I recently had to replace the top on a guitar that I had just finished. It is rare that an instrument does not meet my standards but if it should happen it is important that something is done so that potential clients don’t get a bad first impression of my work. For some reason a bad guitar gets a lot more attention than a great guitar. In this case, in addition to the tops, I needed a slightly different bridge and so was willing to sacrifice both bridge and top. I have been told on a number of occasions that one way to get a bridge off if it was glued on using animal glue is to give it a sharp knock with a chisel and a hammer to break the glue bond. I never really believed it but I thought I would try it since both bridge and top were to be sacrificed. No, not true.

Here is what I found: A well-glued bridge will not “pop” off no matter what you do. I think this belief comes from the violin world where they use a slightly different technique and materials to create a more brittle bond. This allows the top or the back of the violin to be taken off with little or no damage to the wood. This is essential for repairs and modifications throughout the life of the violin. A thick glue line is brittle and relatively weak because although animal glue has incredible adhesive strength, its cohesive strength is not great (think concentrated jello). Compare the brittle glue line holding violin top and sides together with the perfect guitar joint. To glue the bridge we mate the two surfaces perfectly and make sure that they are freshly worked. Well-spaced scratches on the glueing surface of the bridge give the glue somewhere to go ensuring that we will not get pockets of glue  (thick glue line). The glue is watered down more than other glueing operations in the guitar and the joint is rubbed to get as much glue squeeze-out as possible. The result is the thinnest glue line possible and a very, very strong joint which can only be dissembled through wood failure. True that enough moisture and heat would cause the glue to re-hydrate and release but this technique is reserved for restorations in which the bridge must be preserved. The photo shows a bridge which was separated from a top by destroying the spruce and shows that adherence was perfect throughout.