Drying Maple

Discussion in 'Tutorials and Tips' started by glenkey, Jan 15, 2011.

  1. glenkey

    glenkey

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    I have gone out and found some highly figured maple,:D after roughing it out, I need to get it dried so that I can finish it. To date I have been wrapping in newspaper, some I have coated in sealer. I know that the ones coated in sealer will take longer to dry but I want to get them dried as fast as posible.
    Don't have room for the "old freezer kiln" so that is out of the question. Idea's please.
    Thanks to all that are willing to post with help.
     
  2. MichaelMouse

    MichaelMouse

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    Hoping you don't really mean "coated" as in covered with. I have ruined some nice maple that way when I was trying to do as others recommended. Black mildew got in and it looked dirty at some depth, even up to 1/4" inch. When you turn the coating off the maple consider changing the paper on the others for the same reason.

    Figured stuff is the least likely to split, regardless how badly it's handled, but I'd still store it at maybe 60% or more for a couple-three weeks before putting it in a quiet air place in the shop for the next month - or more, depending on thickness.

    If you're going to push them, warm them inside a container to get the molecules moving. Don't go crazy. Hundred, hundred fifty is plenty. When you see some condensation, allow it to sit for a half hour, then slow vent, warm, repeat. After that, leave in that quiet area in the shop. That's the way the kilns really work. Warming and venting as distinct cycles, rather than allowing continuous evaporation. Since the RH in the kiln or the container is high, the surface doesn't check. You can heat from the outside in or the inside out in the micro.
     
  3. glenkey

    glenkey

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    Yeah I painted a coat of sealer on them after roughing out. Guess I should go get that stuff off of the pieces.
    Spent some time out in the shop today and wrapped a couple.
    Only microwave is the wife's, and she says NO way will I be putting wood in it.
    Can't figure her out. The shop is the two car garage with a breezeway that leads into the kitchen. I sweep up the dust and shavings in the breezeway about once a week. :cool2:
     
  4. Barbara Gill

    Barbara Gill

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    I have tried microwave drying and it did not hurt my microwave. You can go to Wal-Mart or SAMs and pick one up for very little.

    Your post may get moved since this forum is for telling not asking.
     
    Last edited: Jan 17, 2011
  5. JeffSmith

    JeffSmith

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    Have you tried boiling. I've gotten in the habit of starting a boiling pot whenever I'm roughing madrone burl or maple burl. rough it out, core it, and throw everything in the pot until I'm done roughing for the day. Turn off the fire, leave the madrone in the water until it's cool. The maple comes out while it's still hot and I let it cool on the shop floor before stacking loosely on wire racks with good ventilation.

    Boiling and removing hot seems to stabilize figured maple and reduce the drying time of the roughed out blanks to about half.
     
  6. john lucas

    john lucas

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    My question on Boiling is how much does it cost to do that. If it cut the drying time down to a week and I was a production turner I could see it but I think drying cabinets would be more economical and would reduce drying time as much or more than boiling. Just asking so I can learn the ins and outs of all the process's.
    Microwaving doesn't hurt the microwave "unless". I've dried quite a few things in the microwave. Mostly box blanks but have done 8 or 10 bowls. The "unless" comes in because I had bowl that had a hidden sap pocket in the wall. As I was gradually increasing the drying times the sap pocket apparently got hot enough to turn to steam, burst through the side of the vessel and caused the wood to get hot enough to ignite. It only burned a 1" patch but it took me 2 months to get the smell out of the microwave. I put baking soda in there and let it sit. Fortunately it is just me at home and I can tolerate bad smells.
     
  7. MichaelMouse

    MichaelMouse

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    Boiling doesn't make things dry faster. If it did, we'd leave the laundry in the washer without spinning before we took it to the dryer.

    Heating the wood to a temperature above the plastic temperature of lignin will help relieve some stress in the wood, or so it seems. If you heat in a vat of water, no energized water can evaporate, while if you heat in a microwave you can saturate the air around the piece, and if you bag it, get condensation on the bag when the heat is no longer applied. It'll dry faster than the same piece at room temperature.

    Couple of points to ponder on microwaves. Electronics HATE moisture. You have the fan running when the power's applied, but most don't use the fan after the heat's off. Recipe for a ruined microwave. That's why you pull the piece after the heat's off. Also why I like to bag, because then I am doing what they do in the kiln, keeping a high RH around the wood so it doesn't surface check and harden.

    Point number two is that insulation can hold heat in as well as exclude it. If you have thick places in the piece, go intermittent, or you risk building the heat inside the insulated space to the point of ignition. I go intermittent - 25-35% "power" - from the outset, and use a longer time myself. Not sure whether a guy could use the built-in humidistat and the reheat setting to good effect. Maybe someday I'll try it.

    Oh yes, the magnetron is either on or off, it doesn't run on intermediate "power" settings. Listen to the fan slow as the heat cycle begins and speed when it ends if you doubt.
     
  8. Greg Thomas

    Greg Thomas

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    drying and wall thickness

    No matter what method, make sure your wall thickness is close top to bottom. If the bottom is thick and the walls are thin, there's a good chance that the rim will crack from uneven drying.
     
  9. MichaelMouse

    MichaelMouse

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    No. Wood loses water through the end grain at a rate 10-15 times the rate of loss through face grain. A bowl MUST dry unevenly, because it can do no other. Look at the presentations on the surface of any rough. Distortion is a product of shrinkage, and is determined in direction by the orientation of the annual rings and in magnitude by the species and rate of growth. This is a percentage shrink, and if the bottom is too broad you have more absolute loss in dimension which can affect the stress on the upper parts to the point of fracture. Five percent of five inches is more than twice as much as five percent of 2, which is a good maximum chord length for a 1 inch thick wall on a 10 inch bowl. Air, of course, does not shrink, so hollowing out changes the game above the bottom entirely.

    Really good information on wood and water in Hoadley's Understanding Wood or the research from which it derives, Wood Handbook, Wood as an Engineering MAterial, available free at the Forest Products Lab site. http://www.fpl.fs.fed.us/products/publications/several_pubs.php?grouping_id=100&header_id=p
     
  10. Greg Thomas

    Greg Thomas

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    how wood dries

    I don't disagree with Michael, wood does not dry evenly and species and grain pattern makes a difference as well as drying conditions. .Uneven drying was a bad word choice on my part.
    In David Ellsworth's book, David describes "A crack in a poplar bowl due to uneven wall thickness-1/4" at the rim and 3/4" at the base. The rim dried out faster than the base, which caused it to lose its elasticity and crack when the base began to dry." He goes into greater detail in the section on "How wood dries".
    My understanding of how a green turned blank dries has evolved and continues to evolve with every new bowl I turn. I probably know more than I can say about specific conditions in my shop just from eperience and intuition gained by that experience. My experience has shown that what I wrote about the danger of cracking due to the base being much thicker than the rim is true, most of the time. I'm always open to a piece of wood teaching me something new.
     
    Last edited: Jan 25, 2011
  11. MichaelMouse

    MichaelMouse

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    Not sure turners trump scientists. It makes little sense to make a green rim thin in any case, because you won't have enough wood to go back to round when it's cured. Most of the slopes I cut tend to lose almost a quarter inch either side of centerline when they cure. http://i35.photobucket.com/albums/d160/GoodOnesGone/Picture-Package-14.jpg

    The "bottoms" of my roughs are often thicker than the bowl is deep, so I certainly cannot endorse that one either. http://i35.photobucket.com/albums/d160/GoodOnesGone/Rough-Life.jpg

    People whose special knowledge lies in working the material are not necessarily the best wood technologists. Sometimes they're not even capable observers.
     
  12. dbonertz

    dbonertz

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    MM

    This statement has been bugging me "Not sure turners trump scientists." I am not sure that scientists trump the experience of a wood turner. To me it is much like an architect does not trump the contractors experience in building something. They both have their experiences one in books and controlled tests and the other as books and practical experience. Both are important and neither trumps the other. Just as drying blanks cannot be done exactly the same in different climates, for the same conditions don't exist in the two seperate states or even homes or shops. Scientist can tell you how wood dries but they do not have the practical experience in drying wood in every different climate, elevation or etc. Sorry for the long response but that remark just got to me.

    Dale
     
  13. john lucas

    john lucas

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    Greg I agree. When I used to leave the base thicker, especially with a larger tenon I almost always lost wood. I started turning so the base +Tenon was the same thickness as the roughed out sides and my losses were reduced to almost none.
     
  14. MichaelMouse

    MichaelMouse

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    If you know how wood dries and why it does what it does but do not take advantage of that knowledge, enjoy the warmth of burning failures. Your statement that experimental data collected over hundreds of thousands of exampless indicates that you have not read the material, nor do you understand that what makes something scientifically valid is repeatability. Had you taken a few moments to read the material referenced, you would know that. They even cover "altitude or etc!"
     
  15. MichaelMouse

    MichaelMouse

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    Yet, as you can see from the examples on my shelf, a base as thick or thicker than the work itself does not affect the piece. Might want to find out what else you did, and pass that along. I have a suggestion. "Larger tenon" means a broader bottom? There's where the problem lies.
     
  16. dbonertz

    dbonertz

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    MM,

    I have read plenty about drying wood. I stand by what I said. A scientist can tell you how wood dries but cannot tell me how to dry wood in my climatic situation unless they study my specific situation. I have dried hundreds of bowl blanks with very little loss. I do this because of trial and error and found what works in my shop and situation (climatic and home). I will take the experience of a turner with a lot of experience over some scientist in his lab any day. The turners experience may not be scientific but they have proven it works in his/her situation.

    If I were to believe every scientific expert then I probably would still believe the earth is flat or eggs are bad for you and etc.:D

    Dale
     
  17. Don Nurmela

    Don Nurmela

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    engineers vs scientist

    This dialog reminds me of the difference between an engineer and a scientist. Both are given the same situation, you are at one end of a football field and on the other end is a beautiful naked blonde. You are to move halfway to the other end with each move continue doing so. The question is will you ever get to the other end and the blonde beauty? The scientist says no, you will never get to the other end. The engineer says close enough for all practical purposes.:)
     
  18. Steve Sloan

    Steve Sloan

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    I'm with Don. Close enough! Can't we all just get along :cool2:
     
  19. dbonertz

    dbonertz

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    That is funny Don and so true. I like that. Made me smile.

    Dale
     
  20. Steve Worcester

    Steve Worcester Admin Emeritus

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    Maybe it is that scientists don't study the same issues that woodturners face?
    Not a lot of data probably on wood in the state we leave it. End grain and side grain.

    To answer the other question, Stephen Russell wrote an article on boiling that I have posted on turningwood.com under "how toos"

    Essentially you need a propane burner , like used for turkey frying and a huge pot and lid. Cut up 55g drums work, or a big pot like used for crawfish boils.
    Bigger takes longer, but you absolutely want to make sure it is inches larger that the largest bowl. You start with he bowls in cold water and do a rolling boil for an hour or so ( per inch? Don't remember) and remove when cool, per Steves instructions

    And I don't agree that boiled bowls don't dry faster. I personally think that they do dry faster because you have loosened up the cells for a more free exchange of water AND softened the fibers to lessen warpage. However, I have no impiricle evidence
     
    Last edited: Feb 7, 2011

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