Nitro v. Poly - Expert Advice Needed PLease

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Griff, Oct 5, 2006.

  1. Griff

    Griff Member

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    After visitng Reranch and Buildyourownguitar and Projectguitar a few times, and not being overly bright, I am still a little confused about which type of final clear coat to put on my project guitar. The guitar is alder and is being painted opaque BTW. No fancy pants French polish for me - waaaay beyond my ability.

    Can somebody here answer a few questions for me?

    The preferred topcoat seems to be Nitro. Why? Does it shine up better? Does it sound better than Poly? What is it about Nitro that makes it better?

    Poly seems to be much easier to apply - carefully use a brush and some sand paper. I've refinished some tables over the years and always coated them with Poly. They look nice and shiney and have lasted for, well, years. Why shouldn't I use poly on my guitar? Does it crack or check easier than Nitro? Does it affect the tone more, or worse, than Nitro?

    Can some of you wood experts please school me on Nitro v. Poly finishes?

    Thanks in advance for all thoughts and comments.
     
  2. Festus

    Festus Supporting Member

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    First off, I'm not an expert on finishes. I have done a few guitars in the past, but it's been a while. Used both laquer and urethane. Urethane or Poly is a lot easier to apply. Poly is definitely a more durable finish than Nitro.

    I guess if I had a choice when buying a guitar, I'd prefer a nitro finish. It seems a bit more alive than a guitar with a polyester finish. Nitro finishes tend to be thinner than poly as well, so that could be why a guitar sounds better to my ear than the same guitar with a poly finish. I've got guitars with poly finishes that I really like, too, so the finish isn't the only factor in what makes a guitar "right".

    You've got to weigh the pros and cons of both to see which makes more sense. If the guitar is going to get beat up pretty regularly, then a poly finish would probably be the way to go. If you're not worried about guitar abuse and have the time and patience, then nitro could be the way to go.
     
  3. paintguy

    paintguy Long Hair Hippy Freak Silver Supporting Member

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    I split the two and use acrylic urethane. Right in the middle of nitro and poly.
     
  4. Jack Briggs

    Jack Briggs Member

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    First you've got to know what you're talking about when you say 'Poly'. Do you mean polyester? Polyurethane? Both very different both in feel and application. Polyesters (help me out here, paintguy!) are almost, if not always catalyzed. This means that, like epoxy they are a 2-part coating consisting of a resin and a hardener. Your pot life is limited. Also because it hardens by chemical reaction and not solvent evaporation, you'd better be good with the particular gun you're using because you don't really get a second chance. Catalyzed finishes are also a bit tougher to buff out.

    Polyurethanes can be brushed on, wiped on or sprayed on. Some are catalyzed like poyesters. Personally I would rather play a polyester finished neck than polyurethane, simply because of the latter's 'plasticky' feel. Polyester necks can feel almost as smooth as nitro, which is my preference because of the relative ease of application and it's about the thinnest. Nitro topcoats buff out easiest, probably because that finish is not quite as resilient and scratch-resistant as any catalyzed or polyurethane-type finish. The thing to remember when doing any sanding or buffing of any surface is that you're scratching the surface in increasingly finer scratch patterns to where they're not at all visible to the naked eye. This looks like absolute flatness and gloss. (It's an illusion!) ;)
     
  5. Griff

    Griff Member

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    I should have been clearer - polyurethane. And I'll check out acrylic urethane paintguy. I'd never heard that there was such a critter. Thank you.

    Thanks to everyone for all the responses. I appreciate it.
     
  6. michaelprice83

    michaelprice83 Member

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    most "alive" guitar i ever had was a multi piece thick poly mexican fender jimmy v strat.
     
  7. CharlieNC

    CharlieNC Member

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    well, aside from the things already mentioned i prefer nitro because the finish actually ages. it doesn't remain a permanent piece of plastic like a polyurethane finish. overtime it will hardern and check, which to me, exudes a lovely patina you just can't get from other finishes.

    ymmv
     
  8. kovachian

    kovachian Member

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    Nitro will eventually crack and turn brittle and yellow. When this happens it seperates from the wood and allows the wood to breathe more freely and create a livelier tone. Strangely enough, it's nitro's worst flaw that becomes it's best asset.
     
  9. BrandonT

    BrandonT Member

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    Epoxy could be the trick, you can get a thick base coat, and after that use a nitro topcoat.
     
  10. paintguy

    paintguy Long Hair Hippy Freak Silver Supporting Member

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    When someome says poly I think polyester. When someone says polyurethane I think automotive and not the uncatalyzed type like mini wax or the ones that can be wiped or brushed on. That stuff is crap if you ask me. That being said, a catalyzed polyurethane would fall between acrylic urethane and polyester. I'm not a big fan of polyester. I find it to be real thick, super hard, not flexible at all, and very yellow. It's just too much like fiberglass resin or a super thick resin to me. Usually sprayed a 1/4" thick.

    A catalyzed polyurethane is basically a higher solids acrylic urethane.(at least in automotive clears). Not a bad product at all.

    The higher the solids, the thicker the material and the harder to buff. Hence my love for acrylic urethane. Has a thinness and breathes similar to nitro lacquer, but has better flexbility. Has the durability of a polyester or catalyzed polyurethane. Gloss is on the same level as any and buffing is quite nice, but not as easy as lacquer. Price is about 6x what nitro costs, and at least 2-3x of what polyester costs.

    Also, I find the any catalyzed finish to be much harder to work with than nitro, and really aren't for the DIY'er like nitro is.

    Enough said,

    Larry

    Btw, Jack, your last guitars and paint jobs have been killer!!!! Loving the bursts you do.
     
  11. Jack Briggs

    Jack Briggs Member

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  12. PB Wilson

    PB Wilson Member

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    I've heard and played great guitars with all sorts of finishes. I cringe when I hear someone say that one finish is lousy or the other is the best. Many of our most revered guitars were finished in nitro lacquer and that's what we seem to equate with quality. Unfortunately (or fortunately as kovachian stated) it continues to off gas and shrink, turn brittle and crack in time. On an old D-28 I think it looks fantastic, but on a relatively new guitar taken out in cold weather, it looks like crap.

    I think that a good finisher can use nearly any finish and make it work well. I think the real issue is repairability. Nitro and shellac can be repaired very well, but some of the more modern finishes make dings, scratches and dents look awful because the repair doesn't mesh with the original finish.

    Like anything in life, it's a tradeoff. Good thing we have luthiers trying out some alternative finishes because nitrocellulose lacquer is pretty dangerous stuff and not at all good for the environment.
     
  13. Mike9

    Mike9 Supporting Member

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    I like Nitro, but it's labor intensive - I'm shooting a Parker Nitefly in PPG urethane based RootBeer Pearl with clear coat. I like the time thing going with this. You have to be carefull layering lacquer and polyurethane. If you don't scuff coat it enough it can separate. I really hate thick finishes - they "choke" the wood IMO.
     
  14. Doug Allen

    Doug Allen Member

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    Some of the Clapton necks from the Fender Custom Shop have a coating of super glue. Reportedly, the necks on EC's personal guitars have that type finish. Why use s-glue, and, how is it applied?!
     
  15. EADGBE

    EADGBE Member

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    Wood doesn't need to breathe. As a matter of fact wood that lets air in out will evetually damage the wood. Fluctuations in humidity can cause cracks. I like polyurethane better because it protects wood better. My best sounding guitar is a Baretta and it has a polyurethane finish.
     
  16. LaXu

    LaXu Member

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    I still don't subscribe to the "nitro = better tone" thing. You see, my first guitar was this Chinese Ibanez strat copy that had (and I'm not lying) over a ½ cm thick finish of polywhatever. I mean REALLY thick. Yet that guitar had the loudest acoustic voice I've heard in a solid body and also looking back it did sound pretty good through an amp as well. Had the most massive neck that I've ever tried on a guitar, that might've had something to do with the tone.

    I do agree that thinner finishes LOOK better. Thick finishes give that "candy apple" look, like looking at wood through a thick glass.

    I think we can all agree that there are great guitars with various finishes. Some like nitro for it's aging factor but personally I'd rather have guitars that look almost new in 20 years.
     
  17. PB Wilson

    PB Wilson Member

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    I read about using superglue where it's spread out quickly rubbed with a soft cloth and once it's cured, given the once over with very fine sandpaper or steel wool.

    It must have a different feel and it should be quick and easy to fix if it ever wears through.
     
  18. PB Wilson

    PB Wilson Member

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    Thank you for saying that.
     
  19. Griff

    Griff Member

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    Thanks for all your responses guys.
     
  20. Soapbarstrat

    Soapbarstrat Senior Member

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    Probably because the neck would be done in less than 4 hours, and then no spray equipment to clean up. Finish is quite durable. More importantly, it would help use up super-glue before the bottle gets old enough where the label on the bottle becomes worn off, because what usually happens then, is the bottle of super-glue gets mistaken for a bottle of eye drops or hemorrhoid ointment.
     

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