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thicker finishes more prone to stress cracks?

Discussion in 'Luthier's Corner' started by Bass-only, Jul 19, 2007.


  1. Bass-only

    Bass-only Supporting Member

    Oct 9, 2001
    Cleveland
    Greetings all.

    I have a G&L L-2000 in a silver sparkle finish. To get all those "sparkles" in there and then a clear coat, I assume this is a "thicker" finish than typical?

    Reason I ask is that my silver sparkle has a small stress crack on each side of the neck pocket. I did pop the neck and it doesn't appear to be in the wood (although it's hard to tell because they are in the corners of the pocket. On one side the crack is approx 1" long and on the other, maybe a 1/4". Either crack seems to be separating or growing, so I am assuming it to be a "finish" crack.

    Any input / comments would be appreciated.

    Thanks!

    Bob
     
  2. I would say it has to do with how brittle or elastic the finish is once cured rather than it's thickness. Wood moves constantly with temperature and humidity changes, so a brittle finish will crack if the wood moves enough.
     
  3. I agree, it probably depends more on the type of lacquer. Nitrocellulose lacquer tends to "breathe" and move with the wood more readily than some other kinds of lacquer.
     
  4. Bass-only

    Bass-only Supporting Member

    Oct 9, 2001
    Cleveland
    Thanks, guys.

    Given it's not a lacquer finish, it sounds like it's a result of either a lot of wood expansion / contraction or cranking the neck screws too tight?

    Is that a common "crack point" coming right out of the corner of the neck pocket?
     
  5. Oh... well what kind of finish is it then?

    So these cracks are on the side walls of your neck pocket? That's not too surprising, especially if it was a very tight fit from the factory, then the wood started moving, expanding in a lot of humidity.
     
  6. Angus

    Angus Supporting Member

    Apr 16, 2000
    Palo Alto, CA
    Although the elasticity is very important, it is true that thicker finishes (versus a thinner finish of the same material) will be more likely to crack as the bending stresses are directly related to the thickness, so they will be higher on the outer surface as the finish gets taller. I would say the material would be the dominant factor still, though.
     

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