I have a friend who’s fascinated with live edge. He wants to replace the ‘serving bar’ at his boat dock cabana. Obviously, the cabana is near water and exposed to the elements. However, it’s under roof and receives minimal, if any, direct sun.
He loves cherry; I was able to find some decent slabs and have prepped for the final installation if a few weeks. He wants to finish with an oil of some sort, but I am convinced that he’d be applying oil every month to protect the wood.
Is there an oil that would provide sufficient protection for fine wood like cherry in such an environment? I am thinking that he’s better off with polyurethane or possibly and epoxy finish.
I’ve tried to upload photos for a better explanation, but for the life of me I cannot create a jpeg or pdf that is under the 3MB file limit
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Cherry boules are wonderful; I have several in my home. They're lightly finished with a Danish oil, and not abused, and they stay just fine. But they're indoors, and they're not subject to the kinds of accidents that happen around bar counters.
The bare cherry grain is beautiful, and if it's truly well protected from the elements and gets very little direct sun, you could just leave it untreated. Once a year or so if it greys a little, give it a mild bleach wash to lighten it up and perhaps a light sanding with fine paper.
Unfinished, of course, it will likely get blotched from usage, especially if it's used as a bar - grease stains, spilled wine, etc. So to prevent that, if you decide to use a finish polyurethane would probably be OK if what you say about its exposure is true. In the off-season, consider a waterproof cover.
Spar varnish for boats would probably be best. My advice is to take your question to a boating forum.
Epifanes seems to have won out in the torture test ..
Torture test for outdoor finishes: The end
Mother Nature: 1, outdoor finishes: 0.
By Mark Schofield May 18, 2011
In the June 2009 issue of Fine Woodworking magazine (#205), Tom Begnal wrote an article called “Torture Test for Outdoor Finishes” where he described how he prepared sample boards from five different types of wood (mahogany, pine, white oak, ipe and cedar) and finished them with five different kinds of clear, exterior finish. A set of boards were then sent to spend a year in the damp U.S. Northwest, another set baked in New Mexico, a third suffered in the heat and humidity of Louisiana, while the fourth set sat up on the roof of Fine Woodworking’s office.
The boards finished with Epifanes, a Dutch marine varnish, and those that were first treated with an epoxy sealer and then finished with Epifanes as shown by Sean Clarke in issue #178 “A Durable Exterior Finish” came through almost unscathed, a hardware store spar varnish had mixed results, while those boards finished with a water-based polyurethane and those finished with a penetrating oil finish did not survive their year-long test.
At the risk of hijacking this thread, I'll give you my thoughts on Epifanes. I speak as a long-time veteran of classic boat restoration and maintenance. Not as a professional, but over time I've accumulated the scars (I also recommended a more lightweight approach above).
Almost all marine spar varnishes come pre-thinned to a brushing consistency. You put it on right out of the can, if possible, although sometimes you may thin it out a bit, as little as possible depending on ambient conditions, in order to get it to brush out nicely and level itself.
Epifanes is different: in the can it's about as thick as a heavy motor oil, having none of the volatile thinning agents that others come with. You then have to thin it yourself with their thinning agent to a suitable consistency for application. How much you put in varies according to the ambient conditions of the day: the temperature, the humidity, the breeze, the time of day, the sunlight or the shade. You have to have used it a lot to learn how to get it right, and for that reason it's thought of according to boatyard workers and professional painters and varnishers as an expert's product. I've used it myself, of course, but I've never grown to like it. Over-thin it and you lose UV protection, under-thin it and it sags and droops and you can't keep a 'wet edge' with the brush. Still, it definitely gives you the best UV protection you can find. So there you are.
A warning though - once you start down the varnish line, however, you can never get off that train. We have a saying: 'There's no such thing as the last coat of varnish.' ;-)
And that's all I have to say.
6 months ago I made several restaurant tables out of ash that were meant to be used outdoor. They spent all this time exposed to rain and direct sunlight and survived perfectly to this date after a rainy summer. They were finished with 3 coats of rust-oleum spar varnish, nothing fancy . I use Epiphanes on the boat and the main difference is that it requires thinning for the first coats or after the content has been exposed to air for some period of time.
I would advise 3-coats epoxy and 5-coats of Epifanes (or a comparable product). The epoxy seals it from moisture. The varnish provides UV protection for the epoxy and wood. This will last you a while, but will still require varnishing every few years. And if you don't like the glossy finish, Epifanes also has a semi-matt that you would apply as your two final coats.