Just to show you that some ideas do not work out so well. It has been a while since I built a laminated instrument, with a fancy burl veneer on the outside, and Pennsylvania black locust on the inside (one of our best local tonewoods, I have heard it referred to as the ‘rosewood of the east’). Anyway, I got some really nice redwood burl veneer and figured I would pair it with a redwood top for an all-redwood instrument.
I glue the veneer to the locust with a catalyzed urea veneer glue which you mix up with water and it sets via chemical reaction. Since the glue is water based, the water in the glue does swell the wood a bit when it is applied, particularly the veneer. I have done this in the past and while there was a little cupping of the surface, it was not bad and things could be wrestled into final ukulele shape.
This time however, things were different. The redwood burl veneer seems to react with the water in the glue in a pretty extreme way, so that when things dried out the veneer pulled the whole back into a major cupped piece. I figured, what the heck, and applied the back braces, hoping that would pull things into shape. Actually it just made things worse, and shifted the cupping around. I ended up with this:
That is clearly not going to work very well. Into the trash it goes!
I have re-made things using epoxy as the glue. Since epoxy does not contain any water, things stayed nice and flat. Anyone want to buy some unused veneer glue?