Interior plywood panels

Discussion in 'Materials' started by goodwilltoall, Jan 1, 2018.

  1. goodwilltoall
    Joined: Jul 2010
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    goodwilltoall Senior Member

    Greetings,

    Been using BC plywood and like the cheerful, happy look of the grain and its light color so would like to use inside at hull sides with 1x hardwood trim at boat frames.

    Problem is overtime it begins to darken and get a a reddish hue which I find unappealing, reminds me of something old and musty. Coated plywood bulkheads with epoxy a few years ago that got so dark it was hard to discern even a pattern in the grain. This was done using an epoxy with a a very dark brown hardener however, did areas this past summer with a much clearer formula and its amazing how quickly it changes.

    Is there another species that has wp glue, light colored, lively grain, and somewhat readily available or any finish that can keep the wood color stable?
     
  2. gonzo
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    gonzo Senior Member

    Wood normally changes color with age. What species of plywood are you using? Is it a pine or fir?
     
  3. goodwilltoall
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    goodwilltoall Senior Member

    BC plywood from home depot or lowes most popular around . I have seen cherry get get dark like this but over decades. Will check again but I believe Chipotle restaurants use it as part of thier decor
     
  4. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member


    As gonzo said all woods darken with age. Cherry is one of the fastest, I often "stain" cherry by leaving it exposed to sunlight for a few minutes. Maple ages to a pale tan, but isn't usually available from the big orange or blue box stores

    All clear finishes darken with age. Epoxy, shellac and lin seed oil are the quickest to darken. Polyurethane and automotive acrylic stay clear the longest, but are very difficult to apply and maintain.

    Staining fir with a near whitewash should keep it light for many years. Pure white stain looks artificial while a peach colored stain retains the natural wood tone. If you choose to lightwash, then practice on a large sheet as it is more difficult to achieve a uniform color than with typical brown stain.
     
  5. PAR
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    PAR Yacht Designer/Builder

    BC plywood is just the face finish quality and has no bearing on the panel construction, glue type and suitability in a boat. The APA grades suitable for use in a boat are "Exterior" and "AA or AB Marine" I'm fairly sure you can get BC marine, though I've never seen it. These are built to similar standards (PS1-95), though the marine has better face veneers and fewer defects.

    The above advice is correct, all wood darkens with UV exposure, though there are ways to greatly slow this process. Of course, paint or other non-transparent material works the best, but if you want a "bright" finish, 2 part polyurethanes (LPU's) and 2 or 3 pack acrylic urethane work best. Both of these are difficult to apply well, but are durable and long lived. They're difficult to repair and usually need to be stripped to refinish properly. Next up are the single part polyurethanes, which are more forgiving to apply and slightly better to repair. The modified varnishes are next followed by regular varnishes. These are fairly easy to repair if you "catch it" in time. Brightly finished wood is the most difficult finish to live with in an outdoor environment, let alone the marine environment. There's no short cut to this, you have to want it, maintain it and employ unique care, to keep it looking good and after all the care, you'll still have to redo it every few years.
     
  6. goodwilltoall
    Joined: Jul 2010
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    goodwilltoall Senior Member

    Yes, the ply is bc rated exterior. I would assume its pine because of dark it got. It will be used at interior and was wanting a clear finish. Are 2 part polyurethane or acyrlic urethane able to be applied brush and sand?

    PS planning on low gloss/low sheen.
     
  7. Blueknarr
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    Blueknarr Senior Member


    I'm guessing it's for, because for darkens more than pine.

    The really good supper clear multi-part acrylics and urathanes are packaged to be professionally sprayed and are too thin to brush flawlessly. Pettit sells a doy 2-part marine clear. I have not been tempted to use it. Have spent many hours removing others botched applications.

    I strongly recommend standing a full sheet of ply up and practice with a two inch brush.

    Good luck
     

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

    Is the plywood rated "Exterior" or "Exposure 1 Exterior", as there's a significant difference. All APA plywood rated as Exterior or Exposure 1, is Douglas fir with a WBP glue. You can use an acrylic urethane, but hand applications will not look very well for a paint that's designed to be sprayed. The Pettit product is a polyurethane and better than the automotive grades for hand application, but still not very good, unless done in perfect application condisions and using ideal techniques.
     
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