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Author Topic: kiln and air drying  (Read 3373 times)

Offline builditbill

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kiln and air drying
« on: May 23, 2013, 11:58:45 AM »
#1 I am going to build a dh kiln and would like to know if i should hold off cutting until its built and load directly or is it ok to cut and stack and let it air dry until the kiln is done? will this effect the wood  for good or bad?
#2 My local hardwood /exotic wood supplier has some African and south american logs that were cut into 2" slabs then stickered and banded back together I dont know if it has been kiln or air dried. Does any one see a problem with this or is it something I could do with some big red oaks I have and let it air dry.

Offline Post Oakie

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Re: kiln and air drying
« Reply #1 on: May 23, 2013, 12:59:23 PM »
builditbill, there is no problem air drying the wood before putting it into the kiln.  The biggest issue is that you'd be handling the wood twice.  I recommend end coating the logs (Anchorseal is my first choice) before milling them to reduce the end splitting.  The catch is in knowing the moisture content of the wood going into the kiln so that you can bring it in at the right point in the drying schedule.

Exotic woods can be tricky, especially if the species is unknown, since the properties vary so much.  In this case, you would absolutely need to know the moisture content.  Get a pin-type moisture meter.  For the exotics, you may want to perform an oven-dry weight test to calibrate the meter to each species.  That will give you an idea of whether you want to kiln dry the wood, and where to start.  You can't just throw a mixture of species and moisture contents together in a kiln and get good results.

Check out these links from the Forest Products Laboratory.  They will give you a good foundation on drying wood.  And let us know how it goes!
Air Drying Lumber  http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr117.pdf
Drying Hardwoods  http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr118.pdf
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Offline Stevem

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Re: kiln and air drying
« Reply #2 on: May 24, 2013, 08:38:16 AM »
Banding green wood is good 'till it shrinks and then you lose the tension.  Straps that can be tightened would be one step up.  Add a spring in the system and only tighten ever so often.  Weight  and lots of it, is the old standard.  Wood that tends to move alot needs more weight and slower drying time.  End sealing tends to slow the drying time because moisture will move out of the ends of boards more than ten times faster that the sides and produces strain (read cracks) in the wood.  Also knots in flat sawn wood don't shrink as much as the rest of the wood and tend to put bends in the board. 
Stevem
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