by Professor Gene Wengert
Q.
Is my air-dried red oak safe to use for casework (book cases, pantry cabinets,etc.) or am I courting disaster? Logic seems to indicate that wood, regardless of the drying method used, will eventually reach a state of equilibrium with regard to the environment in which it is placed. Several texts and magazine articles have not given me a satisfactory answer to this question. I would appreciate any light you can shed on this matter.
A.
Your air-dried lumber in the barn will be at 11 to 12% MC (equivalent to slightly under 65% relative humidity in the barn). In the house, you will likely have a humidity of 30 to 40% RH, which will result in 6 to 7% MC in the wood. Oak is a high shrinking wood (3% MC change equals 1% shrinkage). The basement may actually be dry enough to reduce the MC to the 6 to 7% MC level--is it heated and dry? If the basement isn't dry enough, how about putting a few pieces in the attic for a month? (Not too many pieces or you'll crash the roof down!) It is hot and dry in the attic.
Special note: Kiln drying at temperatures over 130F does two things, in addition to rapid drying--it kills all insects, eggs, and fungi in the wood and it sets the resin in softwoods so the resin doesn't drip or flow at room temperature much, if at all.
Professor Gene Wengert is Extension Specialist in Wood Processing at the Department of Forestry, University of Wisconsin-Madison.
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