by Chris Black
The furniture studio where I fill in on occasion uses an industrial post catalyzed lacquer finish on most of their commissions. Although it dries in 8 minutes and is pretty much bulletproof, applying this type of finish requires some expensive equipment. In my own shop, I prefer to use off-the-shelf finishes that don't require donning a chemical protective suit or building an elaborate spray booth. I feel like I can still produce good looking finishes for my clients without sacrificing durability or requiring too much drying time. If it takes 24 hours for a finish to dry, you probably aren't making any money on the job. The key is to pick an appropriate finish for the project. Knowing how the piece will be used, where it will live and who will be using/abusing it will help you pick the right finish.
Shellac is unquestionably my favorite finish. Shellac dries fast, looks great, touches up easily, and is relatively safe to use. When mixed fresh from shellac flakes and used within a couple of weeks, it's quite durable. Aside from being a world-class topcoat, dewaxed shellac is also a universal sealer. Put it over a water-soluble dye before top coating with a waterbased finish to prevent the color from bleeding through. You can also add Transtint concentrated dye drops in shellac for shading and toning. I apply shellac to any interior project that doesn't get super heavy traffic or a ton of moisture. For instance, shellac would be perfectly appropriate for a dresser, side table or gift box, but it wouldn't hold up well on a bar top or on an employee break table. I usually apply shellac with a homemade pad/rubber/mouse or spray it on.
Waterbased finishes generally come in two varieties; acrylic and polyurethane. The polyurethane variety is slightly tougher and can be used on floors and tabletops. Today's tough waterbased finishes dry fast, clean up easily, and you don't need a fireproof spray booth. They also cure fast, so you might only have to wait a couple of days if you want to rub out the finish to a high gloss. As a result, almost all commercial jobs that come out of my shop are coated with waterbased topcoats. I also finish all bathroom fixtures, kitchen cabinets, entertainment centers and most bookcases with waterbased films. By adding a few drops of amber colored Transtint dye in the finish, I can make the final coat look remarkably like an oil based film without the slow drying time of oil. While I like to spray waterbased finishes, most can be brushed on. Our Ceramithane brand seems to brush on the best. Use a good synthetic brush like our Purdy Nylox/Polyester.
What about good old oil? Well sometimes a job gets spec'd for oil or you have a piece made from walnut or cherry that's just screaming for a little oil. The key to using an oil based finish is not to use oil. That's right. Natural oils like tung oil, linseed oil and oil varnish blends take too long to dry and don't offer much protection. Plus they're expensive and you wind up paying mostly for paint thinner. My solution is to buy a true short oil varnish like Behlen's Rock Hard Table Top Varnish, and cut it back with equal parts paint thinner so it can be wiped on. These over-the-counter varnishes are much more durable than the true oils, and they are loaded with dryers. On a nice day you can apply three coats of thinned varnish and no one will be the wiser. Try this experiment. Take your favorite oil or oil blend and wipe it next to a coat of thinned varnish. Wait a day and see if you can tell the difference other than one of them will still be tacky.
I like to apply this type of oil finish will a clean, lint-free cloth. After I get the surface covered with the finish, I go back and level the varnish with a rag trying to remove as little material as possible. Keeping more finish on the wood will reduce the number of coats you have to apply. Don't overwork the wet finish. Varnish, if left alone, will self-level to flawless perfection.
Occasionally I'll get a job like a bar top that's spec'd out for an epoxy finish. You know, it's the type of finish that looks like 50 coats of polyurethane. It's best to use a very viscous epoxy product designed for this sort of thing like our Envirotex Lite. Make sure you follow the manufacturer's instructions to the letter or you're liable to wind up with an uncured, bubbly mess. Also, epoxy finishes don't hold up well in sunlight. If the piece will be outside, it's best to coat the dried epoxy with several coats of a good spar varnish.
Spar varnish is of course the choice for clear coating exterior jobs. Recently some two-part super-performing products have entered the professional boatbuilding market, but I won't go into them here. When choosing a spar varnish, make sure it is a true long oil varnish loaded with a UV light-protecting mineral. Here are some hints. If you can find it at a blue or orange colored home center and it costs under $90 a gallon, it's no good. Decent spar varnishes are typically made from tung oil and have a very slow curing rate, so they remain relatively flexible to accommodate the seasonal movement of wood. Also they contain minerals that act in a similar way as paint pigment which helps keep the sun from breaking it down so quickly. The thing to remember about spar varnish is that more is better. The more film between the world and the wood means better protection. So, load it up! Apply all varnishes with a high quality natural bristle brush. Cheap brushes will shed hairs in the finish. For more information on exterior finishing, check out our Q & A in the October 2007 issue of Wood News Online.