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Thread: Vacuum kilns

  1. #1
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    Vacuum kilns

    Does anyone here have experience with vacuum kilns? Iíve always been told that thick lumber in particular should be stickered long enough to get below 25% and then put into a kiln (a dehumidification kiln in this case).

    Iím curious if vacuum kilns can dry fresh cut stock immediately or if the same rule applies?

    Thanks! Jeff

  2. #2
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    If I could post an emoji of my thumb rubbing my pointer and middle finger I would. Pretty sure vaccine kilns are costly, and awesome.

  3. #3
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    Wood goes into a vacuum kiln completely wet. With super low temperatures in the vacuum kiln, the degrade is really low compared to air drying and then steam or dehumidification kilns.

  4. #4
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    If you go to WoodWeb forum and search for vacuum kilns, there is a wealth of info..

    but yes, it can go from the mill to a vacuum kiln immediately...

  5. #5
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    Small scale, very small, but I have an old vacuum oven I use for pen blanks and small bowl blanks…up to about 7”. Bought it for$50 local pick-up, very stable temps unlike a toaster oven. When starting to dry for stabilization, I’ll draw 28” of vac, but release the vacuum as the temp comes up a little and just use a clamp to close the door. Otherwise, I have no way to keep the vapor out of my pump. When drying after Cactus Juice, no vacuum at all as I want to keep the resin in the blanks. On a larger scale, there must be some way to keep the moisture out of the vacuum system I’d think. Still…really cool to see steam when the oven temp is at 85f!
    earl

  6. #6
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    Matt Cremona uses a drying service that has a huge vacuum kiln. The time (or lack of it) necessary to get his material, which is often very thick, down to where it needs to be is major-impressive. It's a very short period of time from dropping off to load up the device to picking up the fully dried material.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  7. #7
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    Looks like thereís a vacuum kiln just over an hour away. Prices range from $1.25-$3.75 per BF depending on thickness. Whatís most interesting is the idea of less degrading when drying. They claim flatter lumber with less cracking and better color. For walnut this sounds appealing!

  8. #8
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    I agree, Jeff. If I ever manage to get those ash logs at the old property slabbed, I'd love to find a vacuum kiln, although the operation that will likely do the cutting has a more traditional kiln on-site and that may be the easiest and most polite way for me to handle things.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  9. #9
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    Quote Originally Posted by Jim Becker View Post
    I agree, Jeff. If I ever manage to get those ash logs at the old property slabbed, I'd love to find a vacuum kiln, although the operation that will likely do the cutting has a more traditional kiln on-site and that may be the easiest and most polite way for me to handle things.
    Do you have the logs up off the ground? From what I understand ash gets filled with bugs pretty quick when left on the ground.

  10. #10
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    Jeff, they have had 2x material under them presently so they are not in direct contact most of the time. I had to move them recently to clean up a bit (too big to do anything except roll them) and have to force them back onto the sticks. It's mostly ash dead from the borer. Which is sad.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #11
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    You might check with this company about someone close.

    https://idrywood.com/

  12. #12
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    Thanks for that link Kevin.

    Another thought on vacuum kilns: pulling a vacuum should take care of any creepy-crawlies too, right?

    And if thatís true wouldnít that work with a vacuum press bag?

  13. #13
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    I'm doubtful that vacuum alone will assuredly deal with creatures at all phases of their lives, Jeff. But I could be wrong about that. So bagging, no. A vacuum kiln probably has heat involved, too, but I have not checked that out.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  14. #14
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    Jim is correct.... heat is needed and it needs to be somewhere in the neighborhood of 125-140 degree F for a fairly sustainable amount of time..... best to check one of the kiln guides.

    Found this article ... didn't see anything wrong with information.

    https://www.techletter.com/assets/Fi...0TL%202013.pdf

  15. #15
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    Not all vacuum kilns operate the same. Some pull a deep vacuum, and others less so (such as the iDry).

    Wood requires heat for sterilization; vacuum alone will not kill the eggs.

    Most species dry extremely well from green in vacuum kilns. One exception is white oak; it still needs to be air dried first unless it is 4/4.

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