3 Easy & water-resistant finishes
Beause of inevitable spills or contact with cold-drink condensation, furniture finishes must provide a good degree of water resistance. As a rule, the more durable the finish, the less fun it is to apply. Steve Mickley, woodmagazine.com's finishing forum moderator and owner of Hardwood Lumber & More in Milford, Ohio (hardwoodlumberandmore.com), says you can give your projects a fighting chance with one of these easy-to-apply, water-resistant finishes. But only if you're willing to break a few finishing rules.
Ignore the directions. Thin your finish.
Oil-based varnish tops the durability charts in terms of water-resistance. The secret lies in its synthetic resins which have been bonded to drying oils and mixed with a thinner. (Faster to cure, varnishes that use urethane for their resin—often labeled polyurethane—dominate the modern market and are easier to find.) When the thinner flashes off and the varnish cures, its molecules form long, hard chains that armor-plate the surface of the wood against moisture.
But applying varnish is not easy. It drips. It bubbles. It broadcasts brush strokes. Aha! That's because you've been following the directions, specifically the directive in bold type on the can that says, "DO NOT THIN."
To meet government regulations for lowered volatile organic compound (VOC) emissions limits, manufacturers reduced the amount of thinners in their oil-based varnish, Steve says. The tradeoff: those pesky drips, bubbles and brush strokes.
Break the rule, says Steve. Stir a can of oil-based varnish. In a separate, sealable container combine one part varnish with one part mineral spirits and stir again. Voila! You've made a wiping varnish. Apply as shown below.
Thinned varnish spreads faster, so it settles flat and defect-free before it dries. It also retains varnish's water resistance, so use this finish on tabletops and kitchen and bathroom cabinets where moisture contact occurs.
Many woodworkers prefer Danish oil due to its ease-of-application (see photo, below). But how do you know it's actually protecting the wood? And what is "Danish" oil anyway? The way the companies obscure the ingredients, you'd think they took lessons from the Central Intelligence Agency.
At risk to his personal safety, Steve reveals the formula: Most Danish oils are simply an oil/varnish blend with some thinner thrown in for ease of application. You can make your own (for a substantial cost savings) by mixing equal parts varnish, mineral spirits, and boiled linseed oil.
You sacrifice some of varnish's water-resistance with this finish on projects that are in danger of only incidental water contact. But you gain a speedier finish and warmer wood tones due to the oil's penetration. As an added bonus, applying a fresh coat repairs dings or scratches.
Ask your finish retailer for a low-maintenance, clear, water-resistant exterior wood finish. Then wait ten minutes for them to stop laughing. You might as well be asking for rainbow-colored unicorn milk. The reason? Exterior finishes take a beating from the one-two punch of ultraviolet (UV) light and exposure to the weather. UV breaks down the finish along with the wood beneath, while temperature and humidity changes swell and shrink the wood, shaking and flaking off the weakened finish. Unless you're paying top dollar for a specialty marine finish, you're left with the yearly task of sanding away the damaged, clear, film-forming finish and reapplying.
Steve's radical suggestion? Use exterior paint. But break the rules—don't tint it.
Wait, isn't that just white paint? Not always, says Steve. Although all paint bases have varying amounts of pigments, providing much of its protection against damaging UV, the base reserved for the darkest colors (usually labeled "deep base" or designated base 4, 5, or E) has the least. A murky tan in the can, it dries virtually clear like a varnish.
But unlike many of the film-forming clear finishes marketed for outdoor use, most exterior paints also contain UV inhibitors to bolster their defense against the sun's damaging rays. Plus, they usually contain mildewcides and fungicides.
Steve used this little rule-bender on an exterior door and it needed only minor touch-ups after seven years of exposure.