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<DIV>Word document with formula etc. is attached. I think the formula =
can be
useful for getting some kind on an initial guesstimate of how long to =
expect a
piece of wood to dry. I don't think it will be very useful for =
predicting how
fast a soundboard panel will go from 9% MC to 6% MC.</DIV>
<DIV> </DIV>
<DIV>I have found the best way to closely monitor wood MC is by
weighing smaller pieces and/or measuring across grain of a =
panel. I
have two panels in my hot box right now. They've been in there for six =
days at
about 92 degrees F and 27% RH. They have shrunk 3.5 and 5 mm as of today =
and
they are still shrinking. What I do is take them down a tiny bit drier =
than I
want them (if target is 6% MC, I'll go to 5.5% or anything a little =
lower than
6%) and then let the RH rise just a tad and make sure they grow a =
tiny tad
- that way I know for sure the panel had equilibrated at the lower RH - =
if it
still seems to shrink, go tune pianos for a week and then go back and =
check the
hot box. Weighing samples works quite well also - although you always =
will
wonder if the sample is drying a litte faster because of its increased =
surface
area/volume ratio, and its increased percentage of end grain.</DIV>
<DIV> </DIV>
<DIV>I also found a reference to the two soundboard CLAMP =
articles:</DIV>
<DIV> </DIV>
<DIV>David Hughes soundboard press in PTGJ is August 1993</DIV>
<DIV> </DIV>
<DIV>Clair Davies soundboard press – August, September, October =
1997.</DIV>
<DIV> </DIV>
<DIV>Terry Farrell<BR></DIV>
<DIV> <SPAN id=__#Ath#SignaturePos__></SPAN> </DIV>
<DIV>----- Original Message -----
<DIV>From: <<A
href="mailto:BobDavis88@aol.com">BobDavis88@aol.com</A>></DIV>
<DIV>To: <<A =
href="mailto:pianotech@ptg.org">pianotech@ptg.org</A>></DIV>
<DIV>Sent: Saturday, August 09, 2003 11:24 AM</DIV>
<DIV>Subject: Formula for rate of change of EMC?</DIV></DIV>
<DIV><BR></DIV>> I know a while back someone posted the formula for =
rate of
change of EMC over <BR>> time. It was based on the ambient humidity =
and the
thickness of the wood. <BR>> I've been looking through the archives =
and
through the Wood Handbook, and I can't <BR>> find it. Probably =
staring right
at it. Anyway, will whoever?<BR>> <BR>> Thanks<BR>> Bob =
D<BR>>
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