Poly vs Nitro: what's the difference?

Discussion in 'Luthier's Corner: Guitar & Bass Technical Discussi' started by GibsonSGgirl, May 30, 2007.

  1. GibsonSGgirl

    GibsonSGgirl Silver Supporting Member

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    My main question is what's the difference between poly finish and nitro? Which strats have which finishes? And what's this 'thin skin' strat I've heard about? Any good?

    How can I tell if my Strat has a poly or nitro finish? It's a AV 62 RI made in 1996. Is the back of the neck a nitro finish? I'm assuming it is since it's shiny/glossy and not satin.

    Also, how can I tell if it's an alder or ash body? Is there a definitive guide anywhere that lists what materials Fender used during which years? It's on the lighter side for a strat, I think it weighs around 7 lbs or so but I have no scale to verify that.

    Cheers,
    Katie
     
  2. paintguy

    paintguy Long Hair Hippy Freak Silver Supporting Member

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    Katie, do a search here on this subject. There have been a ton of threads and responses. Enough to make some of us a little tired of this subject or debate. Not trying to dis you. It's just been covered so many times.

    Good luck!
     
  3. Jason417

    Jason417 Silver Supporting Member

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    I'll help, Katie.

    Poly finishes are essentially a thin layer of clear plastic. You can imagine the negative effect a thick layer of plastic could have on wood if done incorrectly! The positive side is, the poly is extremely strong, difficult to crack, easily buffed free of scratches, and is more transparent to light. Poly finishes do not age, get sticky, or turn to dust. Cheap guitars will have one thick shot of poly, like a candy coat (Estaban). You can tell a bad poly finish from about 20 feet because it will be runny looking (like an old pane of glass). A good poly finish is less than .002" thick (PRS) and has no negative effect on the sound. .002" is six times thinner than the high "E" on your acoustic. Anyone who can "hear" this is in my opinion fooling themselves.

    Lacquer is more or less organic in composition (cellulose) and is quite porous. It is hard to shoot without becoming 1) sticky or 2) cracked and checked. The Lacquer honks and old fashioned codgers will tell you that lacquer sounds better, but it can be applied incorrectly, too. Lacquer is easily checked, cracks with weather/humidity/temp changes. It can become sticky, it can turn to dust and fall off after 50+ years. Lacquer does age with the wood, which is good if you want an old looking guitar.

    The dirty secret of most lacquer guitars is the lacquer is applied on top of a base coat of wood sealer, usually made from Poly! So that Lacquer finished Stratocaster that the store owner will tell you sounds like the business actually has a polyester wood sealer on it under the lacquer! Even 50s strats had a wood sealer.

    The "Thin Skin" guitars don't have the undercoat. This sounds like a good idea until you go about three winters with the guitar and the finish starts to sink into the grain and look worn out.

    So here's the thing: Poly is the smarter choice because of the durability, Lacquer is the better choice because there are piles of guitarists who will pay more for it (because they were told Lacquer is better).

    In summary, Lacquer will look cool and beat up, Poly will look shiny and new longer.

    If you want to see a good example of a great poly finish, look at Taylor, PRS, and Gretsch. If you want to see a bad example, look at any Carlo Robelli or house brand $50 guitar. A great Lacquer finish would be on a Martin or CS Fender, a bad Lacquer would be on any used Gibson from the 70s-90s.

    Your AVRI is a lacquer finish, most likely with a Poly wood filler layer underneath.

    Cool?
     
  4. K-Line

    K-Line Gold Supporting Member

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    Most likely has some sort of poly underneath. Not like the imports or even the am standard stuff. A bit of urethane is ok if used sparingly. I have built bothways, ABed them and no way to hear a difference because the finishes were as thin as possible. If DIY, use shellac after grainfilling. A nice uniform coat of Zinnser's BIN will not allow the laquer to penetrate and eat into the grain and raise it up. I am lucky that when I shoot, I want all that look so I just use sanding sealer to build the wood up a bit before spraying.
     

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