popular are polyurethane varnish and tung oil stain. tung oil stain.. While polyurethane is a synthetic material, tung oil stain is organic and is made from the pressed seed extract of the tung tree. This article compares the two in terms of pros and cons, application and equipment, and maintenance and cleaning of your solid wood furniture. solid wood furniture.

Polyurethane varnish

As a liquid plastic, polyurethane goes on, as opposed to wood. It requires some skill to apply, but can be used by novices if they do their homework. The end result is a durable, high gloss, protective coating. This finish can be applied to raw wood as well as to freshly stained wood or over old varnish if the wood is sanded thoroughly. Polyurethane is best for most exterior wood surfaces subject to moisture, fungus or mildew and is a must use for any marine environment. It may require recoating as often as every year depending on items such as boats, but in protected areas or indoors, the surface can last for years without reapplication. When used on furniture and cabinets, it can be maintained with a typical wax powder spray.

The major drawback of varnish is that it will eventually crack or peel, and water and mildew can discolor the wood underneath.

Tung oil stain

But your house isn't a boat, is it? Tung oil is used primarily on furniture, cabinets, interior doors and trim, and is very easy to apply, coat and maintain. It penetrates the wood, so the finish will never crack or peel, unlike polyurethane. It has less gloss than varnish, but has a more velvety feel and visible grain. For maintenance, simply wipe with a dry cloth, but never use a spray wax because that will prevent it from being reapplied. A final great advantage is that it can be reapplied without sanding.

Polyurethane application

Applying polyurethane requires a fine bristle brush designed for oil-based paints, paint thinner, a small bucket with a handle, lint-free rags such as old cotton t-shirts, a wire bristle brush, 220 grit sandpaper and a lot of patience. In a sense, varnish is like nitroglycerin in that it does funny things when agitated, such as creating lots of air bubbles. To avoid bubbling, use a pressurized plastic pour tube for a gallon can. Transfer less than needed to the cut bucket, as pouring the excess back into the gallon bucket causes more of those annoying bubbles. Focus the pour against the side rather than directly on the bottom.

Then, wet the brush minimally, brushing the excess onto the edge of the bucket. Using a dryer brush will help avoid drips and puddles. Hold it at a different angle with the handle closer to the wood and apply with long, even strokes. The first coat should be the thinnest of all, so don't overdo it.

Use all the varnish on the brush and lightly remove any drips, puddles or bubbles. Small bubbles may disappear during drying, but can be sanded out before the next coat. Wait 24 hours between coats and remove excess dust with a rag dampened with paint thinner before each new coat. Use a minimum of two thin coats rather than a single thick coat, as thin coats are essential to avoid cracking caused by exposure to sunlight and the elements. The final dry coat can be smoothed with extra fine steel wool, number 0000, or synthetic steel wool to avoid any metal "filings" left on the surface, but stay away from sharp corners, concentrating only on flat areas. Again, lots of patience and slow, light but long strokes are the keys to an attractive finish.

Application of tung oil

This is where tung oil shows its advantage. You will need a high gloss tung oil, dyed sponges (a small sponge covered with a towel), clean cotton rags and a cut bucket. Depending on your surface, a blunt screwdriver covered with a rag is also useful to remove excess oil from tight corners.

Quicklyweta large portion of the wood, as much as possible in four to five minutes. Do not allow the tung oil to dry more than five minutes before wiping off the excess oil with a rag and then again with a second dry rag, buffing hard until the surface becomes slick. This hand rubbing is more important on the final coat than the first coat. Apply a minimum of three coats, allowing 24 hours between coats. Almost no sanding is required if you have polished well. Subsequent coats can be applied at any time to renew the gloss after a light wipe with a rag dampened with paint thinner.

Just before topcoating, for a silky, super smooth finish, very lightlysand the flat areas with 440 grit wet or dry sandpaper from an auto parts store. Wet the paper with a minimal amount of oil before sanding.

Here you can see how to apply an oil on the wood surface.

Clean

To clean the varnish brush, dip the entire brush in paint or lacquer thinner in a clean bucket, working the brush against the bottom of the bucket. Work the thinner through the bristles with your fingers and a wire brush, concentrating on the base of the bristles. Repeat until the varnish is gone before making a final cleanup with fresh thinner. Brush the thinner onto a clean board or absorbent piece of cardboard. Finish by tapping the brush back and forth over a corner of a clean board, and work a dry rag through the bristles one last time. To clean the bucket, wipe itwith a rag and thinner, and give it a final wash with detergent and warm water.

For oil cleanup, packoily rags and sponges in plastic and throw them in the trash. Clean if necessary with thinner, ammonia-based window cleaner cuts the smell of solvent, dish soap and water. Clean the dry cutting bucket.

And that's why using oil is so much easier. No skills, less equipment, little cleanup and no "hard brush in the morning" worries.However, no matter what finish you decide to use, good luck and remember that patience and hard brushing pays off.