Choosing a Varnish for Your Boat's Brightwork

Published: 27th November 2009
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Varnishes have been applied to protect and maintain teak on boats for hundreds of years. History shows that varnishes used in the 1700s are very akin to what is used today. The coatings allow for the attractiveness of the wood to be viewed while offering protection from the elements. The luster attained after careful application will vary from a soft patina to a high gloss finish akin to fine furniture.

Assuming you want to protect and embellish your boat's exterior wood, how do you select among the astounding variety of finishes? Knowing completely that this is as big a deal as debating the benefits of power vs. sailboats, we nonetheless offer the following observations.

What is a Varnish

A varnish is a liquid finish commonly used to treat teak. Its primary components are oils. resins, solvents, dryers and ultra-violet additives. The components are used in different proportions to give the best appearance and protection.


Oils generally hold the new look and grain of the teak more than the other products because they penetrate deep into the teak fibers and do not create as much of a surface finish. Wood oils are available in colours ranking from crystal clear to gold to dark brown. As with all teak finish, multiple coats generally lead in a more uniform finish and greater length of service. We find oil to be the easiest to apply, since surface blemishes are not as apparent in the ultimate outcome. This doesn't mean, however, that slapping four coats of wood oil on raw teak will develop a great finish. You'll also find that oil's light consistency makes masking to protect surrounding gel coat and painted surfaces almost as crucial with oil as with varnish. Clean, sanded teak with several coats of oil can 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 complicated finish consisting of oil, solvents and thinners, resins, dryers and additives. By varying the ratios of the elements and by blending ultra-violet inhibitors and other secret components, producers make varnishes with widely varied characteristics. Varnishes can have a high gloss or matte visual aspect, can be produced to be super hard for walked-on surfaces and can deviate in color.

The 2 most common varieties of varnishes are natural resin varnishes such as tung oil and oil-modified polyurethane varnishes. Natural tung oil varnishes are great for interior or exterior use and provide the traditional golden teak appearance. Oil modified polyurethanes tend to be more clear, allowing the color of the teak to shine through.

Recent varnishes, provide better durability in the worst of environments such as the hot, tropical sunlight. Teak moves, and since it is a previously living thing, it expands and contracts with even small fluctuations in temperature and humidity. Premium varnishes contend with this unstable material employing high quality Oils and resins and a greater percentage of solid components, providing a longer lasting, more flexible coating with a higher gloss.

Six to ten coats is usually required to get a quality look. A good base coat, annually cared-for with maintenance coats, will give the ultimate in appearance, length of service and protection. Despite the original effort (up to 10 coats are common) nothing looks better than exterior brightwork finished with gloss varnish.

Interlux's Original 90 is just one variety of traditional spar varnishes on the market.

Synthetic Teak Finishes

These coatings gained popularity with cruisers in Florida and the Bahamas searching for ultra-violet resistant low-maintenance brightwork. Developed for simplicity and speed, these finishes have uncommon durability for exterior use, are easy to apply and look comparatively good. Some varnishes such as Interlux Goldspar and Schooner are produced with no pigment so the teak's natural appearance is protected. Full gloss and depth vs. convenience is the trade-off with these finishes, but ease-of-use and time savings can more than compensate. Applying synthetic finishes is akin to teak oil, where you can apply it immediately over sanded, clean wood.

I know of one professional that applies Cetol exclusively and his work is fabulous.

Cetol comes in four forms, with the new Natural allowing for a more golden color like the real look of raw teak. You can overcoat any of the other pigmented Cetol finishes with the Gloss for a shiny exterior finish.

Two Part Wood Urethane Finishes

Another product to show up in the cruising world are the urethane two-part finishes. Designed to replace varnishes, these products have made a mark in the boating community. Their producers developed these finishes to survive 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.

Mike Dickens, the author, is a liveaboard boat owner and owner/Broker of Paradise Yachts in Florida USA.

Paradise Yachts offers used quality yachts to customers worldwide.

Visit the Paradise Yachts website to view our selection of Used Trawlers, Used Motor Yachts, and Used Sailboats for Sale

National and international sales. We ship Used Yachts and Used Boats worldwide. Located in Florida, USA. 904/556-9431

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