What to do about a hairline crack?

[first string]

Well as you can see my question isn't about a mandolin so much as a tenor guitar. But I have it tuned GDAE so hopefully it counts. Besides, where else could I gain access to the knowledge of so many talented and experienced luthiers. So my problem is that I recently bought this tenor guitar from an online dealer. It was advertised as crack and repair free, but after having it for a few days (and handling it very carefully I might add) I found what appears to be a hairline crack, just north of the back seam. It doesn't appear to go all the way through, but I'm hardly an expert. Anyway, I'm a little bummed about it but my approval period has expired. Besides which, I love the sound of this instrument in a way that is hard to describe. I doubt that I could find another that I would like as much, and I don't suppose a little crack is really that big of a deal on an instrument that is 67 years old. My question is, what should I do about it? I'm going to keep it, but I would like to do something to stabilize the crack before it gets any bigger. Being that I don't think it goes all the way through, can it be filled with glue?

I'll probably take it to someone as soon as it gets a bit warmer out. I don't have a car, and taking it out in the cold doesn't seem like it would help things. I'm also going to purchase a humidifier for my apartment next weekend. But in the mean time can anyone tell me what I'm looking at in terms of a repair?

I'm including a few pictures. Sorry they're too big. I tried unsuccessfully to scale them down. You can see the crack by scrolling over to the right. The crack is about two inches, but it looks like it might be spreading.

Also, does anyone know of a good luthier in the immediate DC area?

Oh, one other question...I’ve heard that the pick guards on these old Martins sometimes shrink and cause cracks on the top. Should I be looking at having it replaced with a modern pick guard? Or would that be sacrilege? Opinions please.

Cheers.

[first string]

http://i176.photobucket.com/albums/w192/northlight/IMG_1710.jpg

[first string]

http://i176.photobucket.com/albums/w192/northlight/IMG_1712.jpg

[first string]

http://i176.photobucket.com/albums/w192/northlight/IMG_1713.jpg

[sunburst]

The crack(s) should be fixed, and the sooner the better. Not an emergency, but the sooner the better in terms of how the repair will look.
I'm a couple of hours away from the DC area, and I could glue them, but it would probably cost more to get the guitar to me than I'd charge you to fix the cracks. I don't know anyone closer right off the top of my head, but I'll keep thinking.

The pick guards can cause cracks, but if there aren't any "pick guard cracks" yet, I wouldn't replace the guard.
On older instruments like that, rather than use a new pick guard, I prefer to remove the guard, fix the cracks, apply a finish on the bare wood, and replace the original guard. Having a finish under the pick guard, and a flexible adhesive holding the guard on keeps the differential shrinkage between the plastic and the wood from causing the cracks. The pick guard can instead "float" on the top. Modern pick guards are usually the same material. The material wasn't the problem so much as Martins former method of applying the pick guard to the bare wood and finishing over it. Now they apply the finish first and the pick guard later, and those cracks are no longer a problem.

[Bill Snyder]

Well I am not going to suggest to you that you attempt to fix this yourself. You could make a mess of the finish very quickly and the finish looks to be in good shape for a 67 year old instrument.(Very good photo of the crack by the way.) Looks to me like there may some more cracks starting just above the bad one. I would suggest that you make sure that where you are keeping the instrument is not too dry. Do you have any idea what the RH is in your home? If you can't humidify the whole house you might try to humidify one room.

EDIT: If John is within a couple hours of you I suspect he would be a very good choice.

[nelson_luthier]

I was going to mention the RH as well. Where did this instrument come from, and what is the RH where you are now? You can easily make a high humidity closet to keep this in by hanging a wet (not soaking) towel in a small closeet where you keep it. That's just for emergency situations, like here in California when the Santa Anna Winds come. The RH can drop like a stone when they kick up.

I would only use Hide glue to fix this crack. That's your best chance of keeping the finish intact. Some would be able to do it with white glue, but you have to be super diligent with clean up. Once the glue is in place I would wrap the body with some huge rubber bands I got from a moving company. Some people use cut up inner tubes. Both would work fine. If the crack returns you may want to consider some patches on the inside to help hold it together.

Greg

[first string]

Thanks guys for the responses. I don't know the exact humidity, but I am going to buy a humidifier this coming weekend, and it should be able to handle my whole apartment (I live in a studio). To answer your question Greg, I purchased it from Bernunzio in Rochester NY, so I guess it could have gone through some pretty radical different tempatures and humidity levels on its way South. I've considered sending it back to Bernunzio and asking them to repair it, as I have had it for less than a week, which seems like a pretty short time for it to have cracked (I know it's not that dry in my appartment) but I really love this instrument, and I don't want to intrust it to UPS again.

John: I'm going to send you a PM.

Thanks again guys.