drying wood in oven or microwave

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

  1. hockenbery

    hockenbery AAW Advisor Staff Member

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    Do the arithmetic.
    I can rough out 2-3 bowls in an hour (I''m slow by professional standards) if I core them I'll have 6 bowls.
    Every hour spent boiling, soaping, microwaving..... is 6 less bowls.

    No one can rough efficiently when they start out. If it takes you 2 hours to rough out a bowl now, you won't get more proficient unless you turn.

    happy turning,
    al
     
  2. Alan Carter

    Alan Carter

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    Thanks for all the responses. So many opinions. A thread on another forum suggested the following: Weigh and nuke the rough turning for 1 min. at defrost. Let cool out of microwave for 1/2 hr. Repeat 3 times and weigh again. Repeat process until weight doesn't change.

    I'm trying that right now so we'll see. If I set a timer I don't really lose much shop time and if I do it while watching TV, no loss at all.

    I know, I know, if I would just be patient, I wouldn't have to mess with all this to begin with. BUT I'M NOT!!!! So there.

    Another small caviat. I don't do production turning, focusing more on sculptural type pieces, so I don't build up a big stockpile of rough turnings. Hence the desire to move along more quickly as I work out the designs.
     
  3. Gary Slater

    Gary Slater

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    I am with you Alan. I have a stock of turning blanks but not lots of time to rough turn then wait. When I want to turn something, it usually means I need it sooner, not later like six months from now.

    Besides, that I don't understand one thing. If the general rule for drying wood is based on a formula of one year of time per one inch of wood thickness plus 1, then how do we expect a bowl blank that may be approximately 3/4 - 1 inch thick, to dry in only six months after applying anchorseal?

    I am ready to try microwaving.
     
  4. john lucas

    john lucas

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    We all go through the gotta have it now syndrome. I did. that's when I did my experimenting with the microwave. I did but one bowl, I got involved in other things and left it too long. It only smoked it but it took months for the smoke smell to go away. I also ruined a bowl once. There was apparently a hidden sap pocket in the wall. It blew a hole in the side of the piece and the steam burned the outer wall of the piece.
    I have looked at the other various means of drying something faster. It all seemed like too much trouble or added to the expense.
    I finally decided John Jordan had it right and now I just turn and let them dry.
    The hardest part for me is that I start on a piece of wood and want to finish it while it's fresh in my mind. I guess that's why all the various hurry up and dry methods come into play. I'm trying to get over that because as Al said, I'd rather be turning or carving than sitting in the kitchen waiting for the microwave to go off.
     
  5. MichaelMouse

    MichaelMouse

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    That will give you an overdried piece which will have to rehydrate to regain equilibrium with the environment. Not what I'm after when I micro. Thus the use of the perforated plastic bag. When a cycle produces only a haze in the bag - done. You can safely use longer times on that defrost or low "power" setting, because it will allow the piece to equalize between powered cycles.

    Microwaving risks waterspotting as well, so it may make an ugly when all you wanted was a dry.
     
  6. odie

    odie

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    Other than the shortened time element, is there any advantage to using ovens/microwaves for seasoning of roughed bowls?

    ooc
     
  7. John Jordan

    John Jordan AAW Advisor

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    One last comment. You don't have to rough turn and return. I've made a living turning green wood for 25 years, I don't rough and re-turn. The pieces aren't cracked, or strangely distorted.

    What I'm trying to get across is if one takes a little time to learn about the material, most of this will come easily. People put a lot of time effort into fighting or forcing the wood instead of working with it.:)

    John
     
  8. Robert Manning

    Robert Manning member

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    Accelerated drying

    I have used some tropical ash that can be rough turned and set on a shelf with no sealer or bag and it will not crack, but that doesn't mean other woods will dry as easily. Some woods, like snakewood, are extremely difficult to dry and are usually found in very thin pieces. Ebony is not as difficult as some woods, but I still would not be willing to put any in a microwave or oven. I also recommend that you are very careful with the microwave as you can ignite the wood and also get burned by superheated steam ejecting out. Microwaves don't heat things evenly, either. What the microwave is great for, is shrinking small dowels that are oversize in a few seconds. Again, be careful as you don't want to damage the wood and weaken your joint.

    I recently dried some hollow forms by wrapping them in a plastic grocery bag. I trimmed the bag so it would tuck into the hollow form opening about one inch. I then took a piece of heavy paper, rolled it into a tube, and inserted it into the opening to hold the plastic bag open. This created a conduit the size of the opening for the vessel to freely exchange air from its center without the rim or exterior drying out. I successfully dried three pieces like this which contained the pith and experienced no cracking. They dried in four to eight weeks which is very reasonable.

    I have also experimented with anchor seal by leaving portions of face grain uncoated and totally sealing end grain areas. I have experienced some success here and will continue with this technique.

    I also tried soaking many different blanks in a 50/50 soap/water solution. The tropical ash worked well, but as mentioned, it was unnecessary. Some wood still cracked. This technique had the feel of a wild goose chase and I doubt I will pursue it any further.

    For the segmented work I do, I require wood that has reached its equilibrium moisture content before I start a project. Some exotics like ebony are rarely available kiln dried and take a very long time to air dry. This is why the vacuum kiln is so attractive to me. Who wants to wait a year for a piece of wood to dry once an idea hatches?

    There is definitely an optimum speed that each piece of wood can be dried, and with show deadlines and other demands, I think accelerated drying can be a valuable process.
     
  9. Wayne Jolly

    Wayne Jolly

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    I would just like to add my $.02 worth regarding using a microwave oven. DO NOT USE ONE IN THE HOUSE! I had a small piece of Aspen that I wanted to experiment with. As I was going into the kitchen to nuke this piece my wife asked me to help her. So I put my piece in the microwave, set the timer for 30 seconds, hit start and went to help her. A short time later, smoke is POURING out of the microwave oven and filling the entire kitchen with smoke which then spread throughout the whole house. Thick smoke. I had accidentally set the timer for 300 seconds instead of 30. Burned that piece of wood to hell and back. When I took my Aspen out, parts of it were more like Ash. Literally. The worst part was the odors left behind. We tried several things to try and get the odors out of the microwave but nothing seemed to work. It took at least two or three weeks for it to go away.

    Xeddog
     
  10. Joe Greiner

    Joe Greiner

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    Here's a list of US patent numbers I've collected on wood drying:
    2387595
    3811200
    4466198
    4620373
    5852880
    6634118

    Google patents ( http://www.google.com/patents ) has most patent documents in single file PDFs, simpler than the documents at the patent office. Although the patent office ( http://patft.uspto.gov/ ) has a more robust field-selectable search engine.

    Low-intensity commercial use may be under the radar; if in doubt about infringement, consult an attorney.
     
  11. David Somers

    David Somers

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    I almost feel guilty throwing in yet another option, but here goes.

    I have to agree with John Jordon that turning from Green straight to finish is a really nice way to work, or rough turning and letting things set for 6 months to a year works very well too. Given a small shop with not a lot of space though I understand peoples reluctance to do this.

    I lived in HI for 10 years (and am now splitting my time between Seattle and HI). The folks out there who make their living turning Koa used to do the "rough turn and let it dry" technique. At any given time they had about a years worth of roughed pieces sitting on shelves that ran around their shops. It was pretty stunning to go in there and see this massive number of bowls waiting to be done.

    Unfortunately, during that drying time they would lose a significant portion of their drying stock to cracking. They were purchasing their Koa trees and paid big bucks for it, especially the curly so this hurt their margins alot. Plus, they would invariably have bowls returned from Arizona and other dry states when tourists would take their big dollar bowls home. Another consequence of having such a large stock of drying pieces was earthquakes. Hawaii has them all the time and a good one could do in the better part of a years work as your pieces tumbled to the floor. They tried lots of things to get around this problem. They tried the various techniques with Denatured Alcohol, soap soaking, drying racks, PEG, etc. Nothing worked or was worth the expense and bother. These are production turners after all and they make their money on volume as well as quality. (these are high dollar bowls made from the Koa and sold to tourists in galleries)

    A number of years ago they discovered a product called Cedar Treat. Also known as woodturners choice. Can be found at www.cedarcide.com. It is a cedar oil product with a carrier from Dow chemicals. (better living through chemistry!) It is rated safe for food contact. Runs about $40 to $45 a gallon and a gallon will do a lot of pieces. A lot!

    To use you rough your piece.....of if you are turning straight from green to finish you would put it on after you are done turning but before sanding and finishing. A windex style spray bottle is a good applicator, or a brush. Apply it over the bucket and let the extra drip back into the bucket. Small pieces can be dipped.

    For Koa they let it set after that for 3 days or so. For other woods they let it sit for upwards of two weeks. At that time the Cedar Treat has converted the water in the cells of the wood to a stable gel. They then apply their finish and the piece is done. They lose almost nothing to cracking now, even for pieces taken back to the mainland to dry climates. They dont need to have a years worth of roughed pieces on hand drying in order to conduct business.

    The cedar smell dissipates after the product is done converting the water. It imparts no taste to food served in the bowl. It doesnt affect the finish whether it is an oil or a shell type finish. It doesnt seep out of the wood over time like PEG can. It doesnt change the color of the wood. Pretty good stuff.

    Although I am not a production turner I use it because I like playing with woods that have a tendency to crack when turned or dried. Macadamia Nut and Ohia are good examples. I also use it because I dont have large amounts of space to support lots of drying roughed out bowls while I continue turning other things. I have been very please with it.

    The company will send you a sample if you contact them.

    Hope this gives you another good alternative for dealing with this issue. In all serious though, consider building up a stock of drying roughed bowls or turning straight from green to finish if you can. Or at least keep that in the back of your mind after you have played with other methods for a while.

    Happy turning!

    Dave
     
  12. David Somers

    David Somers

    Joined:
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    Location:
    Ballard (Seattle) WA and Volcano, Hawaii....on top
    I almost feel guilty throwing in yet another option, but here goes.

    I have to agree with John Jordon that turning from Green straight to finish is a really nice way to work, or rough turning and letting things set for 6 months to a year works very well too. Given a small shop with not a lot of space though I understand peoples reluctance to do this.

    I lived in HI for 10 years (and am now splitting my time between Seattle and HI). The folks out there who make their living turning Koa used to do the "rough turn and let it dry" technique. At any given time they had about a years worth of roughed pieces sitting on shelves that ran around their shops. It was pretty stunning to go in there and see this massive number of bowls waiting to be done.

    Unfortunately, during that drying time they would lose a significant portion of their drying stock to cracking. They were purchasing their Koa trees and paid big bucks for them, especially the curly, so this hurt their margins a lot. Plus, they would invariably have bowls returned from Arizona and other dry states when tourists would take their big dollar bowls home. Another consequence of having such a large stock of drying pieces was damage from earthquakes. Hawaii has them all the time and a good one could do in the better part of a years work as your pieces tumbled to the floor. They tried lots of things to get around this problem. They tried the various techniques with Denatured Alcohol, soap soaking, drying racks, PEG, etc. Nothing worked or was worth the expense and bother. These are production turners after all and they make their money on volume as well as quality. (these are high dollar bowls made from the Koa and sold to tourists in galleries)

    A number of years ago they discovered a product called Cedar Treat. Also known as woodturners choice. Can be found at www.cedarcide.com. It is a cedar oil product with a carrier from Dow chemicals. (better living through chemistry!) It is rated safe for food contact. Runs about $40 to $45 a gallon and a gallon will do a lot of pieces. A lot!

    To use you rough your piece.....of if you are turning straight from green to finish you would put it on after you are done turning but before sanding and finishing. A windex style spray bottle is a good applicator, or a brush. Apply it over the bucket and let the extra drip back into the bucket. Small pieces can be dipped.

    For Koa they let it set after that for 3 days or so. For other woods they let it sit for upwards of two weeks. At that time the Cedar Treat has converted the water in the cells of the wood to a stable gel. They then apply their finish and the piece is done. They lose almost nothing to cracking now, even for pieces taken back to the mainland to dry climates. They dont need to have a years worth of roughed pieces on hand drying in order to conduct business.

    The cedar smell dissipates after the product is done converting the water. It imparts no taste to food served in the bowl. It doesnt affect the finish whether it is an oil or a shell type finish. It doesnt seep out of the wood over time like PEG can. It doesnt change the color of the wood. Pretty good stuff.

    The older formulations used to kill boring insects like termites and powder post beetles but I understand the latest formulation does not. I still have lots of the older formula though so I haven't experienced this. Boring insects are a big problem in HI so I am not sure how this will affect everyone.

    Although I am not a production turner I use it because I like playing with woods that have a tendency to crack when turned or dried. Macadamia Nut and Ohia are good examples. I also use it because I dont have large amounts of space to support lots of drying roughed out bowls while I continue turning other things. I have been very pleased with it.

    The company will send you a sample if you contact them.

    Hope this gives you another good alternative for dealing with this issue. In all seriousness though, consider building up a stock of drying roughed bowls or turning straight from green to finish if you can. Or at least keep that in the back of your mind after you have played with other methods for a while.

    Happy turning!

    Dave
     

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