Spring is in the air and it’s time to start getting out the outdoor furniture and decorations. If they’re made of wood, you’ll want to be sure they’re protected from the elements before you put them out for the summer. Wood left bare will gray from the sun, begin cracking and change shape; twisting, cupping or warping as moisture moves in and out of the wood. Some woods handle the elements better than others but ultimately they will all succumb.
Sunlight and moisture are really hard on wood and all outdoor finishes require maintenance to keep them protecting your wood. Moisture can cause wood to rot or distort and ultraviolet (UV) light bleaches out the natural wood color.
Here are some outdoor finish options you can choose:
Absolutely Nothing. This is clearly your easiest option and some woods, like teak, cypress or cedar are rot resistant and are capable of aging gracefully without protection. The wood will gray quickly and probably won’t last as long as if you had applied a finish. It helps to sand the wood to a smooth, polished finish to seal the pores and reduce moisture penetration.
Exterior Oil. Easy to apply, great to touch, and beautiful to look at. Rather than creating a film on the wood, oil soaks into the wood fibers and dries. Exterior oils have UV and mildew protection added. Unfortunately, oils don’t provide much protection from marring and will need recoating every year.
Exterior Varnish or Urethane. These finishes build a protective film layer over the wood that is much more durable than oil finishes. You may have heard the term ‘Spar’ varnish. It refers to the finish used on the spars of sailing ships back in the day but it really doesn’t indicate any special added ingredients. All exterior varnishes and urethanes are formulated with UV and moisture protection and should be applied in multiple, thin coats. Clear finishes are vulnerable to direct sunlight and will need to be recoated as soon as they start to fade.
Epoxy Finish. When applied over exterior varnish, epoxy is the most durable and the most labor intensive exterior finish. It’s the finish preferred by boat builders because it forms an impenetrable moisture barrier and the varnish layer beneath provides the UV protection. It creates a great, long lasting seal but it takes a lot more work to apply.
Paint. Want the best, longest lasting finish? Exterior grade paint over oil based primer gives you the best UV resistance and moisture barrier. Of course, it means covering up the wood grain and hiding the natural color. The payback is that done right, a painted surface can hold up for ten years
Here are some finishes you should avoid for outdoor applications: wax, shellac, lacquer and interior finishes. They all serve well indoors but will break down quickly if you take them outside.
Outdoor finishes require maintenance. You just need to decide on the right trade-off between application ease and service life.
