Movement in walnut or plywood?
I recently made a large top for a receptionist desk in kiln dried walnut. I used 3/4" stock in varied widths with glue and wood biscuits on the lengths and ends of the wood. Since it was a large 'L' shaped top and I wanted the look of a thicker slab, I cut a piece of 3/4" plywood to the same shape and screwed it to the bottom of the joined walnut. After about two months, the entire top is 'cupped' and far out of square. Is this due to the Walnut not being acclimated?