Clear Finishing of Outdoor Wood

For many years builders of wooden boats have used a combination of two-part epoxy resins and marine spar varnishes to make "furniture quality" clear-finished watercraft. That these boats look good after several years of outdoor exposure is testament to the synergistic effect of using these products together. The same techniques can be used to protect many wood projects, allowing them to be left outdoors uncovered for months at a time without fear of the finish failing, the wood warping, splitting, or discoloring, and joints coming apart.

Common clear wood finishes are usually separated into two types: film-forming and penetrating. They protect and bring out the beauty of fine woods. Film-forming finishes seal the wood to protect it. Penetrating finishes, usually in the form of stains or water-repellants, allow moisture to move in and out of wood with minimal effect. Outdoor versions of these finishes contain ultraviolet (UV) light inhibitors which enable them to stand up well to the rigors of sunshine. Unfortunately, these finishes are generally poor at excluding both liquid and vapor moisture from cycling in and out of the wood. It is this cycling, combined with degradation from sunlight, which usually causes these finishes to fail. The finish will flake, crack, peel, or simply weather away, and the wood will begin to discolor and split.

System Three Clear Coatâ„¢ epoxy, combined with either System Three Spar Urethane or WR-LPU Marine Topcoat are the perfect finish system for retaining the natural look and beauty of wood outdoors. The epoxy resin sealer will offer protection from everything but sunlight, and it will bring out the natural beauty of the wood. The spar varnish or polyurethane topcoats will block the sun's rays and provide scratch and abrasion resistance. Together, these products will give your outdoor wood projects the ability to withstand the elements and retain their "like new" appearance.

Other items you may need:

  • Rags
  • Sandpaper

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