Flexner on Finishing: Finish Both Sides? Not Necessary.

Leaving the underside of your tabletop bare doesn’t cause warping.
By Bob Flexner
Pages: 110-111

From the October 2004 issue #143
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Logic is usually a good guide, but it doesn’t always apply. A case in point is the widely held belief among woodworkers that the way to prevent warping is to apply finish to both sides of a board.

This practice does seem to make sense at the outset. Moisture exchange is responsible for warping, and a finish slows moisture exchange. So assuming the wood was properly kiln-dried to begin with, if the moisture leaving or entering the wood from changing humidity conditions is equalized on both sides, wouldn’t this prevent warping?

Not at all.

From the October 2004 issue #143
Buy this issue now