Wood MC Puzzle

[Farrell]

This is a multi-part message in MIME format.

---------------------- multipart/alternative attachment
I'm trying to figure out why a piece of wood is not behaving itself.

On 11/6/02 I cut a piece of spruce out of an old soundboard and sanded =
the finish off. It weighed 91.71 grams. Environmental conditions in my =
shop, where the soundboard had been for months were pretty constant at =
75EF and 45% relative humidity (RH). According to Dept. of Forestry =
data, wood under those conditions should have a moisture content (MC) of =
about 8.4%.=20

I dried the spruce in my kitchen oven to zero MC (monitored weight =
periodically until no change was noted for about an hour). The oven =
temperature cycled from 210EF to 250EF (set the oven to 225EF) during =
the four-hour drying process. When dry, the spruce weighed 84.55 grams. =
Working backwards to calculate the MC before drying indicates the wood =
was at 8.47% MC - real close to what the Forestry data suggested it =
would be. OK so far.

I took the spruce out of the oven at zero MC and set it in the shop and =
periodically weighed it and calculated MC. Last night, after three weeks =
of regaining moisture in my shop, the spruce weighed 89.80 grams. This =
calculates out to a MC of 6.21%. Three days ago, the wood weighed 89.76 =
grams, or a MC of 6.16%. Clearly, the rate of moisture accumulation in =
the wood has almost leveled off. Not OK now.

The shop has been consistently at a temp of 65EF and RH of 45% for weeks =
now. That should equate to a MC of about 8.5%. I find it hard to imagine =
that my little piece of spruce will gain enough moisture in my lifetime =
to get back up to 8.4% or 8.5% MC.

Anybody have and great ideas of why the wood seems to be staying dryer =
after the cooking process? Is 250EF too hot - has it changed the wood =
somehow so that it can't hold as much water? It looks the same. What is =
going on? Anyone know a professor of wood technology?

Under what environmental conditions do commercial wood drying kilns =
operate?

Thanks.

Terry Farrell
  
---------------------- multipart/alternative attachment
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/27/16/1b/1c/attachment.htm

---------------------- multipart/alternative attachment--