depression. So, the wood will actually
dry a little more for the first 12 hours
as it cools. Then it will begin to gain
moisture. So, after 24 hours, you are
likely at “no net change” overall.
Note that this drying while the
lumber is hot is why it is a terrible idea
to process lumber right out of the hot
kiln. A minimum of 24 hours is needed
For 6 percent MC lumber, still on
stickers, exposed outside (protected
from rain and sun) to 12 percent
EMC (typical for much of the U.S.
summer and winter), at an average of
70F, I would expect that in four days
exposure, the outer 1/8 inch would be
close to 10 percent MC average. The
next 1/8 inch depth would likely be 7.0
to 7. 5 percent MC. The end grain loses
moisture much faster than face grain,
so this effect might be 10 times deeper
on the ends; that is, the 10 percent MC
might go about 1-1/4 inch up the ends.
For lumber that is tight piled, the
moisture in the air will have a hard time
getting into the pile, unless there is wind.
So, I would expect that the pieces of lumber on the outside would change quickly,
but on the inside, the change in three
weeks would be fairly small throughout.
Perhaps, an unstickered, flat piled stack
would change seven to 10 times more
slowly than lumber on stickers.
When you wrap lumber in plastic, no
moisture can get in or out, so there will
be no moisture change overall, except
that moisture might move within the
wood. The average moisture will stay at
the original value for years, even with
sunlight and rain (if no holes) if wrapping “seals” all six sides of the pack,
whether flat piled or still on sticks.
WOOD DOCTOR’S Rx
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“Note that this drying while the lumber is hot is
why it is a terrible idea to process lumber right
out of the hot kiln.”
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