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Thread: Question about CA glue

  1. #1
    mandolin slinger Steve Ostrander's Avatar
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    Default Question about CA glue

    I recently bought a used mando that has a small pickup disk glue to the top near the bridge. It appears to be CA glued. Itís not putty, I know that much. Is there any way to remove the disk? Will acetone solvent damage the nitro finish? Or should I just live with it?

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    Default Re: Question about CA glue

    Acetone will definitely damage the nitro. And that’s the only thing I can think of that will release CA. There is no way to remove that without causing some damage. I’d say live with it. Or if you must remove it, maybe you could physically break the bond by working something like a thin piece of plastic under it. You would likely remove some finish but that could be repaired. Any damage that would occur would not be as bad as the potential damage from using solvent, which has a nasty habit of going where you don’t want it.
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    Registered User Greg Mirken's Avatar
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    Default Re: Question about CA glue

    What brand mandolin? If it has a poly finish you can use solvents that eat nitrocellulose lacquer.
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  4. #4

    Default Re: Question about CA glue

    You could glue a pearl disk on it and call it a beauty mark. Howsomoever, most common CA loses strength below 200F, so a carefully controllled heating might do the least finish damage, but you’d have no idea what the finish underneath looks like right now - it could be very much compromised already.

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    Registered User sunburst's Avatar
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    Default Re: Question about CA glue

    If it is a nitrocellulose lacquer finish and if it is glued with CA the damage was done as soon as the CA hit the surface.
    If, as Greg said, it is a poly finish you are in luck, but it is still not an easy removal most likely.

  6. #6
    mandolin slinger Steve Ostrander's Avatar
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    Default Re: Question about CA glue

    Quote Originally Posted by Greg Mirken View Post
    What brand mandolin? If it has a poly finish you can use solvents that eat nitrocellulose lacquer.
    Kentucky km500.

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    Registered User poul hansen's Avatar
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    Default Re: Question about CA glue

    You could use a Dremel sander and carefully sand the PU away, down to the finish and with any luck the finish can be polished up.

    If you break it off, you risk that flakes of the finish follows it or even some of the wood.

    I once removed a PU that was stuck on with doublesided tape and it took all the lacquer with it.
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    Registered User Greg Mirken's Avatar
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    Default Re: Question about CA glue

    The current KM500 claims to be nitrocellulose; older ones might have a synthetic catalyzed finish. The only way to tell for sure is to test an area with acetone. I pull off one side of tuners and swab a small spot with a Q-Tip where it will be hidden. If the acetone doesn't mark the finish at all you're in business.
    You'll have to slowly wick acetone around the perimeter of the pickup element until it slowly penetrates. It will take a while.
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  10. #9
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    Default Re: Question about CA glue

    CA has a way of sticking really well when you don't want it to, and not sticking when you do want it to stick.

    Acetone eats nitro. So does anything else I know of that weakens super glue. I suppose you could try some rubbing alcohol, but . . . I would be wary of even using that.

    If you've got a variable temperature controlled soldering iron, you might try to set it at the lowest heat and see if that will take it off before it burns the finish too badly. You can try to start a thin piece of metal or razor blade between the pickup and the top, and with some luck, you might be able to wedge it off before you get too much damage. If you don't have a temp controller for your soldering iron, a router speed controller might work in a pinch.

    I think that no matter what you do, you're going to have some finish damage. The best you can hope for is to keep the damaged area as small as possible.

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    Registered User Tom Haywood's Avatar
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    Default Re: Question about CA glue

    Photo?
    Tom

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    Default Re: Question about CA glue

    About 2AM, this got me thinking, which is a bad thing. If the OP has some electronic background, the piezo could be connected up and driven, possibly enough to disrupt the usually brittle CA. Any frequency in mid audio would be good, and as these things can take fairly high voltage, run it up till it can be heard clearly.

    On the thermal softening technique, a substantial iron rod, like a big nail, in boiling water would be a guarantee of proper temperature and good conductivity.
    On temp controls: if no separate router speed control, any SCR lamp dimmer, like one from a wall switch, is plenty good enough for many purposes under a kW or so. Heaters, speed control (universal motors only), input to simple power supplies.
    On getting back to sleep - no advice at all.

  13. #12
    Registered User Tom Haywood's Avatar
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    Default Re: Question about CA glue

    CA is notorious for breaking with a sharp blow. If the finish is going to be damaged anyway, it might be reduced by just breaking it off. Without a picture, this is blind advice.
    Tom

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    Default Re: Question about CA glue

    I have pried off pickups glued with CA, saving the pickup. Tho this was on bare wood, but it is still a possibility on a finished surface, especially if that surface has been damaged by the CA. I used a violin soundpost setter and ground the wide part sharp to pry under the pickup. A similar tool can easily be made. Patience/slow is the key here.
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    mandolin slinger Steve Ostrander's Avatar
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    Default Re: Question about CA glue

    I was able to slice it off with a razor blade with minimal damage to the finish. Thanks to all who posted advice.
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    Default Re: Question about CA glue

    Glad it worked out for you. Risky move with good outcome. You probably were going to have damage no matter what you did. If the minimal damage is a chip of missing finish it can probably be drop-filled.
    Don

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