Exposure Test Results: Varnishes, Teak Oils, and Other Exterior Wood Coatings
Practical Sailor testers rate test panels on gloss and color retention and coating integrity.
Science and technology have turned the once-simple task of choosing a wood coating into a brain-numbing chore best suited for those with a degree in chemistry. From the basic, old-school tung oil or spar varnish, coatings have evolved into synthetic concoctions that last longer, protect the wood better, and are easier to apply. Their formulas include blockers for UV rays, additives we can’t pronounce, and pigments that look more like paint.
To help navigate this coatings evolution, we mounted a long-term test of exterior wood coatings in 2007 in search of the ideal finish among the tried-and-true and the market newcomers. We refrained from limiting the test to a single type of exterior coating and are instead looking for an overall all-star. We’ve kept the test field broken into type categories—one-part varnishes, two-part varnishes, synthetics and treatments, and sealers and oils—which hopefully will make it easier to digest and also will allow an apples-to-apples and apples-to-oranges comparisons. Our goal is to find an exterior wood finish that is relatively easy to apply, easy to maintain, lasts for multiple seasons, and won’t break the bank.
This long-term exposure test began with reports on the application and original finish of more than 50 products in the August 2007 (one-part test varnishes), October 2007 (varnish alternatives), December 2007 (two-part varnishes), and April 2008 (teak oils and stains) issues. Our first evaluation of the coatings’ durability was reported in May 2009. Six-months later, testers returned to the test rack to see how the finishes fared after a year in Florida.
How We Tested
Testers are evaluating the wood coatings based on three main criteria: ease of application; the integrity of its gloss and appearance; and how it fares over time under real-world conditions. The results, listed in the Value Guides on pages 14 and 15, will determine which type of coating offers the best and longest protection, and they will show which products stand out among their peers.
Each product was applied per manufacturers’ instructions to a section of bare solid teak, and each panel was assigned a number to ensure blind judging.
Testers rated each product’s ease of application—how smoothly it went on, how complete the instructions were, and how simple the process was. With the varnishes, testers also evaluated the original gloss’ shine and reflective qualities. Coatings intended to have matte or semi-gloss finishes, like teak oils and stains, received no "original gloss" rating.
In summer 2008, the panels were mounted on a rack in an unobstructed area on the roof of the Practical Sailor workshop in Sarasota, Fla. The rack was set up at a 45-degree angle to ensure that all panels received the same amount of exposure to the weather and sun. The top part of each panel was covered, giving testers a control area to compare the weathered area and original finish over time.
How We Rated
After a year exposed to the Florida weather, the finished panels were rated for coating integrity, color retention, and gloss retention. Coating integrity ratings took into account the entire panel. Excellent ratings were given only to those with a totally uncompromised coating. Panels with Poor ratings were pulled from the test.
Color and gloss retention ratings are relative to the panel’s original finish, not the finish of other coatings. So although a panel may have had only a Fair rating for its initial gloss, if it maintained that same level of gloss for six months, it earned an Excellent for gloss retention.
Initial gloss and ease of application are relative to the field within each coating category, and these were assigned immediately after the panels were coated.
A year into our long-term exposure test, 20 of the original 22 one-part varnishes are still in the running. In real-world application, those rated "Fair" for coating integrity (See Value Guide, page 14) would be due for a maintenance coat, but none have failed to the point that would make a fresh coat or touch-ups difficult.
Three panels dropped from Excellent to Fair ratings in coating integrity at the one-year mark: Pettit Bak V-Spar, Interlux Jet Speed varnish, and Le Tonkinois No. 1. The V-Spar coating appears to have simply worn away—no cracking or peeling—so a maintenance coat would require minimal sanding. While it fared well in past tests and in the six-month checkup for this test, the Interlux Jet Speed is not recommended by makers for use on exterior wood unless an overcoat is applied.
The Jet Speed and Le Tonkinois No. 1 also were among a handful of finishes that lost most of their luster, earning a "Poor" for gloss retention. These two, along with Le Tonkinois Bio with Vernis overcoat and Le Tonkinois Vernis, showed tiny, barely perceptible cracks in the coating. The finish, upon close inspection, looked very much like dry, winter-ravaged skin.
Le Tonkinois distributor, American Rope & Tar, recommends re-coating the finish as soon as it begins to look dull: "Le Tonkinois is not a no-maintenance varnish, but is a low-maintenance varnish," they explained.
The varnish panels that saw the biggest change in color after a year in the Florida sun were those finished with Coelan (with primer) and Interlux’s Schooner. The Coelan panel, originally a medium brown color, took on a reddish-amber hue. The coating is still very much intact, and its gloss is still excellent. (We would expect no less of a varnish that costs nearly $150 per kit and requires a primer.) The Schooner lightened from a warm golden brown to a light amber.
Since our test began, Pettit discontinued its Bak V-Spar and Interlux replaced Schooner and Goldspar Clear and reformulated Perfection, boosting UV protection and making other performance tweaks. The new coatings hit store shelves this fall and are being sold as Schooner Gold, Compass, and Perfection Plus. The Compass is being marketed as a fast-dry finish with a three-hour re-coat time. These will be included in future tests.
While most of the varnishes are still performing well after a year, testers’ top picks so far are Epifanes’ Clear High Gloss and Wood Finish Gloss, and Pettit’s Z-Spar 2015 Flagship and Captain’s 1015 Traditional Amber. They also were impressed with Interlux Goldspar Clear and Coelan, but the Goldspar is no longer available and the Coelan’s significant color change dropped it from the top ranking. Those finishes that are skating on thin ice going into the next round of testing are Interlux Jet Speed, Le Tonkinois No. 1 and Pettit Bak V-Spar.
Bottom line: The Best Choice varnishes after a year are Pettit’s Clear High Gloss and its Wood Finish. The Budget Buy one-part varnish is the oil-based Ace Spar Varnish Gloss (16373), which rated "Good" in every test and has a dirt-cheap price: $8 per quart.
Not surprisingly, all six of the original contestants still remain in the two-part varnish matchup. There were, however, a few surprises in this category, which is typically thought to offer the best single-application longevity compared to one-part varnishes and synthetics or oils.
C-Tech Marine’s Bristol Finish and Signature Finishes’ Honey Teak two-part varnishes have generally tested quite well in past tests. But after a year in this long-term test, both are already showing signs of compromised coating integrity.
The Honey Teak is failing along the panel edges. On a boat, these areas would need to be cleaned and sanded well before any touch-up would be possible. The failure along the panel sides could possibly be attributed to thinner application to those areas. Maker Signature Finishes also was surprised by the early failure. "Premature failure is generally due to an insufficient amount of the honey base, which contains all the UV" protection, maker Tom Fabula explained. "Thank goodness this product can be spot repaired invisibly, and a coat of the honey base on top of previous clear topcoats will bring the longevity up to par."
The Bristol finish is pulling away at the bottom edge, and there are a few small bare spots on the panel front. These appear to be nicks that would be easily repaired with a touch-up routine. (See page 18 for more on touching up finishes and maintenance coats.) The Honey Teak and Bristol both have shown excellent gloss and color retention, however.
Testers’ overall favorites in this group after one year are Interlux Perfection, Nautiking Nautithane, and the Smith & Co. Five-Year Clear. None of these two-part systems are cheap, but they should last longer than other finishes, so theoretically, you get as much bang for your buck because re-coats will be required less often than less-expensive coatings.
Bottom line: The Perfection and Nautithane are in the same price range, but Perfection stocks are being phased out; we’re hopeful the formulation performs as well. Nautithane also edged out Smith & Co., only slightly, in integrity, giving it our top pick among these two-parters.
Varnish Alternatives / Teak Oils
As expected, the test fields to see the most changes to their rosters in the last year were varnish alternatives, teak oils, and teak sealers: Of the original 17 products, only 12 teak treatments made it to the one-year checkup, and most of those were the two-step systems like Cetol that included a clear gloss overcoat. The group of eight teak oils and sealers had been whittled down to one coming in to the one year test.
Teak oils are not meant to be multi-season coatings, but Star brite Tropical Teak Sealer held its own at the six-month mark. After a year of exposure, though, the panel is well past due for a re-coat and will be dropped from the test rack.
The panel finished with TeaQua, a pigmented sealer, also is in need of re-coating. In the areas where the coating failed, black mildew spots appeared, so this panel would require a bit more effort to freshen the coating. It too should be re-coated well before the year mark and will be dropped from the test rack.
The Cetol panels, for the most part, are still going strong. The panels coated with Interlux Sikkens Cetol Marine and a gloss topcoat and Marine Light with a gloss overcoat both rated very well. The coating integrity is flawless and the gloss unchanged; however, these finishes were initially "muddy" and have retained that quality. Aesthetically, testers prefer the clear look of the Cetol Natural Teak, but it doesn’t seem to offer as much protection as its pigmented sister finishes. The Cetol Natural sans gloss overcoat has begun failing at the panel edges.
Another pigmented synthetic, WoodPlus Marine, has shown acceptable protection and performance.
Bottom line: The results are consistent with past tests: Liking Cetol’s cloudy finish is a subjective matter, but when it comes to single-application longevity, the Cetol Marine and Marine Light with gloss reign supreme among varnish alternatives.
Competition for the title of "ideal wood coating" remains strong between coatings types at the one-year mark. While varnish in general appears to offer better durability, some synthetic systems—namely those with protective overcoats—are holding their own, especially when it comes to UV protection and color retention. Teak oils can’t be expected to last the longhaul on a single application, but Star brite’s teak sealer survived a surprisingly long time.
"Ideal" is a subjective term. To determine what the ideal finish for your boat is, decide what time and energy investment you can make up front for application, how often you realistically will apply maintenance coats, and where and how you plan to use the boat. (See "DIYer Notebook" on page 18.)
Traditionalists who want that high-gloss, wet look and are willing to put forth a little extra effort in application would do well with any of the recommended two-part varnishes. These hard coatings have proven durable and most likely won’t need re-coating for years. Our favorite at the one-year mark is the Nautiking Nautithane.
If you find the two-part kit prices (and application headaches) to be too much but still want a good gloss, choose from one of the recommended or budget buy one-part varnishes or varnish alternatives with an overcoat.
The Cetol products offer the best option for taking the middle ground between good looks and durability. They won’t have the classic look of varnish, but for 25 percent of the labor, you get a similar result.
For spots where a slippery-when-wet finish is not feasible, check out the top synthetics or teak sealer. Our favorite for coating decks is still Semco. It will need to be re-applied every few months, but done regularly, the process should be easy.
Any of the recommended products listed in the Value Guides on pages 14-15 would serve well for a year or more. Stay tuned for the two-year checkup next winter.