Crack Repair Failed on Gibson A

[RayMan7]

Well I`m pretty heart broken on this one. I bought this mandolin a few months ago as a project knowing I would need to fix the crack, which really did come out perfect and I thought I did everything right. I played it the whole summer with no problems, but when I just took it out of the case my heart dropped, the crack is completely open.
I have no idea how it happened, I used Titebond original and cleated the crack underneath and reglued the brace, I thought that would be solid enough. Its been a pretty hot and dry summer here but this last week has gotten alot colder with a bit of rain, could that of done it?

I have no idea what to do now, so Im asking for any advice from those who really do know what you`re doing.

(first 2 pics are of the repair afterwards, which brought the arch back, and last 2 pics I just took)

[sunburst]

What to do now?
Get the strings off, first of all.
There is a lot of sheer force on a crack along side the fingerboard. Cracks there are fairly common in guitars and mandolins. Titebond does not resist a constant sheer load as well as hide glue and can creep and eventually fail (though a shock sheer can pop hide glue loose while Titebond might hold up). I would have glued that with hide glue and it might have held up, but if it didn't, it could be re-glued without having to clean all the old glue out of the crack. At this point, all the old Titebond has to be cleaned out of there in order to get a good glue joint. Unfortunately, there is no good way to do that without removing the top from the mandolin, and that is such a big job, I think I'd wait and see if anyone reports success with using vinegar of a stronger acetic acid solution to wash Titebond out of a crack like that. If it can be cleaned and re-aligned, then it's time to figure out how to glue it again, so first things first.

[Tavy]

I'd go nuclear and turn the crack into a slot (so you get good clean gluing surfaces), insert new wood, reinforce like heck from behind too, then touch up as best you can: that's the hardest part! Hopefully others will have less invasive ideas...

[Jeff Mando]

After it is repaired, pretty or not, hunt down a vintage pickguard and it should cover 100 percent of the damage. Out of sight, out of mind.

[pfox14]

Two great responses. The crack wants to stay open so filling it is the best idea, plus covering it with a pickguard will do the job nicely.

[RayMan7]

Thanks guys, that was the same thought I had when I woke up this morning. And dont worry, I loosened all the strings within 10 seconds of seeing the crack! The part I was most afraid of is getting all the old glue out, especially because the crack is at an angle and switches to a few different grain lines. But it would be alot easier to clean out if I use a spruce strip.
I actually remember when I first glued the crack it was extremely hard to get it together, I even thought about adding spruce strips because the crack just wanted to stay open. I do have the pickguard so thats good.
Dont leave your mandolin in the car! Yesterday was the only day I left it in the car, I think it got too hot in the case so I believe thats how it happened :/

[Bill Snyder]

Dont leave your mandolin in the car! Yesterday was the only day I left it in the car, I think it got too hot in the case so I believe thats how it happened :/

I think you probably have your answer to why your repair failed.

[RayMan7]

I think you probably have your answer to why your repair failed.

Yes, I honestly completely forgot I left the house with it yesterday. It was a big mistake, but now I just need to figure out how to get it playing again. Though I remember about 2 days before the top looked more sunken than usual, so it was already starting to fail when it happened.

[Marty Jacobson]

Yeah, a V-shaped splint w/ additional cross-grain reinforcement underneath seems like the way to go with this. This is a seam that wouldn't go back together which I repaired with a V-shaped splint. The cool thing is that you can put hide glue on the splint and then tap it in lightly. It's kind of self-clamping and shows zero glue line. The key is to get the wedge splint the same shape as the groove. I use a reciprocating chisel Stew-Mac used to sell that's wedge-shaped, makes it very easy.

[sunburst]

Yesterday was the only day I left it in the car, I think it got too hot in the case so I believe thats how it happened :/

Yep, once is all it takes, especially with Titebond (or other AR glue).
Looks like I'm in the minority here in thinking a splint should be a last resort. Hopefully, the old glue can be cleaned out and the crack re-aligned.

[RayMan7]

Yep, once is all it takes, especially with Titebond (or other AR glue).
Looks like I'm in the minority here in thinking a splint should be a last resort. Hopefully, the old glue can be cleaned out and the crack re-aligned.

A splint was going to be my last resort, but the mandolin pretty much sat in its case cracked with string tension for about 40 years, so the shape of the top has changed and causes the crack to stay open. When I first clamped it together it took so much force that if it had to go further it would crack somewhere else. I want it back together in a way that you dont need to worry about for years, and the cracks simply glued feels like it puts too much unnecessary pressure points. Though Im still learning and these are only my thoughts

[RayMan7]

Yeah, a V-shaped splint w/ additional cross-grain reinforcement underneath seems like the way to go with this. This is a seam that wouldn't go back together which I repaired with a V-shaped splint. The cool thing is that you can put hide glue on the splint and then tap it in lightly. It's kind of self-clamping and shows zero glue line. The key is to get the wedge splint the same shape as the groove. I use a reciprocating chisel Stew-Mac used to sell that's wedge-shaped, makes it very easy.

Looks great Marty! Ive never done the self clamping wedge, so thats great to know. I think this is what Im going to do, except the crack is quite wide so I will also need to squish it together a bit, just not as much as I originally did.

[MikeEdgerton]

Yep, once is all it takes, especially with Titebond (or other AR glue).
Looks like I'm in the minority here in thinking a splint should be a last resort. Hopefully, the old glue can be cleaned out and the crack re-aligned.

If it's any consolation it would be my last resort. I'd make sure that mandolin was humidified well before I did anything.

[Bill Snyder]

If it's any consolation it would be my last resort. I'd make sure that mandolin was humidified well before I did anything.

Mike is correct. Before any more attempts at a repair you need to make sure it is humidified for a while.

[RayMan7]

Can you explain a little more on what should I do about the humidified part? Sorry I just havent really learned about that yet

[Bill Snyder]

Frequently cracks occur in the first place because the instrument is subjected to humidity that is too low. When the humidity drops too low the wood shrinks (shrinkage is almost entirely parallel to the grain). As the top and back shrink they have very little give because they are attached to the sides, so they CRACK.
If they crack it helps to rehumidify the instrument so that the crack will want to close back up, or at least come close to it.
To humidify your mandolin you might try something like a Dampit to humidify it (Dampit is only one brand of case humidifier).
Another way to go is put a damp sponge in a trash bag, tie the bag around the neck in such a way that the damp sponge is not touching the mandolin and hang this up somewhere for a few days. Be careful if you do this because you do not want to introduce too much moisture to your instrument.
When the crack quits getting any tighter you have done all the good you can with humidifying and it is time to tackle the repair.
After the repair take care that the mandolin is not kept in conditions that are too dry. Relative humidity of 40-50 percent is good.
Good luck

[sunburst]

...(shrinkage is almost entirely parallel to the grain)...

Correction, that's actually perpendicular to the grain. In other words, the top can shrinks in width but not in length.

[sunburst]

double post

[RayMan7]

Frequently cracks occur in the first place because the instrument is subjected to humidity that is too low. When the humidity drops too low the wood shrinks (shrinkage is almost entirely parallel to the grain). As the top and back shrink they have very little give because they are attached to the sides, so they CRACK.
If they crack it helps to rehumidify the instrument so that the crack will want to close back up, or at least come close to it.
To humidify your mandolin you might try something like a Dampit to humidify it (Dampit is only one brand of case humidifier).
Another way to go is put a damp sponge in a trash bag, tie the bag around the neck in such a way that the damp sponge is not touching the mandolin and hang this up somewhere for a few days. Be careful if you do this because you do not want to introduce too much moisture to your instrument.
When the crack quits getting any tighter you have done all the good you can with humidifying and it is time to tackle the repair.
After the repair take care that the mandolin is not kept in conditions that are too dry. Relative humidity of 40-50 percent is good.
Good luck

Thank you very much Bill, just what I needed to know and very helpful. I will watch the open crack as I humidify it to see how much it moves, then later start the repair.

Thank you everyone! Ive learned so much from here

[Bill Snyder]

John, I mean in width.

[High Lonesome Valley]

I'd go nuclear and turn the crack into a slot (so you get good clean gluing surfaces), insert new wood, reinforce like heck from behind too, then touch up as best you can: that's the hardest part! Hopefully others will have less invasive ideas...

Ditto. To clean the old glue out is only creating another problem that will probably make the crack a de factosloppy slot anyway.

[sunburst]

John, I mean in width.

I thought so, just trying to avoid confusion.

[MikeEdgerton]

The Martin guitar repair manual actually has the repair person forcing liquid down into the crack and then using that to wick the glue down into the crack. The theory is that the wood swells and forces the crack together effectively clamping it. This actually works pretty well on a nice big guitar with a top crack that isn't an eight of an inch wide. I have no idea how it's going to work here but I'm still willing to bet part of that crack is from lack of humidity. I have wedged slices of spruce into top cracks that I couldn't close and it's worked fine as well but that's pretty much been after nothing else moved that puppy closer and it generally requires more work if you want it to look finished.