Penetrating oil finishes are popular because they’re easy to use. They provide a close-to-the-wood effect, soaking into the surface instead of lay-Mg on top, as film finishes do. Oil finishes are actually oil-varnish blends, often called Danish oils. Don’t confuse them with natural oils, like boiled linseed oil or pure tung oil, or with nondrying oils, such as min-eral or vegetable oil. When oil finishes cure, they seal pores and protect wood from dust, dirt and wear. Application is simple: Soak the wood with a brush or rag, wipe off any excess and let dry eight hours before you recoat. Sand lightly between coats, applying three to fours coats, and you’re done.
- Oil finishes, which are technically a blend of oil and varnish thinned with mineral spirits, are extremely easy to apply. They impart a more natural look with a satin sheen, but offer only moderate protection from scratches, water and stains. Caution: Oil-soaked rags can ignite spontaneously because of heat buildup. Place used rags in a fireproof container or spread them outdoors to dry thoroughly before you dispose of them.
- Oil finishes can be wiped on and wiped off
- The finish can bleed back out of the pores without worrying about dust. while the surface is wet, requiring vigilant
- You feel and see the wood instead of rewiping. the finish.
- The super-thin mixture builds up less than
- You can renew a worn-out finish by simply varnishes and film finishes do, offering sanding lightly and recoating. minimal protection in hard wear or high moisture areas.
Flood surface using a rag or brush, let stand for five minutes and wipe excess before the finish becomes tacky. Continue wiping any oil that bleeds back to the surface. To smooth the surface while you apply an oil finish, wet-sand after the first sealer coat. Smooth the dried finish by rubbing with paste wax or rubbing compound.
Natural oils, like tung and linseed, make wood look rich and beautiful, but because they soak into the wood, instead of sitting on the surface, they don’t offer much protection. Oil/varnish blends are easy to apply, look good and offer more protection than natural oil, but less than straight varnish.
Varnish, a film-type fin-ish, offers excellent protec-tion and adds a warm glow to woods. Two types exist: straight varnishes, which offer superior protection and are made from a blend of resin, oil and solvents, and wiping varnishes, which are simply thinner versions that can be wiped on instead of applied with a brush. Wiping varnishes require three to four coats and are similar to oil fin-ishes, except you wipe on thin coats and leave each coat alone without wiping away excess. Regular varnishes are brushed on the same way as polyurethane (see p. 455), which itself is a form of varnish. Their thicker consistency allows you to achieve the same effect in only a couple coats.
- Wiping varnishes (left side) are thinned-down versions that let you wipe instead of brush them on, but you’ll need to apply more coats to achieve the same finish thickness. Regular varnishes (right side) build quickly with a few coats and protect wood while adding a glassy look.
- Varnishes, including wiping varnish when its applied in multiple coats, offer good moisture and wear protection. • Spar varnishes can be used outside on doors and patio furniture to protect against the elements.
- Varnish takes six to 24 hours to dry, so keep work areas clean to avoid dust contamination. • Air bubbles can spoil a varnish finish if you don’t use a good brush and proper brushing technique.
Working Tips: Use lint-free cloths washed cotton works great for applying wiping varnishes. Fold the cloth into a ball, dampen it with finish and wipe on light coats, overlapping each stroke with the grain of the wood. Don’t go back over the finish or you’ll leave marks. Thin the first coat of regular varnish 25 percent to 50 percent with mineral
spirits. Apply subsequent coats full-strength. Use a natural-bristle brush with flagged ends and a chisel shape. Allow coats to cure, six to 24 hours, depending on type and brand before smoothing with fine sandpaper. Rubbing with paste wax or rubbing compound will help smooth the final surface.