What do the luthier's books say about what type of glue to use for permanently glueing a shim under the bridge? It seems intuitive that a hard glue should be used, so as to not soak up any of the vibration down thru the glue joint and into the voice box of guitar. But, is there such a thing as too hard of a glue such as "Resorsinal" (sp) that boat builders use? This glue sets up hard as glass and is waterproof? What about Gorilla glue which is very durable and hard?