Hand Tools

Subject:
wood chemistry

Bill Tindall, E.Tn.
These things can be studied and have been. Wengert, when he was at VA Tech did some nice work on the topic and demonstrated that wood drying cycles exhibit hysteresis. That is a word that describes a situation where a cyclic input does not yield the same result as the cycles are repeated. In this case if wood is air dried under some humidity that results in 12% MC, then dried to 4% MC in a kiln, then expose to the same humidity the wood recovers to something less than 12% MC. Each cycle the wood recovers to a lower EMC.

The drying to less than the equilibrium moisture content (EMC) bakes out hygroscopic stuff and changes the crystal structure of the cellulose so it does not suck up as much water.

Many are invested in the notion that air dried wood is superior and they dismiss this result. I have observed that these people usually have some other strong reason to make this claim such as not having access to a kiln to dry cheap wood they have obtained or KD wood. I have quit arguing with them. A famous scientist once offered, that "people that arrive at opinions not based on facts are unlikely to change their opinions when presented with facts.

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