drying wood in oven or microwave

Discussion in 'Woodturning Discussion Forum' started by Alan Carter, Jan 7, 2010.

  1. Alan Carter

    Alan Carter

    Joined:
    Mar 23, 2009
    Messages:
    37
    Location:
    Lisle, IL
    Home Page:
    I have some questions about drying wood in an oven or microwave. After rough turning and hollowing with walls around 3/4"-1" thick, what's a ballpark time frame for drying it this way, and at what temperature? Does the species or size of the turning (not the wall thickness) matter? Can you go too long and overcook it?

    Jim at Australianburls.com suggested 18-24 hrs at around 170 degrees. Does this seem about right? We have an electric oven so the heat is drier than a gas oven, so does that make a difference?

    How about a microwave. Since it's a kind of sealed environment does the moisture really get pulled out of the wood? Jim suggests several short bursts rather than one long one so as not to potentially burn the wood. Full power or lower? Time frame?

    I have a pinless moisture meter but I'm not sure how accurate it is without having any flat surfaces to set it against. Any thoughts on that?

    Lastly, would a dry rub of herbs and spices be better than basting with olive oil? (Sorry, couldn't resist.)

    Thanks.
     
  2. John Jordan

    John Jordan

    Joined:
    Jun 24, 2008
    Messages:
    283
    Location:
    Cane Ridge (Nashville), TN
    Home Page:
    If you try to dry it in an oven, you odds of success are very poor. If you try to dry it in a microwave, your odds are poor to pretty good if you accept long learning curve. You can search for threads on the microwave, there are lots of them on the different boards. Some are factual, some are speculation. If you are using exotic (expensive) wood, I would avoid both methods.

    Better to keep roughing more while the first dries-you'll soon be far ahead. :D I'm an advocate of the simplest way, letting the wood dry on it's own. Rough turning/returning is a good way to work. Most of the folks who produce a LOT of work this way, simply let them dry with some simple way of sealing the surface, or in a few cases using de-humidifier kilns. (much different than cooking in an oven)

    There's a article on my website that you might find helpful for the basics of this.

    John
     
  3. Dennis Ford

    Dennis Ford

    Joined:
    Nov 16, 2009
    Messages:
    14
    Location:
    Lufkin, Texas
    Home Page:
    I would not dry wood in an oven. The fast drying would likely cause cracks.

    I have used a microwave before, short bursts is the ticket. Get it pretty warm, take it out and let it cool then repeat (several cycles will be needed). Many woods will cause unpleasant odors resulting in an unhappy spouse unless you have a "shop" microwave.
     
  4. n7bsn

    n7bsn

    Joined:
    Oct 29, 2005
    Messages:
    864
    Location:
    wetter washington
    Home Page:
    I'm on the "never use an oven", never had any inclination to try even.

    Now, micro-wave I have and continue to use. Short power cycles (like 1 minute or less) with long cycles between (like 20 minutes) and lots of rest periods (days) between a few cycles. The result is zero failures in any domestic wood I have tried.

    It's not real fast, but you really don't want real fast, you actually just want a little faster then natural.

    I have been looking at building a real kiln (using a dead refer, plus like a 40 watt bulb and fan), but haven't yet.

    TTFN
    Ralph
     
  5. john lucas

    john lucas

    Joined:
    Apr 26, 2004
    Messages:
    5,822
    Location:
    Cookeville TN USA
    I would not use the oven. I have used the microwave but only on thin wood, 3/8" or less. I have not done but a few bowls . I have done boxes and other small pieces and I follow the 1 minute or less and then let it cool completely before going in again. It takes many cycles and can take all day even on the thin ones.
    I do what John Jordan recommends. Just rough out more bowls while these are drying. Within 6 months you'll constantly have dry bowls to work on. From then on it's just a cycle of rough out a few and finish turn a few. If I need one quick I just turn it thin. It will dry in a few days if it's thin.
     
  6. Tony Latham

    Tony Latham

    Joined:
    Apr 21, 2009
    Messages:
    56
    The microwave will dry it out. If you let it run long enough it will get so dry and so hot that it will start smoking and it'll scare the cr@p outa ya!!!!:cool2:

    Trust me on this....

    TL
     
  7. MichaelMouse

    MichaelMouse

    Joined:
    May 16, 2005
    Messages:
    3,540
    What keeps things from cracking is a relatively small moisture gradient interior to exterior. Makes it vital to control relative humidity, especially in a conventional oven. The micro agitates all the molecules simultaneously, so the insulated interior warms and keeps putting out moisture to the exterior, rather the opposite of conventional ovens. Until it's pretty dry, then it lights off. One inch is too thick, in my experience, for micro drying, and for that reason. I use the so-called lower power settings and longer times than others, but it's pretty much the same thing. Magnetrons don't operate at half output, so, as your fan will tell you, they go on for a short burst, go off to allow equalization, then on again, and so forth. The fan can kill you. Bag your piece. NEVER MICROWAVE ELM and make sure you're not using SWMBO's micro.

    Kiln operators, working with sort of conventional ovens, monitor the relative humidity closely. I don't think you could do anything approximate in an oven.
     
  8. pfduffy

    pfduffy

    Joined:
    Apr 27, 2004
    Messages:
    174
    Location:
    Williamsburg, VA
    drying bowls

    Have you tried boiling the bowls? I am a strong advocate of the process and have experienced excellent results. Put the bowl in boiling water for 1 hr/inch of thickness, let it cool an hour then wrap it in newspaper and stick it in a bag for a couple weeks. Speeds up the process about 50% in time. Microwave works well for thin bowls. Just keep it in a bag, keep the power below nr. 5, and do multiple cycles over a couple hours with lots of cooling time. Start the cycles the next morning and add seconds and increase the power to nr. 6. Keep track of the weight and stop the process when the curve levels out. Phil
     
  9. Jerry Rhoads

    Jerry Rhoads

    Joined:
    Dec 5, 2006
    Messages:
    109
    Location:
    St. Joseph, IL
    A few years ago.
    I just had to give it a trial, in an oven. The lowest setting in the oven was 170 degrees. Every thing more than 1/2' cracked in less thn 45 minutes. It was too fast.

    In the microwave (many cycles on defrost) 1/2 to 1 hour between, any thing over 5/8" is hit and miss on cracking. Up to 3/8", almost always successful. (Sept when I hit wrong button, Makes shop stink.
    I am lucky to have a micro wave in the shop. Thanks to being around when an office was being remodeled.

    People have told me of their success with a box heated with light bulbs.
    Old dishwashers and fridges work for this, or styrofoam on plywood.
    They use more than one bulb and raise the temperture every few days or so.
    I have not had a chance to try this. But hope to soon.

    Jerry
     
  10. Barry Elder

    Barry Elder

    Joined:
    Jun 23, 2006
    Messages:
    184
    Location:
    Fort Pierce, Florida
    Back in the day, I googled "microwave drying for wood" and found 3 very useful articles by woodturners that I found to be very accurate. Remember, wood burns quickly after drying! DAMHIKT!;)
     
  11. hockenbery

    hockenbery AAW Advisor Staff Member

    Joined:
    Apr 27, 2004
    Messages:
    4,304
    Location:
    Lakeland, Florida
    Home Page:
    I experimented with the oven to force cracks.

    My process was to bring the oven to 400 tun it off put the wet Piece from the lathe in the oven leave until the oven totally cools.

    this drys and cracks the wood. some pieces would crack in a way that I found pleasing but too many of them just looked bad.
    My idea was to create "pottery forms from the dig"

    oh well it is only wood

    Happy turning
    Al
     
  12. Gary Slater

    Gary Slater

    Joined:
    Nov 26, 2008
    Messages:
    39
    My question is: at what stage of the turning do you microwave? Rough turn down to your 3/8 then dry? Finish turn then dry? What is your process and do you have a reference? Thanks, Jerry.
     
  13. Thomas Daluisio

    Thomas Daluisio

    Joined:
    Jun 13, 2009
    Messages:
    3
    Location:
    Gloucester Va
    Home Page:
    drying wood

    I have tried the converted "fridge" the "three bag" "dish soap" and I like the stove best of all....I had to go on line to the stove manufacture to find out how to disable the stoves 12 hour safety cycle.

    Normally the newer stoves will shut off in 12 hours, you can change that so it will run until you shut it off.
    I jam it full of things to dry so I cut down on the wasting the electricity, Usually let it run for 36 hours and never had a problem with too much cracking or moving, most are burls that I use..good luck
     
  14. John Jordan

    John Jordan

    Joined:
    Jun 24, 2008
    Messages:
    283
    Location:
    Cane Ridge (Nashville), TN
    Home Page:
    One can complicate a simple and natural process as much as they like, the time is usually better spent turning or carving. :)

    John
     
  15. robert davis

    robert davis

    Joined:
    May 30, 2004
    Messages:
    236
    Location:
    prairie village. kansas
    i have dried wet turnings in microwave for ten years rarely have a problem..weigh piece..set microwave on lowest setting..wrap piece in large towel. run for ten min. remove ,leave in towel until fairly cool. weigh piece. wrap in another dry towel. repeat process until piece does not lose weight.. i am talking about a finished turning
     
    Last edited: Jan 8, 2010
  16. Hugh

    Hugh

    Joined:
    May 6, 2004
    Messages:
    457
    There is something sticking up in my brain right now. A story about someone using a microwave to dry a roughed out bowl and it catching fire and burning at least part of the shop? I could be wrong, but I think I read about it some where.

    I boil Madrone wood as it is the only way I can get a bowl out of it. But I like air dry. Rough out a bunch of bowls and stack them up. If you need something to turn - go find another tree. A little while later you will have so many roughed out bowl you will not need to speed up the process except to clean up the shop from all the roughed out bowls.

    Hugh
     
  17. jffink

    jffink

    Joined:
    Apr 18, 2006
    Messages:
    39
    Boiling, soap-soaking, and heating in ovens and microwaves are fine if your lathe is in your kitchen. Mine isn’t, and I’m sure I’d be in trouble if I tried using the kitchen appliances for woodturning purposes. My woodturning shop is in my basement adjacent to the laundry area, and, after thinking about the aforementioned kitchen methods, I’ve developed a new combination bowl blank treating and drying regimen:

    Rough turn to a wall thickness somewhere between 10% and 50% of the bowl’s diameter, depending on how energetic I feel.
    When I’ve accumulated several roughouts, carefully place them and my turning smock in the washing machine (I use a front loader — top loaders get out of balance too easily).
    Wash using the really hot sanitary cycle with lots of Costco brand green laundry detergent (I think that’s what Ron Kent uses). Add bleach or dye now too if going for such effects.
    When the washing machine’s little “your clothes/bowls are clean and I’m shutting down†tune plays, transfer the “treated blanks†(and smock) from the washer to the dryer.
    Tumble dry on low using about two boxes of Bounce fabric softener tissues (or the Costco equivalent if trying to either cut costs or stay true to RK).
    I figure that the automatic drying sensor should tell me when the bowl blanks are dry.
    Remove from dryer and finish turning the blanks.

    I haven’t gotten around to trying this yet, as I didn’t buy extended warranties for the laundry appliances. But, in the spirit of sharing that all turners are known to have, I’m throwing this method into the public domain for others to try. Let me know how it works. If your spouse is particularly possessive/conservative about the use of the laundry appliances, you might need to pick up a spare pair to devote to your shop. For people with limited space, or who only turn small bowls, one of those stacking washer/dryer combo units might work well — just a thought.

    Happy turning.

    John
     
  18. Rick M

    Rick M

    Joined:
    Mar 11, 2009
    Messages:
    180
    If you wanna boil but keep your activities out of the kitchen, maybe one of these is what you need :D.
     

    Attached Files:

  19. n7bsn

    n7bsn

    Joined:
    Oct 29, 2005
    Messages:
    864
    Location:
    wetter washington
    Home Page:

    It's what I use to boil... Best to time buy one is after Thanksgiving, amazing how cheap they are then
     
  20. Gary Slater

    Gary Slater

    Joined:
    Nov 26, 2008
    Messages:
    39
    Robert, I just want to clarify this. When you say "finished turning" do you mean completely down to the finished thickness? You still have to return your piece to the lathe for sanding, right? Can pieces be finished immediately? Do you have a reference we can go to to see the process or would you be willing to post a more detailed outline of how you do it? Thanks for your time.
     

Share This Page