Mandolin Seam Separation & Repair
Here are some pictures of a very typical seam separation common on Mandolins, particularly vintage Gibson mandolins. The tailpiece has been removed but is ordinarily anchored directly to the endblock which is being pulled by string tension. When left in a hot environment, an attic or simply neglected this separation can continue until the gap is quite significant, oh, not to mention many of these little guys have been under tension for nearly 90 years or more.
Here you can see the extent of the gap and also catch a glimpse of the end block and kerf lining which serves as a gluing surface between the tops/backs and sides of most acoustic instruments.
I'm pressing the top firmly against the size so you can judge the amount of side distortion and back shrinkage.
If you've been around vintage Mandolin's for some time you've no doubt seen many in this condition.
Repairing Open Seams
The Torture Chamber!
Ok, first I'll start by saying this is not always an easy task. I've had many that cooperated wonderfully and came back together with little evidence of their former state AND...I've had those that would bring hair loss and tears.
By using the jig pictured above I am able to apply pressure at any given point, but bare in mind that each action can have an equal and troubling reaction.
Since most of the Mandolins I see in this condition are going on 80, it is not uncommon for their old seams to be brittle or weak. When exerting pressure on one point we are likely to spring any weak seams and may end up gluing a far greater area than the initial open area.
I often explain the procedure as taking a small lid and trying to place it on a large can. And indeed if the back has shrunk or the sides have distended a good deal, this is a fair description.
In the case where the deformity and gap are significant we are often limited to the results possible. I have heard of some shops that actually route a binding channel (when there is none) and install body binding to disguise this misalignment, something I don't offer.
In the picture above you can clearly see the ledge evident after the repair. Tremendous pressure had been applied in an effort to close this seam but unfortunately it could not come back together perfectly.
In an effort to increase the likelihood of a successful repair I insure that the instrument is properly humidified and as pliable as possible.
