I just got some 2" planks of walnut that I am looking to convert into a
table so will have to glue up several boards.
They are currently about 8 feet long and have perhaps 2" of cracks at
Boards were stored outside, but in a shed at sawmill - but not sure how
long they were aged after cutting and my acquiring.
The end cracks don't seem to be increasing in length since I've gotten
the boards but they are stacked in an outside garage with high humidity
Before I commit to cutting the boards to length any input on how long I
Thinking also of moving the boards inside to a lower humidity for a
month or so to see if this changes the drying process/
Air-dried won't get below about 15-20% and will have undoubtedly
reacquired some if was below that if has been in a humid location.
Around 10% or lower is desirable for stability for inside use.
"Rule of thumb" is about 1-yr in dry location/inch of thickness to reach
equilibrium w/ outdoor levels.
Ideal would be to arrange a solar-kiln to dry this some more, otherwise
unless you have quite some time to wait and a really dry location to
store it, you're likely to experience grief when it is sawed/planed and
fresh surface is exposed.
More trouble can be expected in drier locales and colder areas where
winter heating causes really, really low RH's, less (but not zero) in
more humid, temperate areas.
I'm not trying to be flip, but I've put my ligno on lots of air-dried
wood and gotten readings of 10 percent and under. Is the meter that
far off? Checks on green wood and kiln-dried are always in the range
I'd expect, except it redlines at 20%.
How old and what species and are you sure you got a reading
representative of the innermost section(s) of the material?
_Eventually_ in an indoor environment w/ climate control it will dry. I
was speaking (although I didn't specifically condition it) of relatively
new-sawn material that had only been outside...
No, this is a misunderstanding. It dries after a month or two, even when
relatively fresh. Why it stops moving after some years is because it
stops _moving_, not that it stops changing its moisture content.
As to "You can't air dry below 15%" then that's just wrong. If it were
true, then we wouldn't have a problem of complete pieces made of 15% MC
timber drying out even further after compeltion and then cracking!
Read Hoadley or the on-line copy of the Forest Products handbook.
You are correct, and your meter probably is close as well. Wood is "best"
at the EMC (equilibrium moisture content) of the place where it will reside
as a finished piece. Different in San Francisco than Phoenix, that's for
Woodturners weigh their stuff to ascertain if it has equalized with the
Relative Humidity of the air around it, and if you're curious, you can use a
meter or a humidity gage to determine numbers. Which don't mean a lot in
terms of stability, since the wood will gain or loose moisture and change
dimension along with changes in relative humidity.
Free good stuff at
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm for the
download. Chapter three will tell you how wood dries.
My air dried wood stabilizes at about 16% moisture in western Wisconsin.
I just got a new Ligno ??? ($198) and tested a lot of stuff; walnut,
basswood, white oak, cherry, black ash, elm, etc. and it was all pretty
much the same when I read it in March. Some if it (it's all stickered)
has been out there since 1978, the most recent was put there about 5
years ago after the saw got done with it and it sat outside, under
cover, stickered for a year.(There's about 10,000 bd ft of it out there
and mabye we will finally get to some of it).
A friend who lives close by, and is very conscientious about getting
to the 6-8% range has installed 18 inch wide shelf brackets all the way
around the top of his heated shop, about 2 feet down from the 10 foot
ceiling. On these shelves he stacks the air dried wood that is next to
be used, for a month to 6 weeks before making furniture. Says that
does a great job of getting to his 6-8%.
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