# Kiln drying question...



## Mike Jones (Jan 18, 2013)

Don't want to hi-jack jimmyjames' thread RE: drying his maple slabs....(seems he's having about as much fun as Nebraska Law allows )....but,
my question is this. Why is the target moisture content at 6 to 8 percent?
If jimmy were to go to the lumber yard and buy kiln dried lumber, he'd be hard pressed to find anything less than, maybe 12% right? And, if you know that your project wood is going to assimilate to ambient MC, why not check the MC of wood that has been in the house for awhile, and use the average of various readings as the "target"?


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## Kevin (Jan 18, 2013)

Because that's the way it's always been done. 

For one reason, most high end furniture makers and cabinet makers want it that low. Wood suppliers that cater to them know this and will store their KD wood in a way that does not allow the wood to go back up to EMC. This is more rare now since most hobbyists store their wood wherever they can without regard to what EMC is. Kiln schedules are all designed around reaching this target of 6% or close to it, and large kiln operators that dry high grade hardwood use these schedules solely. What the middleman or end user does with it is not their problem. 

You may ask why dry so low if the end product is going to be subjected to EMC anyway? Several reasons. Even though wood does not move appreciably below EMC it still does have a bit of stress to release, so thinking 6% is about as low as wood will ever see is a good target to reach for stress release. 

None of this is fact just my opinion based on experience and reading various articles over the years, and there's other reasons for it as well but lunch was just put in front of me so this post is at an end. :eat:


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## woodtickgreg (Jan 18, 2013)

And for what it's worth and to just make things more confusing, I just air dry my lumber with the old year per inch rule that everyone has an opinion on, then I bring it inside for a while before I use it to let it acclimate to the humidity in the house. Never had a problem with any species, if I get checks or splits from the air drying process, I just cut around it, when it splits or checks I call it stress relieved.  My jointer is only 8" wide anyway so ripping boards to that width to work around cracks and checks is no big deal imo.  I am a hobbiest and I have a nice size stash of lumber that was all free except my labor to mill it, so I'm not gonna snivel about a few checks or cracks in a few boards, most are a o k.


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## NYWoodturner (Jan 18, 2013)

Kevin pretty much said it all. The only thing I might add that might make sense of drying to 6 or 8% knowing it will move to EMC is that when you make good joints at 8% and it moves to 12%, they are VERY tight joints. When I made furniture that is the main reason I looked for the lowest MC.


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