Finish Finesse
Tips from a wood-finishing pro
By: Bob Flexner, author of “Understanding Wood Finishing.”
My son called a while back with a question: How should his girlfriend, who had bought an unfinished coffee table, finish it to show off the natural color of the wood? (Hey, my kids have finally reached the age when they realize I know something!)
I’ve finished furniture for 30 years, but usually with a spray gun. What should I recommend for the girlfriend who has no spray gun and presumably little or no experience? The answer: wiping varnish, the same finish most amateur woodworkers use (without realizing they’re all using the same thing).
Wiping varnish is a name HANDY’s editor, Larry Okrend, and I invented almost 20 years ago to categorize a simple finish sold under many different names. It’s nothing more than regular varnish or polyurethane varnish thinned about half with mineral spirits (paint thinner).
You can easily make your own. Simply buy any brand of gloss — not satin — varnish or polyurethane and pour some into a clean wide-mouth jar or coffee can. Then add about the same amount of mineral spirits and stir. As you become more familiar with this finish, you can adjust the percentages to your liking, usually adding less mineral spirits to give a little thicker build with each coat. The tools needed to apply wiping varnish are in Photo 1.
Thinning varnish or polyurethane by half accomplishes three things:
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It eliminates brush marks. The finish is thin enough so that it levels perfectly.
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It eliminates bubbles drying in the finish. Any bubbles you introduce with brushing have more than enough time to pop out, even on hot days.
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The finish dries faster because it is thinner, so dust nibs are reduced. Though it takes longer for the additional mineral spirits to evaporate, the finish that’s left is very thin so it cures faster.
In addition to great looking results, wiping varnish produces the same excellent protection and durability as regular varnish and polyurethane. You get outstanding water, scratch, heat and solvent resistance — important qualities for all wood surfaces such as tabletops, cabinets and even chairs that receive wear. Wiping varnish is as close to a perfect finish as you get.
How to apply
Of course, you must sand the wood to prepare it for finishing. Sanding is a topic worthy of a separate article or even a book, but it is enough to say here that you sand to remove milling marks using the method shown in Photo 2. When it comes time to apply wiping varnish, use these three methods:
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Brush and leave, just as you would full strength varnish or polyurethane (Photo 3). Because wiping varnish is so much thinner, however, you have to pay special attention when brushing vertical surfaces to avoid runs and sags. Move your head so you can see light reflected on the freshly applied finish. If it begins to sag, lift some off with your brush and deposit it elsewhere or back in the jar or can.
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Brush or wipe and then wipe off most of the excess, leaving just a little (Photo 4).
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Wipe on, and wipe off all the excess.
The first method builds the thickness faster but shows the most flaws, such as runs and dust. The second method is my favorite because it’s the compromise between the first and third. The third produces the most perfect results but requires more coats to achieve any given thickness.
With all methods, allow each coat of finish to dry for 6 hours to overnight in a warm room. To remove dust nibs and any other flaws, sand after each coat except the last, using 320- or 400-grit sandpaper backed by just your hand (Photo 5).
Apply three or four coats — or more if you would like a thicker and more protective build (Photo 6).
To get a thicker build faster — still with almost perfect results — apply several coats using the first method. Then, after sanding out the dust nibs and other flaws, apply a coat or two using the second or third method. Or for an even faster build, brush several coats of full strength (un-thinned) varnish or polyurethane. Then sand out the brush marks and finish with several coats of thinned finish using the second or third method.
To make the finish smoother to the touch, rub the dried last coat with a folded brown paper bag to level dust nibs (Photo 7). As long as the finish is thoroughly dry, the paper won’t scratch it.
To remove the gloss, rub the final coat with #0000 steel wool in the direction of the wood grain, and then rub hard with a soft cotton cloth such as a T-shirt to flatten and disguise most of the scratching caused by the steel wool.
At any point in the future, you can shine up the finish by first sanding to remove scratches and other flaws and then applying another coat or two of wiping varnish.
Commercial brands
Many commercial brands of wiping varnish exist (Photo 8). Only two I know of have names that indicate what they actually are: Minwax Wipe-On Poly and Watco Wipe-On Poly. Both are wiping varnish made with polyurethane.
Other brands have totally uninformative, even misleading, names. Many brands are labeled “Tung Oil,” “Tung Oil Finish,” or “Tung Oil Varnish” even though they have nothing to do with real tung oil. Some are labeled “Waterlox,” “Seal-a-Cell” or “Profin,” which tells you nothing about what’s inside the can.
All of these brands are just as good as homemade wiping varnish, but you have less control of the thinning. Why don’t all manufacturers label their cans in a more user friendly way? I suspect it’s because they want you to think they’re selling you something you can’t make yourself.
