Nitro finish repair??

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by AceBSpankin, Apr 21, 2015.

  1. AceBSpankin

    AceBSpankin Prince of Ales Gold Supporting Member Supporting Member

    Messages:
    3,613
    Joined:
    Nov 10, 2009
    Location:
    Dakota Territory
    I have been building a Martin style 14 fret Dred, Spruce top, Indian Rosewood sides and back.
    Was turning out relatively well for a first attempt.

    I have the finishing all done and laid out the bridge to be glued on.
    I use some masking tape under the bridge for lay out purposes.

    Long story short I laid it out for 24.9 instead of 25.4 and scored around the bridge thru the tape and the finish.

    So......when I moved it back to the correct placement I'm left with a 3-sidded score line in the Nitro finish.

    Is their a technique for blending this?
    I wont refinish the whole top, so I'm looking for suggestions on the best cover up!!!!!
    Please and Thank You,
    Neal
     
  2. bunny

    bunny Member

    Messages:
    443
    Joined:
    Nov 19, 2007
    Sand the top finsh smooth, make sure there's no polish left at the area.
    Drop fill the score line with the same nitro lacquer (I'd use a #1 artist's brush), let it dry, repeat, etc until you have a very little ridge where the indentation was. Sand it flat (a razor blade scraper works great on nitro, then comes the sanding block). Polish.
    if you used a rattle can finish, you may mask the guitar leaving just a narrow strip exposed around the line and carefully spray it over.

    You may not be able to get rid of the trace completely if the line across the grain is deep, but nitro tends to blend well, especially while it's still relatively fresh. In some cases you may spray the whole top over after filling the dents/scratches and sanding the spots flat.
     
  3. poolshark

    poolshark Supporting Member

    Messages:
    2,982
    Joined:
    Sep 1, 2007
    Location:
    Flahrida
    I like the idea of carefully painting the score lines with a brush, masking the 'good' parts of the top, then hitting the repair area with some blush eraser to burn the repair in. Wet sand, polish, done.
     
  4. AceBSpankin

    AceBSpankin Prince of Ales Gold Supporting Member Supporting Member

    Messages:
    3,613
    Joined:
    Nov 10, 2009
    Location:
    Dakota Territory
    Thanks for the ideas/tips guys!!
    I did a 1&1/2 pound cut of Shellac, French polish style till I got the deep amber color I wanted.
    Then shot 1 whole can of StewMac. clear Nitro over the top.
    So........I'm out of rattle can Nitro, can I use some brushing Lacquer that I have on hand??

    Thanks,
    Neal
     
  5. bunny

    bunny Member

    Messages:
    443
    Joined:
    Nov 19, 2007
    Nitro over FP? I use shellac as a sealer from time to time, but never more than that under nitro...
    To cure scratches on (in?) nitro you normally use nitro, and nitro varies a lot, different formula, viscosity, tint, so I'd try to use exactly the same product as the existing finish.
    It's ok to use something filling gaps at the bindings etc, but since you have a scratch line across the grain at a quite visible area, and the guitar is new, it'd be frustrating to see it after all :)
     

Share This Page