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Thread: Sloppy Cyanoacrylate field repair. Now what?

  1. #1
    Join Date
    May 2019
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    112

    Default Sloppy Cyanoacrylate field repair. Now what?

    I am asking for suggestion on how to approach this repair. I got blase transporting my uke and packed it into my checked bag (well padded, I thought!). There was a change of planes along the way, and yes, the uke got damaged.

    Cyanoacrylate repair.jpgcloseup.jpg

    You can see in the pictures that a crack in the soundboard extends almost from top to bottom. Deep in a remote location, miraculously I managed to find some Cyanoacrylate, which I too liberally drizzled into the crack to save it from further injury. A few drops landed close to the soundhole as well.

    In the closeup you may be able to see another crack that is close to the top of the bridge, running to the bottom of the soundboard, as well as a harder to see small crack a bit below that.

    I can feel no interior damage. The braces seem tight to the soundboard.

    The wood is redwood, maybe 1.6mm thick.

    My main question is where to go from here? I am thinking the joint needs to sanded flat and more than likely, I shall have to refinish the top of the uke. Does this seem right? What grit would you start with?

    How should I deal with the 2 smaller cracks? Was I on the right track?

    I appreciate any pointers. Thanks!
    Last edited by eclipsme; 03-29-2020 at 11:23 AM. Reason: added pics

  2. #2

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    I would take a razor blade with a piece of scotch tape at each end of the blade and scrape off the excess glue before sanding. Sand with a small flat block. I would start with 120 grit and go up from there. Then refinish with whatever it was finished with after using a shelac under coat. I would do the same with the other cracks. You are going to see them, wabi sabi.
    Last edited by Michael Smith; 03-29-2020 at 12:58 PM.
    Michael Smith
    Goat Rock Ukulele
    www.goatrockukulele.com

  3. #3
    Join Date
    Oct 2014
    Location
    Little River, California
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    Do exactly what Michael says. But use a less viscous CA to fill other cracks.

  4. #4
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    May 2019
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    Quote Originally Posted by Michael Smith View Post
    I would take a razor blade with a piece of scotch tape at each end of the blade and scrape off the excess glue before sanding. Sand with a small flat block. I would start with 120 grit and go up from there. Then refinish with whatever it was finished with after using a shelac under coat. I would do the same with the other cracks. You are going to see them, wabi sabi.
    Thanks! The razor blade is a good idea!

  5. #5
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    May 2019
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    Quote Originally Posted by sequoia View Post
    Do exactly what Michael says. But use a less viscous CA to fill other cracks.
    How much glue is appropriate. As I was performing this repair, the glue absorbed into the joint, but I was concerned that it wouldn't hold so kept adding more. Would it have been enough to have stopped once the joint stopped absorbing? Thanks.

  6. #6

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    My experience using CA on a porous material, like a redwood top, is that it is not a once-and-done operation. The glue will continue to soak into the porous material as long as it is liquid, so it will seem like a lot of glue is being used. Much better to apply a little, which will soak in and seal the surface. Then a subsequent application will glue the area together since it will not longer soak in to the now sealed surface.

  7. #7
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    Stockton on Tees..North East UK.
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    If it was one I’d made I would have either given it away, or saved the bridge and neck and made and fitted a new top .....it’s like when your car has had a prang and been resprayed..it’s somehow never the same
    http://ukulele-innovation.tripod.com ebay i/d squarepeg_3000 Email timmsken@hotmail.com

    If you can believe that moving images and sound, can fly through empty space across the universe and be seen and heard on a box in your living room ?.. then you can believe in anything.

  8. #8
    Join Date
    Jun 2014
    Location
    Umeå, Sweden
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    I think it depends on if it is an emotional matter. A musical instrument is a very personal thing isnīt it?
    If you add too much CA it can be scraped and polished level, but if you donīt add enough strength structural issues might appear.
    Oftenly people that are carried by a passion for music might tend to be carried by that passion for their instrument too. So please donīt exaggerate.

  9. #9
    Join Date
    Jul 2009
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    UK
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    What's done is done, so far as the CA and that crack is concerned. Assuming the instrument still sounds nice, I'd cleat the underside of the crack to make sure it stays together, and then use a razor blade followed by very fine abrasive (P1000 and higher) and buffing compound to improve the appearance of the top as much as possible. It will still look pretty bad, but it's downright horrible now! With time it might acquire a quirky charm in your eyes as a memory of your trip.

    When using a razor blade go slow. You are gently scraping away the CA - resist any temptation to try to gouge off those lumps of CA, just keep scraping gently with the blade pretty much vertical until it eventually comes down to the level of the top.

    BTW I see what looks like another crack, running from the tail to nearly the corner of the bridge. If it is a crack, that should be fixed properly with hot hide glue or Titebond Original and a couple of cleats.

  10. #10
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    May 2019
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    Quote Originally Posted by Michael Smith View Post
    I would take a razor blade with a piece of scotch tape at each end of the blade and scrape off the excess glue before sanding. Sand with a small flat block. I would start with 120 grit and go up from there. Then refinish with whatever it was finished with after using a shelac under coat. I would do the same with the other cracks. You are going to see them, wabi sabi.
    So far so good. The razor got most of the excess off. Now I have to order some thinner glue. Thanks for the pointer. BTW - I do not currently have any shelac but am considering spotting the bare spots with poly. Comments?

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