Official Luthiers Forum!

Owner of this guitar bought one of mine. He accidentally sat on the Gibson years ago. Local repair shop fixed the cracked diagonal braces by glueing and compressing. No caps. The cracks were glued somehow, no internal bracing for them. Painted again and shot with Nitro. The cracks are back. But braces look good (endoscope). What would u do to fix cracks and make them dissappear? Should I put caps on the repaired braces? I’m thinking a refinish when done.

My 2 cents. I'd leave the cracks alone visually. I'd make sure they're cleated where they need to be moreso than anything else.

My guess: There's nothing OP could do, or commission to do, externally, that wouldn't devalue the instrument. Professionally installed internal cleats, sure. Anything external, enjoy the history.

_________________
Peter Havriluk

For cleating cracks, I think Thompson's method is gaining traction. Barry Daniels can fill you in on the details:

https://www.mimf.com//phpbb/viewtopic.php?f=8&t=6381

Overspraying and refinishing old instruments isn't as popular as it once was.

I thought I provided enough information to avoid the discussions above. The guitar has already been devalued with a repaint and a refinish. Not sure how much more I could devalue it. Second, the owner wants it. Trust me, the owner knows guitars. He already chose to devalue it with previous repair.

So, let’s put that behind us. I’m looking for advice on closing the cracks. Cleating is a given.

Humidify, humidify, humidify to close cracks.

_________________
Remember, there are no stupid questions, only stupid answers!

If the wood has dried out you may have to splint some of the larger cracks. Humidification may close them but they may not stay that way when the wood comes back to normal humidification levels.

The cracks are fine to very fine. I may have to by the air glue gun that stew mac sells. Should I pressure the glue in then humidiy?

You need to close the crack first. It may take a few days to humidify the guitar and get the cracks closed.
Put the guitar in a large clear plastic bag along with a couple of water saturated sponges, don’t let the sponges touch the instrument, you may want to put the sponges in a container with holes in it to keep them from touching the guitar.
I usually just wrap the opening of the bag around the neck and hang it up. Check it regularly and when the cracks look to be closed take it out and rub some hhg into the cracks sometimes it helps to run a bead of distilled water along the crack followed by a bead of hhg, then force the glue into the crack by rubbing across the crack with your finger and apply a bit of pressure along the crack with your other hand. The glue will wick through the crack.
Clean the glue up, apply the cleats, and you should be good.
Alternately because the guitar will receive a new finish you could probably just humidify to close them and then wick some CA glue into the cracks and cleat.
It’s your call really. With a refin I would look at using the CA rather than the hhg I think, but it’s not my repair and I’m only giving you a couple of options.

_________________
Remember, there are no stupid questions, only stupid answers!

Cal, you don't worry about CA staining the spruce? Or is that an end grain problem only?

It’s an endgrain issue. I’ve never experienced staining when I’ve used it to glue cracks. If you like you could do a test on scrap. It’s a good idea to test anything that you haven’t tried before. I will test if I haven’t tried something so I don’t get a surprise result on a customers instrument. This goes for most anything.

_________________
Remember, there are no stupid questions, only stupid answers!

I've also never had a problem with CA on cracks although I normally use HHG. If there is any crushing or end grain involved then a bit of shellac goes on first.

_________________
Steve Smith
"Music is what feelings sound like"