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I'm thinking of using exterior polyurethane for my exterior furnishing. I'm planning to use Minwax Helmsman Spar Urethane Indoor/Outdoor Wood Finish. Is this the best one to use or there are better options within its price range?

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  • Hi, welcome to StackExchange. "within its price range" I'm glad you added that because otherwise the answer to this would be a resounding "YES!". Unfortunately, and rather inevitably, the REALLY good alternatives are in a different price category entirely. I dump on Minwax stuff all the time (it's cheap for a reason, and their tech people seem not to know squat about their own products) but not singling it out for a change — the bald truth is that most consumer-level spar varnishes are not worth the name 'spar varnish' and simply don't hold up well in challenging conditions.
    – Graphus
    Jul 13, 2022 at 3:29
  • Just to check, you do know what you're singing up for by finishing exterior projects with varnish? (Strong colour, high gloss, regular upkeep every couple/few years.) Although the refinishing window is greatly extended if you use a proper marine-grade varnish that will hold up well to anything weather can throw at it, you're still looking at touchups or revarnishing periodically, for the life of the furniture, which is not something to take on lightly.
    – Graphus
    Jul 13, 2022 at 3:55
  • Hello @Graphus, thank you for your hospitality and for your response. My exterior projects are wooden tables and chairs. I don't have a preference maybe what I need is a durable finish that looks beautiful because it is for our Airbnb. Can you give me an alternative that has a higher price but is not super expensive? I really appreciate you!
    – TPH John
    Jul 13, 2022 at 14:49
  • There are numerous optional products and finishing schedules (multi-step, using more than one thing) suitable to exterior furniture, for any given set of variables inc. wood type, climate, full exposure versus partial cover, desired looks and/or feel, and not least, ease of application. Many alternatives have the advantage that they're easier (or downright easy) to apply, much better suited to someone without finishing experience. FYI it's actually quite challenging to apply varnish to a high standard, even with experience (varnish is given as a pro-only finish in some old sources). [contd]
    – Graphus
    Jul 13, 2022 at 20:15
  • Given the difficulty in varnishing for the novice, can you reconstruct the research steps that led to the choice of spar varnish in the first place, then Helmsman specifically? Was the latter based mainly or entirely on its price? Direct price comparisons finish to finish can sometimes be of limited use, since higher-priced products (and sometimes MUCH more expensive products) can last 2-3x longer than a cheap alternative, may require fewer coats so you actually use less product, or, innately have better coverage. So choosing a finish for outdoor projects can be a complex, interwoven process.
    – Graphus
    Jul 13, 2022 at 20:23

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welcome to the group.

Some years ago, Fine Woodworking had an article on Door finishes which caught my eye, being in Texas with what seems like a hotter sun than elsewhere.

As others point out, "best" is difficult to assess at times, and maybe not much more than a lot of opinions outside rigorous testing.

To shorten the story, you may dig up the article, but their bottom line was using a penetrating epoxy for one or more base coats, then any Spar Varnish or paint if you wanted.

For me, I refinished my door of three years that had flaking varnish where it had not already sloughed off, using the epoxy (recommended, but no longer available from that company), and a final varnish coat. I'm just now repeating after 15 years. (Could be argued I should have done it at 10, but still far longer than the first finish.) The finish performed far better than any film alone, in my opinion/testing. Cost is likely cheaper if you factor all your work time, and repeating on a yearly or bi-yearly basis.

The reasoning, in a nutshell, was given that because the epoxy not only seals the pores of the wood, but also provides a consistent elasticity for a base.

Regardless of what you choose, I would strongly suggest looking at marine quality products. Good luck!

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