Exterior Wood Finish Test Two-year Update

Two-part varnishes leading in durability as long-term test reaches 24-month mark.

Like spotting land after a long passage, we’re glad to say that the end of our longterm exterior wood finishes test is finally on the horizon. Time, weather, and Southwest Florida’s unrelenting sunshine have clearly taken their toll on the test panels over the last 24 months, and as the evaluation moves into its third year, only 19 of the original 54 test products will continue on in our survival-of-the fittest finish matchup. Given that most wood coatings are rarely expected to last longer than two years in the marine environment—particularly in super-sunny locales—it’s no surprise that we’ve seen more significant changes in the coatings in the last six months than we had in previous checkups.

Bottom photos by Frank Lanier After two years of testing, its apparent that two-part varnishes are the most durable type of exterior wood finish.

Our search for the ideal wood finish—relatively easy to apply, easy to maintain, lasts multiple seasons, and is affordable—began in 2007 when we took a look at the different types of exterior wood finishes on the market, their pros and cons, and how easy they were to apply (one-part varnishes, August 2007; varnish alternatives, October 2007; two-part varnishes, December 2007; teak oils and stains, April 2008). Launched in 2008, the longterm panel test aimed to determine which type of coating offers the best and longest protection and which products stand out among their peers.

We hope the comparison enables readers to decide which finish best matches their own taste, potential labor investment, and wood protection needs. For more on the differences between wood finish types, check out “Wood Finishes 101,” which appears with the online version of this article.

We’ve rated the test products every six months and reported on the coatings’ durability in the May 2009 (six-month checkup), December 2009 (12 months), and January 2011 (18 months) issues. Here, we offer the two-year report on the survivors.

How We’re Testing

Testers applied dozens of exterior wood finishes (22 one-part varnishes, six two-part varnishes, 18 synthetics and satins/varnish alternatives, and eight teak oils and sealers) to small panels of bare solid teak. Each was assigned a number for blind judging and was applied per manufacturer’s instructions. If makers gave a range for the number of coats to apply, testers went with the minimum.

Initial testing rated each product’s ease of application and original gloss and reflective qualities. In the summer of 2008, the test panels were mounted on a wooden rack (aka: “The Rack”), which was set up in an unobstructed area on the roof of the PS workshop in Sarasota, Fla., to ensure that all panels received the same amount of weather exposure. The top part of each panel was covered to create a control area that testers used for comparison over time. Every six months, we disassembled The Rack and rated the panels on how well their coating integrity, gloss, and color had fared over time with constant exposure to the elements.

The test was designed as an endurance test, a fight to the finish, so we have not done any maintenance coats or touchups to the test panels. These products can be expected to have much longer lifespans if they are regularly maintained. (Find tips on keeping your brightwork healthy with the online version of the report.)

How We’re Rating

Testers rate each panel on three longterm performance criteria: coating integrity, gloss retention, and color retention. Excellent and Good coating integrity ratings mean that no maintenance is needed; a Fair indicates that it’s time for a maintenance coat; Poor means the fat lady has sung, and the coating would need to be removed and re-applied. Excellent ratings are given only to those with an uncompromised coating. This time, panels with Poor and Fair- coating integrity were pulled from the test.

Color and gloss retention ratings are relative to the panel’s original finish. Initial gloss and ease of application are relative to the field within each coating category; these were assigned immediately after the panels were coated.

It was tougher to pick Recommended coatings at the two-year mark, as most wood finishes aren’t intended to go that long without maintenance. One-part varnishes that earned PS’s recommendation this go-round were rated Fair for coating integrity (none rated better than Fair ) and had no Poor ratings. Recommended two-part systems rated Good or better for coating integrity with no Poor ratings. No varnish alternatives or teak oils/sealers were recommended at two years.

What We Found

What a difference a season makes! With the exception of a few two-part products, the test coatings had lost their sparkle at the two-year mark. Ratings slipped across the board. The UV abuse had obviously taken its toll, sucking the life out of most of the coatings, particularly the clear finishes.

Those clinging to life with Fair coating integrity are still protecting the wood, but they’ve lost their looks. In the real world, all of the one-part varnish and varnish alternative test panels would be due for a maintenance coat, and some—like HMG K Type Varnish, West Marine WoodPro Plus (rebranded Epifanes Rapidclear), and Ace Spar Varnish—would be overdue.

The biggest overall decline was within the one-part varnish test group: Not a single one rated better than Fair for coating integrity or gloss retention, and nearly half of the test field was retired after this rating round. Just six months before, eight of the 19 products rated Good for coating integrity and six rated Good for gloss retention. In 12 months, seven dropped from an Excellent coating integrity to a Fair.

The one-part varnishes offering the most protection after two years are Detco Crystal, Le Tonkinois Vernis, and Pettit’s Z-Spar Captain’s 2067. However, their extended protection comes with tradeoffs: Detco rated only Fair for application, Le Tonk’s gloss started to slip after one year, and Pettit’s 2067 started losing its original color after 12 months.

One hardware store varnish has surprisingly held its own over the long haul: Minwax Helmsman Spar Urethane. At half the cost of the Recommended one-part varnishes, Minwax slacked in the color retention department, but it has proven its multi-season durability.

Four of the nine varnish alternatives have been voted off The Rack after two years, and none performed well enough to earn our recommendation for two-year wood protection.

Two of the top performers, Interlux Perfection and Cetol Marine Light (with gloss) managed to hold on to their original color well through two years of testing.

The Cetol products are still at the head of the pack, albeit a somewhat mangy-looking pack. The cloudy, opaque look of the Cetol Marine and Marine Light products may not appeal to everyone, but the fact they’ve maintained their color for more than a year is a good example that higher-solids finishes tend to offer better UV protection.

The Cetol Natural (with gloss) test panel fell from a Good coating integrity six months ago to being dropped from testing. Its performance mirrors what we’ve seen in the field: Give it a little loving once a year with a scrubby pad and a fresh coat, and it’ll last the long haul.

It’s taken two years, but the two-part varnishes are finally starting to show their age. Surprisingly, the first products to be dropped from this group are two that performed well in past PS tests: Bristol Finish and Honey Teak. This is likely because the life of a wood finish in Florida is always going to be shorter than in our past test locales in New England.

The other two-parts are still holding up well, with Interlux Perfection and Nautiking Nautithane offering uncompromised protection and better-than-expected gloss after 24 months. Perfection has been reformulated since the test began and is now sold as Perfection Plus.

The “temporarily discontinued” (since 2009) Smith’s Five Year Clear has also proven to be a top-notch finish, but it’s not available at this time.

While HMG Acrythane XSC didn’t earn our Recommendation this time, it was a top 18-month finish, it still looks good, and it costs less than the Nautithane.

Conclusions

After two years of testing, we’ve come to accept that perhaps there’s no Holy Grail of exterior wood finishes. It would appear, unfortunately, that we can’t have it all: easy to apply, easy to maintain, long-lasting protection, and a budget-friendly price tag. The reality is that, like much in life, wood protection is all about compromise and balancing your needs with your wants.

There’s no one-size-fits-all solution, and the boat owner who finds gratification in the wet, glossy look of a two-part varnish borne of painstaking preparation and careful application will weigh our test data much differently than the one who regards brightwork maintenance as a masochistic endeavor. For the latter, we recommend seeking out a varnish alternative (easy to apply, easy to maintain) that suits your tastes. With modest maintenance, the Cetol products with gloss overcoats have proven to be the most durable.

For areas where slippery-when-wet coatings won’t do, Cetol Natural (without gloss overcoat) or our top-pick teak oil, Star brite’s Tropical Teak Sealer (classic teak) should be considered. The Star brite will need to be reapplied every three or four months.

If you’re looking for a harder, more abrasion-resistant finish that’ll make it past the year mark, check out the top one-part varnishes like Detco Crystal or Pettit’s Z-Spar Captain’s 2067. Boat owners in sailing areas that see less sunshine than our Florida test site should also consider Pettit’s Flagship 2015 or Captain’s 1015. One-part varnishes require a little more work upfront and quick attention when they are scratched or dinged, but they also offer a more traditional, high-gloss look. The one-part varnishes in our test slipped dramatically after a year and half, so we suggest an annual maintenance coat, whether they look like they need it or not.

As this test has shown, when it comes to long-lasting protection and gloss, two-part varnishes just can’t be beat. They may be a pain to apply—and should you let the coating fail, you had better invest in a heat gun—but their durability is unmatched.

The top two-part after two years of testing was Interlux Perfection. Because we’ve not yet tested the reformulated Perfection, the top pick honors go to Nautiking’s Nautithane. While its price tag ($120 per quart kit) is a bit hard for most of us to swallow, Nautithane earned across-the-board Good ratings after two years.

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