Refinishing Interior Wood

Discussion in 'Wooden Boat Building and Restoration' started by Abinoone, Sep 12, 2015.

  1. Abinoone
    Joined: Sep 2015
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    Location: Buffalo, NY

    Abinoone New Member

    Hello,
    I have a 40 year old Bristol 32 sloop and plan to refinish the cabin interior. The bulkheads, and cabinet panels are mahogany veneer plywood, and the cabinet frames and drawers are solid mahogany; there also is a little teak trim. All of the wood was originally varnished. I'm currently hand sanding all surfaces with 220 grit sandpaper to prepare for the new finish.

    My question is what type of finish coatings should I use? I visited my local marine supply store where I found a variety of (expensive) marine varnishes and urethanes - Epifanes, Interlux, Bristol, etc. at up to $65 per quart, my refinishing job could become fairly expensive for the 8 or so coats I plan to apply! For a nice, attractive, and long lasting finish do I really need to use one of these marine finishes or would something like Minwax Helmsman Spar urethane ($16/quart) do just as well? I completely understand the need to use high quality, high UV resistant finishes on exterior brightwork (I use Sikkens Cetol Natural on my exterior teak) but for interior cabin wood is it really necessary or advisable?

    Any advice would be greatly appreciated!
     
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Welcome to the forum.

    The Minwax Spar urethane doesn't hold up very well, at least in my tropical environment. As a rule, you have two basic choices; urethane and alkyd (real varnish). Real varnish takes some skill to apply well, requires a long time to dry (24 hours +), isn't as hard or durable as the urethanes but it can also be easily touched up and repaired if necessary later. The urethanes are harder, retain gloss longer, have better UV resistance and are easier to apply (the single part versions), but they tend to be more problematic come time to repair or touch up. The two parts urethanes can be complicated to get right, with wetting agents, different hardeners, special solvents, etc., but once you get a handle on what they are, they're really good. The urethanes dry much quicker. The stuff I use can be cured enough to sand in a couple of hours.

    Clear finishes on wood are the most difficult to live with, requiring maintenance and touch up, to keep them in good condition. A scratch in varnish can be sanded, feathered and more "flowed" into the repair for a nice touch up. Urethane can be as well, but the window to do this is quite small and is the damage severe, you might have to start from scratch (remove it all) to get satisfactory results.

    Most professionals have found using the "good stuff" pays for itself in the long run, with longer times between re-coatings and it generally stays looking good longer. The stuff I use is a two part urethane and is costs about $250 a gallon, but it does perform well. I spray it, so finish equipment becomes an issue too. As to which brand, well this is subject to a fair bit of familiarity and supposition. The major brands all have about the same solids and UV inhibitors content, so you'll be safe with these. On the inside of a boat, the idea of cheaper brand seems reasonable, but what most find is this is accurate, except in the places where direct sunlight comes through a port and burns the exposed surfaces, at a much faster rate than surrounding areas. This is why I prefer to use the good stuff, even inside the boat.
     
  3. Abinoone
    Joined: Sep 2015
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    Abinoone New Member

    Many thanks for your reply PAR! I live/sail in the Great Lakes, where our summers are mild and season (unfortunately) short - basically 3 months of water time. The rest of the year my boat sits in a cradle under cover. Given these conditions would you still recommend using "the good stuff" for the interior? My refinishing skills are amateur, so I'd most likely opt for ease of application (foam or natural brush) and the one part erethane.

    Thanks again for your experienced guidance.
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    You can get by with Minwax, if she's under cover, though it's one of the lower grades of finish available. Foam brushes will offer a better finish than a brush, for the novice.
     
  5. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    You probably need to know what the current coating is, to pick the suitable finish. If by some chance it is shellac, you have problems re-coating that with alkyd or polyurethane, it will "alligator". If you can dissolve the present finish with what you folk call "denatured alcohol" it is shellac, which needs special prep to be able to use PU or Alkyd. If it is Alkyd, PU does not adhere that well to it, my guess is it would probably be PU, and I'd use that again.
     
  6. Jammer Six

    Jammer Six Previous Member

    Like everything else, it depends.

    This depends on how often you'll repeat this task, how often you leave the boat exposed, and what the weather is like.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    It is the interior, Jammer.
     
  8. Jammer Six

    Jammer Six Previous Member

    Doh!

    Of course. Sorry, I got sidetracked by the word "varnish".

    In that case, I'd say that most brands would do, and I wouldn't use a million dollar brand unless I could charge for it.
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    More Jammer foolishness. It's not of a matter of how often you "repeat this task", because you will. How often depends on care and product choices, but you can guarantee you will need to "repeat this task". Given reasonable care, just some touch up and an eventual redo, or with less care, major repairs and/or redo.

    My previous post assumed an alkyd, which would have been era appropriate for a Bristol, though it could have been "up graded" since, most stuck with varnish until recent years, where the polyurethanes started to rise up.
     
  10. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    I'm with you PAR on assuming at the age of the boat, it would originally have been an alkyd 'traditional' varnish. Just possible it was a one pack, which were popular in the 70s' though, although I know two pack polyurethanes that date from the late 50s'. So that only leaves alkyd or one pack poly unless it is stripped right back, at least I would not take the risk of a reaction with any other type. Be surprised if it is French polish (shellac) as that water marks so easily it would be heavily marked all over by now....;)
     
  11. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Plenty of clear acrylics around today, which are quite durable, and will happily go over most older finishes, though they dry very clear and not the amber of PU or Alkyd, and they don't darken with age either, but they don't have the same flow, and are inclined to leave more brush marks. Big advantage is the low odour. You could get high painting with solvent thinned stuff in a confined space, and the odours linger for up to a month. Isn't solvent thinned paint banned in California, e.g. ? But I hate clear coating anything, much easier to use pigmented finishes. And in a marginally lit confined space, light colours are a blessing.
     
  12. Jammer Six

    Jammer Six Previous Member

    Yee gods.

    California frequently makes me shake my head.
     
  13. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Solvent based paints are available in California, though commercial use is being phased out. The acrylic urethanes are still used there, but the good LPU's have numbered days left. The straight acrylics don't wear as well, less gloss retention, the color is all wrong if attempting to match something and generally aren't up the attributes of the solvent based finishes, though they're getting better, especially in the last few years.

    Shellac finishes wouldn't be typical on a Bristol of that vintage, though certainly possible as a bedding or sealant. Both shellac and the old single part polyurethanes would have died a horrible death by now if redone in the 70's or 80's, leaving little more than a flaking, peeling mess to clean up. These finishes are pretty easy to identify by their smell when sanded or by peeling a hunk off and having a look with a good glass or microscope. Shellac's sensitivity to petroleum products makes it easy to figure out and one of the reasons it's not used often as a finish on boats.
     
  14. Jammer Six

    Jammer Six Previous Member

    Or alchohol.
     

  15. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    There's not a lot of alcohol tossed around the inside of a boat, except maybe yours, though petroleum products should be expected on a powerboat, of course except yours.
     
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