" Alien " style back crack…..Exploded from within..

[thefishinmusician]

Got a Martin here from the place I do repairs for that had a boo-boo happen while at a display at the State Fair…I can't figure out how it happened , but it looks as if it had exploded from the inside..The sides are glued but this section you'll see in the pics popped out…As you can see , it's a full 16th away from going back together , and it's like that all the way up the main crack..The only thing I can think of is loosening the whole seam on the broken side to relieve the crack…Any ideas ?

[Len Biglin]

It seems there must have been a lot of compression built up in the back , it also looks like the mohogany was not quarter sawn , it you look at the grain exposed in the depth of the crack , you can see the silk of the quarter , which should rightly be seen over the surface of the back . In other words it is completely off the quarter and wants to crack. Im not about to instruct Martin on guitar making , but thats how it looks to me . Any thoughts ?

[LARRY KLOSE]

I have limited experience but the few encounters I've had with off-quarter sawed plates is that the crack won't be perpendicular to the finished surface--it'll be at an angle to 90 degrees.  Is that not true.

I had a flat sawed RW back on an instrument that was way off quarter and needed several crack repairs.  All the cracks were angular rather than perpendicular. 

[Paul Breen]

Original owner Martin warranty? Might want to check on that. If not, doesn't look like any choice but to release the back on the damaged side or replace the back. There is no binding, so that will make the job a bit easier.

[thefishinmusician]

Belongs to the music store…At the state fair , where they had a booth ,a lady knocked it over or something….Release the back seems like the only alternative...

[Paul Breen]

" A lady knocked it over or something...."

No warranty covers that!

Better check the back braces really well.

[Len Biglin]

Hi Paul , do you have an opinion about the flat sawn theory above ?

[Paul Breen]

Unlike the top, I do not believe that quartering really makes much of any difference for a back. Most of the structure there is provided from the braces. It does appear though, as already pointed out, that the instrument was either built with or more likley, accumulated a lot of tension. What was the humidity like that day? Was it sitting in direct sunlight? Seems to me that factors like humidity and baking in direct sunlight would be likely culprits for the tension.

[thefishinmusician]

Not sure if it was in the sun…Summertime humid...

[thefishinmusician]

Oh…That's part of it..