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Thread: Food dehydrator for bowl blanks?

  1. #1
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    Food dehydrator for bowl blanks?

    I've been watching the wood whirler on YouTube. He seems to have something going with a food dehydrator. I found nice blanks at a good price, but they are cut green then waxed. I'd like to find some way to get the moisture down, without waiting till I'm dead to make something out of them. Have any of you experimented with a food dehydrator?
    Where did I put those band aids?

  2. #2
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    Quote Originally Posted by Dueane Hicks View Post
    I've been watching the wood whirler on YouTube. He seems to have something going with a food dehydrator. I found nice blanks at a good price, but they are cut green then waxed. I'd like to find some way to get the moisture down, without waiting till I'm dead to make something out of them. Have any of you experimented with a food dehydrator?
    I have not experimented with using a food dehydrator for drying wood blanks or heard of this from other turners. (I prefer to air dry wood.)

    Maybe describe your blanks. Do you mean you want to dry a complete, unturned blank such as a section of logs? How large? What species? (Some species are more stable than others)
    Or are these blanks cut from logs or rough-turned in a way they can be dried successfully?

    I process and dry a lot of wood. Due to the nature of the structure of wood drying a large solid blank can be tricky.

    JKJ.

  3. #3
    While his experiment may have merit to me its flawed. When he removed the 3/4" thick bowl out of the dehydrator he tested the moisture with a meter within 10 seconds and called it dry. Those meters only read as deep as you can jam the pins in the wood. The surface of that bowl was dry but who knows if the center was without letting it sit for awhile and retesting it. Like John said give us the dimensions and type of wood the blanks are made out of and someone can give you ideas of how to dry them successfully.

  4. #4
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    Just my $0.02, I would not do anything with the blank. I much prefer to turn green/wet wood, it cuts easier, less dust in the air, lots of reasons. The downside is I have to twice or three times turn everything....... Oh, if you turn it green, you avoid the possibility of a crack that could ruin the whole blank, downside, if it cracks when whole, chances are that it may crack after or during roughing.

    However, the original question is very good, I do wonder about that. I have a fridge kiln (Google Cindy Drozda fridge kiln) and am very happy. Cost me around 50 bucks total. Drying roughs in the fridge kiln takes 3 or 4 weeks. I would like to know how fast/slow a dehydrator can dry roughed bowls...... Got some rather large and pricey dehydrators out there.

  5. #5
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    Quote Originally Posted by Kyle Iwamoto View Post
    ...However, the original question is very good, I do wonder about that. I have a fridge kiln (Google Cindy Drozda fridge kiln) and am very happy. Cost me around 50 bucks total. Drying roughs in the fridge kiln takes 3 or 4 weeks. I would like to know how fast/slow a dehydrator can dry roughed bowls...... Got some rather large and pricey dehydrators out there.
    I still want to know if when the OP said "I found nice blanks at a good price, but they are cut green then waxed." is he talking about drying solid, unturned green blocks of wood or drying roughed-out bowls/platters/boxes. Big difference!

    JKJ

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    Quote Originally Posted by John K Jordan View Post
    I have not experimented with using a food dehydrator for drying wood blanks or heard of this from other turners. (I prefer to air dry wood.)

    Maybe describe your blanks. Do you mean you want to dry a complete, unturned blank such as a section of logs? How large? What species? (Some species are more stable than others)
    Or are these blanks cut from logs or rough-turned in a way they can be dried successfully?

    I process and dry a lot of wood. Due to the nature of the structure of wood drying a large solid blank can be tricky.

    JKJ.



    It is 12x12x4 of ambrosia maple. Moisture is 18%. I tried rough turning it and already got a crack. I put it in a bag of shavings from hollowing it out. They completely coated it with heavy wax. I'm guessing covered with wax, it will never dry out?
    Where did I put those band aids?

  7. #7
    Something like that i rough turn to 3/4 inch then coat in anchor seal and let it sit for 4 months or so. 18% is not super wet some fresh cut pieces i turn are in the 30% range. Craft supply sells artisan woodsealer that works just as well as anchor seal but is cheaper. They have free shipping right now until 12/13.

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    Have you considered using a microwave oven?

  9. #9
    I suspect a food dehydrator would dry the outside of your wood too quickly. A large moisture differential between the outside and inside of a piece will often cause cracking. This is the reason why many commercial kiln operators add moisture back to a stack of wood in order to lessen losses due to moisture differential. I think you'd be better off using a small fridge/freezer/dishwasher kiln where you can control moisture loss (by turning down heat or blocking exhaust holes as needed).

    Some other alternatives are first cleaning off any coatings/wax/ and then soaking the piece in DNA (De-Natured Alcohol), Dish Washing Soap, or Boiling Water. If you're in a hurry then a microwave can be used, but you might still need to lessen moisture differential by covering item with saran wrap that's slowly pulled back as the item gets dryer.

  10. #10
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    Quote Originally Posted by Dueane Hicks View Post
    It is 12x12x4 of ambrosia maple. Moisture is 18%. I tried rough turning it and already got a crack. I put it in a bag of shavings from hollowing it out. They completely coated it with heavy wax. I'm guessing covered with wax, it will never dry out?
    Water vapor goes right through wax. A blank waxed all over will still eventually dry out, but slower than unwaxed. It can crack just as much as an unwaxed blank depending on the wood species, and whether pith, juvenile wood, or sap wood is present, how the grain is oriented on the various faces, the temperature/humidity in the environment, etc.

    Waxing the wood properly does slow down the shrinkage which can minimize the cracks. Typically the end grain is coated with wax and the side grain is uncoated. Since water exits the end grain at a much high rate than the side grain, the wood right at the end grain surface can quickly get too dry and shrink too much due to the strong moisture gradient - the cells are literally pulled apart by the strong force of shrinking. Once such a crack/check starts at the surface, it only gets worse. Waxing the end grain slows down the drying at the surface and gives the moisture deep in the wood more time to migrate towards the end grain which creates a less severe moisture gradient and less chance of the strong tangential shrinkage pulling the fibers apart. The thicker the wax the better! When I use Anchorseal I usually decant some into a separate container (a plastic coffee can) and leave it open to the air for a couple of days so it gets thicker and goes on thicker.

    The wood should be sealed as soon as possible after felling the tree or cutting up the log. If you wait until a check or crack already starts, even if it's so small it's invisible, it's too late. Best thing to do with an unwaxed or cracked blank is to cut the crack away then cut thin slices off the end grain until bending one doesn't separate easily. This proves you've cut deep enough. When I process logs into turning blanks I wax the end grain immediately, then check the blank in a few days. If any cracks have developed I cut them away, rewax, and check again after another few days. (Sometimes I end up with a considerably smaller blank but that's far better than a cracked blank!)

    I've successfully dried that size of ambrosia soft maple by waxing just the end grain and air drying on shelves in the back room of my shop which I don't heat as much in the winter. But it depends on the wood - some will crack regardless of what you do, some is better. I have a block of 12x12x15" ambrosia maple drying for about 4 years now with no sign of a crack. On the other hand, I had a 3x3 block of maple split nearly in two! I usually have very little trouble with walnut blanks but recently one 4" thick blank developed a 1/2" deep crack all the way down the sapwood side. I cut this off, rewaxed and the next day it had 1/4" deep crack in the same place. I cut of some more and now the blank is down to about 3" and so far, no cracks. (keeping fingers crossed.)

    When I rough turned bowls, I would always wax the end grain inside and out and sometimes wax the entire roughed bowl. I air dried on wire shelves for several months before finish turning.

    BTW, there are several ways to preserve wet unturned blanks until you are ready to work on them. One is called "ponding" - immerse the blank completely in clear water, weighting it to hold it down. Change the water as needed. Wood will keep indefinitely this way. Another way is to wrap in plastic and freeze it. Another way is to boil it, discussed in detail recently in another thread.

    BTW, I have some blanks that I cut from trees in 2006 and earlier. I try to process some wood every few months so I'll have a continuous supply of dry wood. (I far prefer turning dry wood to green.) I do make some bowl blanks, but mostly blanks for spindles, boxes, and other generally smaller things.

    Freshly cut chunks ready to process, mostly cherry:
    cherry_maple_excavator_hold.jpg

    Directly from the sawmill behind the barn:
    blocks_from_sawmill.jpg sawmill_blanks.jpg

    This guy's ready to go rough out some bowls:
    P2253156s2.jpg

    Processing on shop bandsaw
    ambrosia_maple_IMG_20171202_141342_010.jpg

    Some ambrosia maple ready to put on drying shelves:
    ambrosia_maple_IMG_20171202_175922_594.jpg

    Some drying on wire shelves:
    drying_IMG_5757.jpg dogwood_IMG_5759.jpg

    JKJ

  11. #11
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    From live standing OO tree, ends coated with anchorseal, got home, cut almost a 3" slab from the very base of the tree, microwaved it a long, long time, then sanded it and varnished it.

    I want to strip it, sand the brown down to yellow, then seal it with several coats of Epiphanes. Hopefully I can extend the yellow considerably using their Marine spar varnish.
    Attached Images Attached Images

  12. #12
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    I tried two times at 50% power for 2 minutes each time letting it cool. Got a one inch crack in the side of the bowl.
    Where did I put those band aids?

  13. #13
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    Quote Originally Posted by John K Jordan View Post
    Water vapor goes right through wax. A blank waxed all over will still eventually dry out, but slower than unwaxed. It can crack just as much as an unwaxed blank depending on the wood species, and whether pith, juvenile wood, or sap wood is present, how the grain is oriented on the various faces, the temperature/humidity in the environment, etc.

    Waxing the wood properly does slow down the shrinkage which can minimize the cracks. Typically the end grain is coated with wax and the side grain is uncoated. Since water exits the end grain at a much high rate than the side grain, the wood right at the end grain surface can quickly get too dry and shrink too much due to the strong moisture gradient - the cells are literally pulled apart by the strong force of shrinking. Once such a crack/check starts at the surface, it only gets worse. Waxing the end grain slows down the drying at the surface and gives the moisture deep in the wood more time to migrate towards the end grain which creates a less severe moisture gradient and less chance of the strong tangential shrinkage pulling the fibers apart. The thicker the wax the better! When I use Anchorseal I usually decant some into a separate container (a plastic coffee can) and leave it open to the air for a couple of days so it gets thicker and goes on thicker.

    The wood should be sealed as soon as possible after felling the tree or cutting up the log. If you wait until a check or crack already starts, even if it's so small it's invisible, it's too late. Best thing to do with an unwaxed or cracked blank is to cut the crack away then cut thin slices off the end grain until bending one doesn't separate easily. This proves you've cut deep enough. When I process logs into turning blanks I wax the end grain immediately, then check the blank in a few days. If any cracks have developed I cut them away, rewax, and check again after another few days. (Sometimes I end up with a considerably smaller blank but that's far better than a cracked blank!)

    I've successfully dried that size of ambrosia soft maple by waxing just the end grain and air drying on shelves in the back room of my shop which I don't heat as much in the winter. But it depends on the wood - some will crack regardless of what you do, some is better. I have a block of 12x12x15" ambrosia maple drying for about 4 years now with no sign of a crack. On the other hand, I had a 3x3 block of maple split nearly in two! I usually have very little trouble with walnut blanks but recently one 4" thick blank developed a 1/2" deep crack all the way down the sapwood side. I cut this off, rewaxed and the next day it had 1/4" deep crack in the same place. I cut of some more and now the blank is down to about 3" and so far, no cracks. (keeping fingers crossed.)

    When I rough turned bowls, I would always wax the end grain inside and out and sometimes wax the entire roughed bowl. I air dried on wire shelves for several months before finish turning.

    BTW, there are several ways to preserve wet unturned blanks until you are ready to work on them. One is called "ponding" - immerse the blank completely in clear water, weighting it to hold it down. Change the water as needed. Wood will keep indefinitely this way. Another way is to wrap in plastic and freeze it. Another way is to boil it, discussed in detail recently in another thread.

    BTW, I have some blanks that I cut from trees in 2006 and earlier. I try to process some wood every few months so I'll have a continuous supply of dry wood. (I far prefer turning dry wood to green.) I do make some bowl blanks, but mostly blanks for spindles, boxes, and other generally smaller things.

    Freshly cut chunks ready to process, mostly cherry:
    cherry_maple_excavator_hold.jpg

    Directly from the sawmill behind the barn:
    blocks_from_sawmill.jpg sawmill_blanks.jpg

    This guy's ready to go rough out some bowls:
    P2253156s2.jpg

    Processing on shop bandsaw
    ambrosia_maple_IMG_20171202_141342_010.jpg

    Some ambrosia maple ready to put on drying shelves:
    ambrosia_maple_IMG_20171202_175922_594.jpg

    Some drying on wire shelves:
    drying_IMG_5757.jpg dogwood_IMG_5759.jpg

    JKJ

    Wow, very informative! I wish my health would allow me to get out and find wood, then process it myself! I live in the Olympic mountains and there are wood piles up where they clear cut, then leave the stumps in a giant pile. Mostly fir,hemlock,maple,some cedar.
    Where did I put those band aids?

  14. #14
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    Quote Originally Posted by Dueane Hicks View Post
    I tried two times at 50% power for 2 minutes each time letting it cool. Got a one inch crack in the side of the bowl.
    Not much time in the microwave.
    50% simply means it will run half of the time on full power.
    Might have been the heating and the cooling off caused the crack. If the slab I dried was still very hot after running the micro a couple of minutes, I'd stick it right back in without letting it cool. I knew if it was very hot that it still had high moisture.
    But, perhaps my one and only try with a microwave was "beginner's luck"?
    Last edited by Bill Jobe; 12-14-2019 at 10:30 AM.

  15. #15
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    Seems that the food dehydrator may not be s cost wise investment? They have small cheap ones and large pricey ones. Fridge kiln is the way to go IMO. Just my $0.02.
    I did try the micro, it does work, but don't use "yours". Buy a new one and give that to the wife and use the old one...... I did 1 min and wait a pretty long while to let the wood really cool to ambient. I put the item is an open ziplock with a paper towel to soak up the vapors.

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