Q:

I used 3/16-in.-thick resawn walnut, glued to plywood, to make a tabletop, but did not veneer the underside. I finished it with an oil/varnish mixture. The seams have opened up and the top warped. What went wrong?

Mike Baumgardner, Marietta, GA

A:

Your resawn veneer is too thick and is acting more like solid lumber than veneer, expanding and contracting in tune with seasonal changes in humidity. There are several things that you can do to minimize this movement.

Keep veneers thinner than 1/8 in. The thinner the veneer, the less prone it is to seasonal movement. Second, allow veneer to rest in the shop for a few weeks before using it, so that its moisture content reaches equilibrium with the shop’s humidity. Third, joint and glue the seams together before gluing the veneer to the substrate, and wait a day to allow the water in the glue to escape from the seam area.

Finally, use an extra coat or two of varnish as a moisture barrier between the veneer and the atmosphere.

Photo Caption: Glue edge joints before laminating. This should keep them from opening up, if the veneers are thin enough. Use blue tape as a clamp.

Photos: Staff

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