Drying 6/4 and 10/4 at the same time

[Geeg]

Just wondering about drying both 6/4 and 10/4 hardwood. Should this be done? and if so should the probes be inserted the 10/4 boards?. My guess is that the 6/4 boards will be drier at the end of the cycle.

Any input would be appreciated.

[scsmith42]

If I go into my Nyle with green oak, 6/4 flat sawn is around a 7 week drying cycle.  10/4 would be 5 months.....

Typically I use my solar kilns as pre-dryers for thick oak.  10/4 is around a 1 year cycle with the first 6 months of that having 3/4 of the solar collector blocked off.

[doc henderson]

maybe if you follow the MC of each dimension, you could pull out the 6/4 when it is at your goal MC.

[Geeg]

If I go into my Nyle with green oak, 6/4 flat sawn is around a 7 week drying cycle.  10/4 would be 5 months.....

Typically I use my solar kilns as pre-dryers for thick oak.  10/4 is around a 1 year cycle with the first 6 months of that having 3/4 of the solar collector blocked off.

Sorry, I forgot to mention that the 6/4 and the 10/4 has been air drying for 2 years.

[doc henderson]

what is the current measured MC of each thickness?
what are the plans for the wood after it is dry?
What is you target MC?

[Geeg]

what is the current measured MC of each thickness?
what are the plans for the wood after it is dry?
What is you target MC?

Both measured MC are 20-25
use will be for paddles and furniture
target is 6-8 MC

[scsmith42]

You should be ok mixing them.  I'm surprised that the MC% is so high after 2 years of air drying though.

[KenMac]

I also have a Nyle l200, but it is old- around 2000 0r so. It has no fancy monitoring equipment from Nyle but I installed a cheap temp an RH monitor for the return air. My question is this: If relative humidity is maintained to dry the 10/4 wood at its' proper rate , won't the 6/4 be the same MC- or at least very near the same? Wood moisture is, after all, dependent on surrounding RH, is it not?

[doc henderson]

yes if you set it for that EMC.  but to get things to move the controls (RH and heat) are set lower than that MC as all things are on a gradient.  if set so it stops at the desired MC, it will take longer esp. for the thicker, I think.  the thinner stuff can be dried faster than the thicker as to not create defects.  I would set it for the thicker, and take out the thinner when it gets to your desired MC.

[Geeg]

yes if you set it for that EMC.  but to get things to move the controls (RH and heat) are set lower than that MC as all things are on a gradient.  if set so it stops at the desired MC, it will take longer esp. for the thicker, I think.  the thinner stuff can be dried faster than the thicker as to not create defects.  I would set it for the thicker, and take out the thinner when it gets to your desired MC.

I think I agree with you Doc, I have set the stack up to lift the thin stuff out if and when needed, Thanks for everyone's input, much appreciated.

[scsmith42]

yes if you set it for that EMC.  but to get things to move the controls (RH and heat) are set lower than that MC as all things are on a gradient.  if set so it stops at the desired MC, it will take longer esp. for the thicker, I think.  the thinner stuff can be dried faster than the thicker as to not create defects.  I would set it for the thicker, and take out the thinner when it gets to your desired MC.

Doc, I concur with your comments.  The only challenge with this approach is sterilization.  Typically the sterilization cycle is run at the end of the kiln cycle, and then conditioning afterward.  
For the highest quality hardwood, if the 6/4 is removed early the kiln operator would need to run a sterilization cycle before removing the 6/4, condition the entire load, remove the 6/4 and the finish drying the 10/4, and condition the 10/4 a second time.

[Geeg]

UPDATE:

The 6/4 was removed at 6% and the remaining 10/4 stack is sitting at approx 11%.

I figure another 3-5 days and then I will put the 6/4 back in for the conditioning and bug kill cycle.