So, as I wrote some time ago, I decided to make the boards for the new ends I am going to make for my concertina by laminating together six layers of horribly expensive Indian rosewood veneer. I had hoped that by now they would be fully dried and ready for me to start on the fretwork. Unfortunately they warped as they dried out. To cut a very long story short:
- I have been convinced that they are probably too warped to use as they are. Particularly as they have warped in two planes in opposite directions.
- They are glued together with hide glue, so in the worst case I should be able to soak them apart and try again.
- I have a few theories as to what went wrong. My main one is that the wood got very wet and expanded during the gluing process, then the glue set so the layers could no longer move relative to each other, then the layers continued to dry and shrink over the next several weeks at different rates in two different directions (because alternate layers are laid at 90 degrees to each other for strength), setting up internal stresses in the boards that could only be relieved by taking on a curved shape.
- Before taking the fairly drastic step of dismantling the boards, I want to try de-stressing and flattening them. For this to work I think I will have to re-activate the glue by applying gentle moisture and heat, and then clamp them flat in a press until they are fully dry, without getting the wood so wet in the process that it builds up internal stresses and warps again. I'm still pondering the best way achieve this.