Choosing a Varnish for Your Brightwork
Marine varnishes have been applied to protect and preserve woods on boats for many, many years. History indicates that varnishes applied in the 1700s are very analogous to what is used nowadays. The applications allow for the rich beauty of the wood to be viewed while providing shelter from the elements. The finish achieved after slow application will deviate from a soft patina to a high gloss finish akin to fine furniture.
Presuming you wish to protect and beautify your boat’s exterior brightwork, how do you choose among the incredible variety of finishes? Recognizing completely that this is as big a deal as arguing the differences of single engines vs twins, we nevertheless offer the following observations.
What is a Varnish
A varnish is a liquid coating ordinarily used to treat teak. Its primary ingredients are oils. resins, solvents, dryers and possibly ultra-violet additives. The components are mixed in various proportions to give the best visual aspect and protection.
Oils
Wood oils generally hold the original look and texture of the wood to a greater extent than the other finishes because they penetrate deep into the wood fibers and do not create as much of a surface finish. Wood oils are available in colors ranging from water clear to gold to dark brown. As with all wood finish, many coats generally lead in a much more consistent finish and greater longevity. We find oil to be the simplest to utilize, since surface blemishes are not as obvious in the final outcome. This doesn't mean, not withstanding, that slapping several coats of wood oil on raw teak will produce a Bristol finish. You will also find that oil’s thin consistency makes masking areas to protect surrounding gel coat and painted areas almost as crucial with oil as with varnish. Clean, sanded teak with 3 or 4 coats of oil will give your teak 3-6 months of protection and beauty.
Tung oil is used frequently for teak applications.
Spar Varnish
Spar or marine varnish is a refined product consisting of oil, solvents and thinners, resins, dryers and additives. By changing the proportions of the components and by adding ultra-violet inhibitors and other protected components, manufacturers create varnishes with widely varied characteristics. Varnishes can have a high gloss or matte appearance, can be formulated to be super hard for high-use surfaces and can vary in color.
The two most routine varieties of varnishes are natural resin varnishes such as tung oil and oil-modified polyurethane varnishes. Natural tung oil varnishes are great for marine use and provide the classic golden look. Polyurethanes tend to be more clear, permitting the color of the teak to shine through.
Newer varnishes, furnish improved durability in the harshest of environments such as the hot, tropical sunlight. Wood moves, since it is a previously living plant, it expands and contracts with even small changes in temperature and humidity. Premium varnishes cope with this unstable material using high quality oils and resins and a greater percentage of solid components, providing a longer lasting, more flexible coating with a greater gloss.
Thickness is everything. Six to ten coats is usually required to get a quality look. A sound base coat, yearly maintained with a single maintenance coat, will give the ultimate in appearance, longevity and protection. Despite the initial effort (up to 10 coats are common) nothing looks better than exterior teak finished with gloss varnish.
Interlux’s Original 90 is just one variety of many traditional spar varnishes on the market.
Synthetic Wood Finishes
These coatings gained popularity with cruisers in Florida and the Bahamas looking for UV-resistant low-maintenance brightwork. Developed for ease and speed, these finishes have uncommon durability for outside use, are simple to apply and look comparatively good. I say comparatively good as some of these finishes, like Cetol, have a colored appearance, sometimes with an orange tone. You must be careful not to apply too much. Some spar varnishes such as Interlux Goldspar and Schooner are produced with no pigment so the wood’s natural appearance is retained. Full gloss and depth vs. convenience is the trade-off with these finishes, but ease-of-use and labor savings can more than compensate. Applying synthetic finishes is similar to teak oil, where you can apply it directly over sanded, clean wood. I know of one professional that applies Cetol exclusively and his work is fabulous.
Cetol comes in four varieties, with the new Natural providing a more golden color resembling the real look of raw teak. You can overcoat any of the other pigmented Cetol finishes with the Gloss for a high gloss exterior finish.
Two Part Wood Urethane Finishes
Another finish to make an appearance in the cruising world are the urethane two-part finishes. Fashioned to replace traditional varnishes, these products have made a mark in the yachting community. Their producers developed these finishes to hold up in tropical conditions for years at the time. One maker, C Tech Marine, boasts that its product Bristol Finish is used on numerous cruise ships, attesting to its beauty and longevity.
