QWhen lumber comes out of the kiln at 6 percent MC, shell and core, and is then
put into an open shed, still
stickered, protected from rain and
sun, how much moisture change will
occur in a week? How much if we un-
sticker it first? How much if we wrap
AYou have asked a question that many have asked in the past and still there is no good answer. So, I will give
you my best intelligent guess.
One key is that dry wood, when it
is exposed to 12 percent EMC, will
only come up to roughly 11. 25 to 11. 5
percent MC. This difference is due to
the hysteresis effect.
Temperature of the air has a big ef-
fect on the speed of moisture movement.
End grain has moisture moving 10
to 15 times faster than face grain.
So here is my answer.
Note that when the lumber leaves
the kiln, it might have a temperature
of 150F, so initially and for perhaps 12
hours or longer depending on circula-
tion within the pile in the storage facil-
ity, the EMC for the hot lumber can be
under 1 percent EMC.
The dry-bulb is the wood’s temperature and the wet-bulb is the air’s wet-bulb, which often means about 100F
Air temperature has a big effect on the speed of moisture movement in stored lumber.
“Pinless-type moisture meters are not greatly affected by wood
temperature. They give instant readings and can be used to
scan any location on the lumber’s surface.”