Removing wood glue from a previous repair

Construction and repair of Classical Guitar and related instruments

Removing wood glue from a previous repair

Postby chef » Thu Jul 08, 2010 6:01 pm

Hi all,

I received a guitar with a cracked top about a year ago and I decided to repair it myself. I used wood glue to glue the cracked portion of the top but I did not clamp the crack together while it is drying so even though the crack is sealed, it is not even.

I am wondering if I can do this over? How can I remove the wood glue from my previous repair so I can re-apply the wood glue and clamp it together this time.

Thanks!

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Re: Removing wood glue from a previous repair

Postby Steve Ganz » Thu Jul 08, 2010 6:35 pm

Talk about the crack or post a picture.
Where is it?
Is it straight?
How long is it?
What "wood glue" did you use?
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Re: Removing wood glue from a previous repair

Postby Waddy Thomson » Thu Jul 08, 2010 7:06 pm

What glue you used is important. Some glues do not stick well to themselves, while they stick fine to raw wood. The problem with cleaning a repair like this is getting the old glue out of the crack. If you used hide glue or fish glue, you can always re-glue, if you can get it apart again. Titebond and such are more problematic in a situation like this, as you have to remove the old glue - hard to do without making the crack bigger, though some folks have used De-Glue Goo with some decent results removing Titebond and similar glues.
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Re: Removing wood glue from a previous repair

Postby Robert England » Thu Jul 08, 2010 8:09 pm

Waddy, what is "De-Glue Goo"? That sounds vey useful to have on hand.
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Re: Removing wood glue from a previous repair

Postby chef » Thu Jul 08, 2010 8:14 pm

I used Elmer's wood glue. I don't know if that was the right glue to use, I just did not want to use super glue since it is easier to clean up after wood gle than super glue. The crack is straight, about 4 inches from the bottom part of the guitar. I'll take a picture when I get the chance.
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Re: Removing wood glue from a previous repair

Postby Waddy Thomson » Fri Jul 09, 2010 2:52 pm

De Glue Goo, is a gel product, available at wood working stores, that is designed to put on surface glue, and remove it. You have to spread it on and let it sit, but it dissolves PVA glues readily, and as I understand it also works on Fish glue and HHG. It's mostly vinegar in a gel, and vinegar will dissolve it too, but it dries before it gets the work done, unless you wet a rag in it and put that on the glue. It will work fine for Elmers', but I don't know how you'd get the glue out of the crack after it is softened, without damaging the crack more. Elmers' like other PVA glues will not stick to itself, so if you want to re-glue it, you'll have to remove it. It's one reason to always check with a builder or repair person before doing something like that. If you don't have HHG, you can always buy a bit of Knox gelatin at the grocery, put it in a glass, with an equal amount of water, heat it, in some water, to 140*, stir it till its liquid, and, voila, hot hide glue! Use that for crack repairs, and they can always be re-glued without much in the way of clean up.
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Re: Removing wood glue from a previous repair

Postby David LaPlante » Sat Jul 10, 2010 1:18 am

I like the use of a steam needle to soften and or dissolve old glue. This is made using a Mr. Coffee expresso maker (or some other steam source) and a tube with a sports ball air fill needle attached. This device is used for steaming out dovetail necks in the SS world.The needle allows you to apply concentrated heat and moisture right on the glue and usually does the trick. You do have to be careful with your fingers as well as not getting too much moisture on the parts of the guitar that you <want> to stay together.
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Re: Removing wood glue from a previous repair

Postby jim 16 » Tue Jul 20, 2010 9:20 am

Cleanup of carpenters glue , to re-do a repair ; use a lot of patience , soft or medium brush , q- tips etc and keep the surface dry as possible , don't damage the wood fibers . Patience .
Hide glue has an advantage in that it is transparent , tough , can be cleaned up readily , and is malleable ,
re-workable . If it is desired that it be removed , warm water or a bit of steam will do that easier than with other glues . Vinegar will destroy the glue and make it easily removeable ; I even took piano parts apart that way in some cases when I was afraid of ripping grain or other breakage . A little bit of baking soda dissolved to equalize the acidity
, and then rinse in clear water .
Cracks that were closed , I used to put a sympatheic string from sitar , like a tiny drill , through the crack and then sew
the cleat with glue on the inside , the string going through a small block of wood with a violin peg acting as a clamp .
But if a crack will level , noedymium magnets of the right strength and size can be very handy , as a clamping method .One must be carefull of denting wood as the things can slam together .
One on the outside , and one on the inside with a wet cloth tied around it , can clean up glue , or abrasive attached
to the inside magnet offers a sanding method where hands cannot go .
If using cyanoacrilate glue ; paint vaseline where you do not wish the glue , either side of the crack and surrounding area , and be thorough . ( Works on nails too if you build nails like the flamencos with cyano ) Pretest for glue flow
, use a thin tip applicator , and apply not more than you need . Acetone will dissolve and remove it .
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