Separated finish

If you have a string instrument of any kind that needs fixing, a mistake you made in building a new instrument that you need to "disappear," or a question about the ethics of altering an older instrument, ask here. Please note that it will be much easier for us to help you decide on the best repair method if you post some pictures of the problem.
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Henrique Schneiter
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Joined: Sun Feb 05, 2012 12:59 am

Separated finish

Post by Henrique Schneiter »

Hello guys. In the process of sanding/polishing the finish, this guitar took a bump and some of the finish (PU) cracked and became separated from the top. As it's hardwood top and binding, there is no dent, and the crack itself is barely visible and not palpable, then my first idea to simply inject some CA glue on the crack seems unplausible.

Any ideas are welcome.

Henrique Schneiter
Posts: 98
Joined: Sun Feb 05, 2012 12:59 am

Re: Separated finish

Post by Henrique Schneiter »

Here's the picture.

Henrique Schneiter
Posts: 98
Joined: Sun Feb 05, 2012 12:59 am

Re: Separated finish

Post by Henrique Schneiter »

Screenshot_20210407-213013_Gallery.jpg

Mark McLean
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Re: Separated finish

Post by Mark McLean »

If it is not through the full thickness of the finish - and given that it is such a small area - you would probably get away with just sanding and buffing it out. Watch this video by Dan Erlewine to learn the strip sanding technique (at the end of the video).
https://www.stewmac.com/video-and-ideas ... inish.html
If you think it is through the full thickness of the finish then you will need to drop fill. You could use CA glue or PU (if you know that to be the finish - but it is more likely to leave some witness lines).
cheers
mm

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Barry Daniels
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Re: Separated finish

Post by Barry Daniels »

I would definitely try some water thin CA glue. It might seep in and make it disappear. Not much to lose trying this. When you put the CA on, if it does not seep in all the way, wipe off the surface then press on the area with your finger to try to pump the CA a bit more.
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Henrique Schneiter
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Joined: Sun Feb 05, 2012 12:59 am

Re: Separated finish

Post by Henrique Schneiter »

Mark, it's not a chip, but more like an Air bubble under the finish. The surface of the finish feels intact. Anyways there's good advice on the vídeo.

Barry, I'll try to inject some CA with a needle and a syringe.

I might skip the wood sealer on the next PU finish...

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Barry Daniels
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Re: Separated finish

Post by Barry Daniels »

You don't want to inject the CA. That could lead to it squirting everywhere. Place small drops on the open fracture and let it seep in. Try not to get glue on the entire length of the fracture as that will seal it off and prevent the air from escaping, which it must do in order to allow the CA to penetrate fully.
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Henrique Schneiter
Posts: 98
Joined: Sun Feb 05, 2012 12:59 am

Re: Separated finish

Post by Henrique Schneiter »

Barry, I've followed your advice and it worked nicely. Thank you again.
Screenshot_20210414-225723_Gallery.jpg

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Barry Daniels
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Location: The Woodlands, Texas

Re: Separated finish

Post by Barry Daniels »

Nice.
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