Ok so i have a this stack of maple thats been air drying in the garage (with a fan for air flow) for the last 4 months. I dont have a moister meeter but the last time I rotated it and re stickerd it I noticed it has lost a considerable amount of weight just judging by feel
So since its starting to heat up here in Utah and the space up in the rafters in the garage get nice and hot in the summer probably around 120 degrees during the day, you think I would be safe to move it up there to finish off for a month or so once the temp gets heated up. Also I will add the fan up there to keep the air flow going.
Am i looking for trouble by doing this? I have never dried my own wood but i think this is coming along nicely, with very little twist and no checking. So i dont want to blow it now
Replies
I think you are probably safe in moving it to the attic area. Just keep it well stickered and weighed down. You are not going to get to 120 degrees anytime soon even in that attic. Do you have good air circulation through the attic? That is mandatory of course. I store my air drying lumber in a barn attic all year round. I have an open cupola at the roof peak and a access door in the inside ceiling. When that is open, there is a strong updraft that results in a high air flow through the stacks. I can dry 5/4 cherry from 20+% moisture to <10% in just a few months. I now have a pile of maple and a pile of aspen that has been drying all winter. Here in NH, the RH at this time of year is low so drying is fairly quick even at the low temperatures. The maple was cut last September and dropped from 20%+ to <8% inside of about 3 months.
wood web has excellent info on sawing and drying
http://www.woodweb.com/knowledge_base/Wood_and_Water.html
do the oven test. I have used it numerious times to figure moisture content. your not going to get below 15% air drying.
if your rafters get hot in the summer you can get it down to 10% but be carefull if you overdry it will really destroy the wood; it will take a long time for the lumber to regain moisure and it will machine like crap.
doesn't the RH determine how dry my wood will get? If the average RH outside is 39% wont the wood come down to about 7% MC?
Closer to 8%, but yes. Note that it follows sort of an exponential decay curve; the initial water loss is rapid, but it slows down as you get closer and closer to the equilibrium level.
-Steve
it's not exactly that easy to answer. Eventually yes if you’re willing to wait. There are limits to how much water will come out in a given amount of time. the only way to force more water out is a vacuum kiln.<!----><!----><!---->
you will need to bring it into a conditioned air space (inside your house) if you want to get it down below 10-12% and wait a long time. it took 2 years for the red elm I cut to completely reach 10% in my shop. But 200 b/f 4/4 red oak was ready to go in 9 months.<!----><!---->
I cut 700 BF of cherry this last fall and it was 12-14% in less than 60 days... but now it's just sitting very slowing coming down; like less than 10-13% in the last 3 months.<!----><!---->
I think it varies a lot from tree to tree and the time of year. even boards within the same tree will vary greatly in how fast they loose water.<!----><!---->
Picture of the cherry getting ready to be bucked. also see the big red-ended red oak. It’s still at 15-16% and it's been inside a heated shop in <!----><!----><!---->Minnesota<!----><!----> in the winter. Very low RH and that was September when I cut it.<!----><!---->
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Also some common ash I cut that took well over a year to come down to 10%. made paneling and matching doors for the downstairs.<!----><!---->
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you will need a way to determine moisture content. Oven test? Otherwise there is not other way to know exactly what's happening.<!----><!---->
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good luck.<!----><!---->
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At least where I am (up north), one way to at least get a step ahead of the moisture issue is to cut the logs in winter. At this time of year most trees are in the dryest condition of any other season.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Once you start pushing the drying process the risks of damaging the wood start rising quickly with no gain other than getting the wood dried out faster. Unless you are in a big rush, let the wood finish drying where it is now.
Also, unless you can closely monitor the drying, the wood will become drier than the typical equilibrium moisture content and will need to be allowed to gain some moisture after it comes out of the attic using up some of the time savings.
John White
Two additional comments. First, be sure the rafters can support the weight of the boards. I know of at least one woodworker who was hurt when he had a partial collapse of his shop ceiling.
Second, heat is a minor secondary factor in wood drying. The primary item you want to control is relative humidity.
Wiskeytango,
NO!
Now is when case hardening occurs and in extreme cases honeycombing.. For those not noticing it,, he's in Utah and Utah tends to get very dry and very hot in the summer.
An attic could have temps in excess of what be proper even for a kiln
Edited 3/6/2008 9:49 am ET by frenchy
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