Messages Archive

Subject:
Blunder? probably
Response To:
Microwave drying???? ()

Bill Tindall, E.Tn.

I have picked up a small piece of wood cut at random out of this stock.

Not sufficient description to determine if this sample is representative. Ideally, the test piece is full width of a board cut from a location well removed from an end.

So, apparently this wood is about at 10% What you know: this sample is at least 10% MC presuming you did not heat it enough to generate volatiles other than water.

resawed it, nothing happened, at least not so far. It would have been most useful to have weighed the freshly resawed piece and followed it weight to see what it did when exposed to living conditions.

Tomorrow I may oven dry a similar piece to see what happens. I hope you take the time to do it correctly.

Have I made some sort of blunder I am not seeing? Likely . How and why in drying does water get out from the center of a piece of wood? First a moisture gradient must be established from the center to the surface. In this case the surface must be exposed to temperature and humidity conditions where the moisture content of the surface is 0. In this situation moisture will diffuse from high to low (just like heat). The "diffusion coefficient" is a measure of the rate at which water diffuses through the wood. To get a water molecule from the center of a 1 x1" block of wood to the surface in 15 seconds would require a diffusion coefficient about 2 to 4 orders of magnitude greater than what I guess it might be. The time scale of your experiment is 100 times too fast.

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