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Repairing hairline crack in poly finish

Discussion in 'Finely Finished' started by andrewnelles, Sep 30, 2017.

  1. andrewnelles

    andrewnelles Tele-Meister

    Age:
    30
    167
    Jul 11, 2003
    Chicago, IL
    I got a killer deal at a local shop on a brand new Epiphone Casino with seemingly minor shipping damage.

    The neck has a hairline crack coming from the nut that appears to be only in the finish, see photo. The head-stock seems stable, and it was perfectly in tune when I got it home, so I'm optimistic the wood is intact. Plays great. Will pop the strings off tomorrow and hive the head-stock a good wiggle to confirm.

    I am hoping to conceal the crack, or at least smooth it out. What is the best approach for repairing poly finishes?

    I was thinking about covering the crack with some Black Tint StewMac Super Glue, and then sanding and buffing. Would this be an appropriate approach?

    Figured for $270 price tag, picking up this guitar would be a fun project.

    Thanks in advance.

    crack.jpg
     

  2. W.L.Weller

    W.L.Weller Tele-Meister

    208
    May 20, 2014
    Queens

  3. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    Very, very difficult. First it's a matter of tinting the bare area, then it's fixing the finish. Black wood dye with an ultrafine artist brush and magnifier would be the best way to get color in there. Finish repairs are generally done by drop-filling with thin cyanoacrylate followed by scraping with a blade edge used like a cabinet scraper.

    But honestly that does not look like a finish crack. Neither the color nor pattern makes sense for a finish-only issue, especially with polyurethane. When you say it's stable, how much force have you actually put on it? IFf it's only a finish crack you can seriously lean into it and it'll hold, and you will be unable to slip a pin into it. But if you can it's NOT a finish crack and needs to be properly repaired.
     

  4. Jupiter

    Jupiter Telefied Ad Free Member

    Jun 22, 2010
    Osaka, Japan
    Yeah man, that is a really suspicious crack...
     
    Dismalhead and rich815 like this.

  5. andrewnelles

    andrewnelles Tele-Meister

    Age:
    30
    167
    Jul 11, 2003
    Chicago, IL
    When I de-string it tomorrow, I'll really give it a really good push and see if there is even slight movement.
     

  6. andrewnelles

    andrewnelles Tele-Meister

    Age:
    30
    167
    Jul 11, 2003
    Chicago, IL
    Curiosity got the best of me, just de-stringed it. With extremely heavy pressure, the crack does open a tiny bit. Thickness of a sheet of paper I'd say.

    Looks like I'll be pursuing a headstock repair project instead then. Going to be tough to get glue in there without forcing the crack to grow. Time for more research....
     

  7. harold h

    harold h Tele-Afflicted

    Feb 15, 2004

    If that is the case, about the only way to repair without major
    surgery will be to wick water-thin super glue into the crack.

    You can then use a razor blade to remove the excess before any
    sanding or buffing.

    And dont worry, Gary Rossingtons main Les Pauls headstock was
    repaired with superglue in the 70's when it fell and broke.

    Last I heard a few years ago the repair was still intact.
     

  8. andrewnelles

    andrewnelles Tele-Meister

    Age:
    30
    167
    Jul 11, 2003
    Chicago, IL
    Couldn't sleep, so I got to work.

    This thing sure is strong... I built a little temporary jig and used some clamps to get the crack open just a hair more. Took a lot of force to get it to open up even slightly.

    Used a syringe to inject some slightly thinned Titebond. After a few attempts it appears to have reached about 70% down through the crack. That's where the oozing out stopped. Couldn't get it all the way down to the last 1/4" or so, guessing maybe the wood hadn't actually split that far.

    Between the glue, and the fact that string tension is working in favor of keeping the crack closed, I'm feeling confident this will be stable.

    Guitar is clamped and drying for 24hrs.

    Then back to the finish...
     
    DonM likes this.

  9. Jupiter

    Jupiter Telefied Ad Free Member

    Jun 22, 2010
    Osaka, Japan
    I bet that works. ;)
     

  10. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    A definite headstock repair.

    Oh, sorry -I wish I'd caught you ahead of that.

    On this type - almost any type - of DIY neck repair only hide glue should be used. There is one made by Titebond that is close to hot hide glue. It has a shelf life, but is good stuff for DIY repairs.

    It's removable in case the repair doesn't hold well and needs to be redone. But regular Titebod, cyanoacrylates (which should NEVER be used for a structural repair), acrylics, vinyls etc all create one-way repairs. If the joint spreads at all you can't reglue it - you have to break it apart, dowel the neck with added splines etc etc...not DIY work.
     

  11. robt57

    robt57 Telefied Ad Free Member

    Feb 29, 2004
    Portland, OR
    I am not thinking so either.
     

  12. W.L.Weller

    W.L.Weller Tele-Meister

    208
    May 20, 2014
    Queens

    Not to disagree with your approach, and realizing that I may have weakened my credibility by posting a "joke" tip first, but Frank Ford, a devoted hot hide glue user, uses Titebond on the similar repair in this link.

    http://frets.com/FretsPages/Luthier/Technique/Structural/BrokenHeadstocks/NeckCrack/neckcrack.html

    The string tension won't allow that crack to open up if subjected to the inside of a hot car.
     

  13. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    Please re-read my post. I said "DIY" repairs. I use all sorts of adhesives, but I've done countless neck break repairs. Self-repairs of neck and headstock breaks commonly re-break, hence the "re-repairable" joint.

    I can't comment on the use of "Elmer's Interior Carepenter Wood Glue". I don't know any techs that use it. No idea if it's equal to Titebond or Titebond II.
     

  14. andrewnelles

    andrewnelles Tele-Meister

    Age:
    30
    167
    Jul 11, 2003
    Chicago, IL
    Thanks for all the good feedback and discussion guys.

    Just removed the clamps and gave it a once over, all seems well. No flex in the crack whatsoever, even with some pretty extreme force applied to it. The gluing seems very solid.

    No back to the finish. The crack is nearly invisible, there is no void in the finish. However there is just the slightest ridge created. I don't notice it while playing honestly, but I know it's there.

    To help smooth and seal it, I'm thinking a thin line of black tint CA over the length of the crack, scrape with a razor, then smooth with some fine micromesh, and buff. Is this a bad approach, or worth a try?

    I'm enjoying this learning experience so far.
     

  15. Jupiter

    Jupiter Telefied Ad Free Member

    Jun 22, 2010
    Osaka, Japan
    That's pretty much how I think I'd do it, except I don't have black CA (and don't know how I'd find it in Japan), so I'd probably use epoxy or something.
     

  16. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    If it's a ridge - one side higher than the other - than no, it's nearly impossible to create a relatively seamless "ramp" using glue in a thin bead like that. I suggest using a razor blade with the edge "turned" like a cabinet scraper and lowering the high edge. Even if you go a hair deep you can come back with a black lacquer touch-up pean (Stewmac sells them; Mohawk also has dozens of toner and opaque colors).
     

  17. Old Tele man

    Old Tele man Tele-Afflicted

    May 10, 2017
    Tucson, AZ
    When a crack opens up in the cement under your feet, you really gotta wonder if there's a bigger crack in the earth down below too!!!!
     
    Last edited: Oct 1, 2017

  18. andrewnelles

    andrewnelles Tele-Meister

    Age:
    30
    167
    Jul 11, 2003
    Chicago, IL
    Makes sense to me, thanks!
     

  19. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    Please let me know how it works out.
     

  20. Vizcaster

    Vizcaster Friend of Leo's

    Sep 15, 2007
    Glen Head, NY
    Building up black CA on the ridge and trying to feather that out will result in a pretty wide strip of repaired area. Might be counter-intuitive but I'd try scraping the ridge with a razor blade or utility knife to make it less noticeable and level first, then fill in and buff it out.
     

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