TKiln temp?

Al killian

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1,940
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Floydada, Tx
I have a load of larch for a up comeing job and need to finish drying it. Currently it is over 30% I made a box out of 2x4' and 8 mill plastic. There is a box fan blowing air thru the stack on low and I also hace a small eletric heater in their. What else should I do? How long do I need to keep it in there? There is lumber ranging from 4/4 to 24/4. Stickers are 3/4" thickx 1-1/4" stickers, spaaced every 18" over the 12' On the bottom there are two 8x8" beams with stickers sitting on that. This allows the air under the stack. I allowed 8" of clearance all around the stack for air flow plus 1.5" gaps between boards in each row. Do I need a dehumidfier?
 
al first problem is tha you have some real thick stuff,,that wont dry as fast as the thinner stuff..do a search on the net for dying times for wood specise.. i think larch is near the pine catagory but i dont thin you would want to dry your thick stuff at the same time..in the kilns they usually take the thick stuff and dry it seperatly.. a dehumiderfier is one methode of doing it your self and if you dry the stuff to fast it becomes case hardened and thats not good either.. i only know enought o be dangerous so do a search to get more info...
 
al first problem is tha you have some real thick stuff,,that wont dry as fast as the thinner stuff..do a search on the net for dying times for wood specise.. i think larch is near the pine catagory but i dont thin you would want to dry your thick stuff at the same time..in the kilns they usually take the thick stuff and dry it seperatly.. a dehumiderfier is one methode of doing it your self and if you dry the stuff to fast it becomes case hardened and thats not good either.. i only know enought o be dangerous so do a search to get more info...

And one thing you don't want is case hardened wood. You make a rip cut and have a "Curley Q". This is when the out side dries way before the inside.
Not Fun!
Garry
 
Well I just talked to a sawyer and he told me that Larch is pine, so if I can hold it at 95-100 in the tent then it should take about a week to bring it down the rest of the way. I went thru and put all the 4/4 and 5/4 in a seprate tent. The thicker stuff will be for outside use so that does not need as much drying.
 
Al...

The advice is good. The objective as much as possible is to have moisture migrate evenly out from the center of the boards, and not dry the outside too quickly (which is what results in case hardening). That's why professional kilns have a way to control both temperature and humidity...there are correct combinations of these two parameters that permit even moisture loss (well, never absolutely even, but close enough). Uneven moisture migration can result in internal drying defects as well as case hardening, and they won't be seen until you start working with the board.

Case hardening can be dealt with by taking an additional step. After the final MC is reached you subject the boards to moisture, which re-wets the outside. Then put them back in the kiln for a week. I knew of one guy who stood his boards on end and hosed them down. BTW, we're talking home kilns here and not professional kilns with all this capability built-in.

Woodweb.com is a good suggestion. In particular you can access all the chapters of the "Dry Kiln Operator's Manual"
http://www.woodweb.com/knowledge_base/Dry_Kiln_Operators_Manual.html
I evenutally bought a hard copy of this manual, and have found it to be very useful, even though it's primarily aimed at professionals.

Cheers.
 
I am not to worried about case harding. I plan on taking two weeks to finish drying the lumber. It arrived at around 35% and is now down to 20%. Dehuimedifer is set on its lowest setting, the fan is set on low and the temp is holding steady at 100. All the out side wood is in its on tent and will sit in there for atleast three weeks before I pull it out.
 
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