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Thread: DNA Drying Troubles

  1. #1
    Join Date
    Feb 2012
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    Upstate SC
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    DNA Drying Troubles

    I started using denatured alcohol to help speed up my bowl drying back at the beginning of the summer. I have dried approx. 50 bowls from 8" to 12" of maple and black cherry and have had probably 95% or better success rate. They are from 8-10% moisture in about 6 weeks. I turned about 20 walnut bowls about 6 weeks ago and unwrapped them tonight and about 15 of them had huge cracks in them. My process: rough out to about 1", soak for 4 hrs, flash dry, and wrap in 2 layers of newspaper and place on the shelf. I was wondering if the alcohol just " wore out"? I started with 5 gallons and over the course of the summer probably added another 4 gallons due to loss or evaporation. What do you guys think? Thanks, Michael

  2. #2
    Micheal, I don't have much experience with DNA, but, from what I've read and learned about it makes me think that your not soaking your rough turned bowls for a long enough period.
    Len

  3. #3
    Micheal, you need to soak them for 24 hours. You can do it for longer but it won't really make any difference. I usually do mine to final thickness and have pretty good luck with them not checking. They will warp a little. But, it does add a little artistic flare. I also don't wrap them but just put them in a brown paper bag and staple shut.

    A question for you--What do you mean by "flash dry?"

  4. #4
    Join Date
    Feb 2012
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    Upstate SC
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    By flash dry I mean just let the surface dry for a few minutes before wrapping. I should have said I soaked for a minimum of 4 hrs, some were overnight. The maple and cherry were fine, just the walnut cracked. All were fresh cut trees and turned within a few days of harvesting.

  5. #5
    I always soak for a minimum of 24 hours, except for fruit woods and they get 2-3 days in the alcohol. Fresh cut walnut is a very wet wood and will take forever to dry naturally, so it would stand to reason that the alcohol / water replacement would take longer in the "soak".
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    No, it's not thin enough yet.
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  6. #6
    Join Date
    Oct 2006
    Location
    Harvey, Michigan
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    Michael - I had the same problem when I first started using DNA. I used to soak wet maple rough outs for 4 hours and a lost bunch of them. Found that by soaking at least 24 hours (or lots longer) that my success rate went up dramatically. Found that you if you don't soak long enough, there will be problems but that you can leave a form in the DNA for days and not cause any problems.
    Last edited by Steve Schlumpf; 10-03-2014 at 11:45 PM.
    Steve

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  7. #7
    Join Date
    Apr 2006
    Location
    Sioux Falls, SD
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    What Scott said, I don't get a lot of time in the shop anymore so there are times they will be in the DNA for a week or more and it seems to not make a difference as long as it is 48hrs or more.
    Wally

  8. #8
    Join Date
    Oct 2006
    Location
    Manistique, Michigan
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    I soak in Denatured alcohol for at least 48 hours, flash for an hour and place in grocery store bags (craft paper if you know the paper industry). I do not leave a direct opening for air exchange. I use the bag as an equal humidity chamber and let the exchange take place through the bag. I do mostly maple and cherry, some walnut. However, soft maple has been the most popular lately. I do get some cracks, but they are easily filed with instant coffee laced epoxy.
    Thank you,

    Rich Aldrich

    65 miles SE of Steve Schlumpf.

    "To a pessimist, the glass is half empty; to an optimist, the glass is half full; to an engineer, the glass is twice as big as it needs to be." Unknown author



  9. #9
    Join Date
    Mar 2007
    Location
    Rochester, NY
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    365
    I've used DNA a few times but stopped partly because I think it is pretty expensive. I can't really comment on its effectiveness but I can comment about the chemistry that is involved. DNA soaking essentially allows alcohol to move into the wood and mix with the water that is naturally present. If the soaking period is long enough then all of the water in the wood is diluted with alcohol. The water from the wood moves out into the alcohol and dilutes it. You could use a hydrometer to track this dilution. The alcohol that we can purchase has a small amount of water already in it and a poison to make is denatured so we won't drink it. This means that it starts out at about 98% alcohol or 196 proof. I have read that once the the alcohol is down to 60% (120 proof) the DNA looses its effectiveness. Adding more fresh alcohol will extend your solution's usefulness but it will have the most effectiveness only when it's fresh.

    Cheers,
    David

  10. #10
    Join Date
    Feb 2008
    Location
    Cullowhee N.C.
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    I don't use DNA, just put my bowls in brown paper bags and set them back for 9 months to a year. Haven't lost one to cracking in several years. I have roughed out a few that already had checks in them that I had to turn much smaller to remove any checks in the rough out. The key to drying out rough bowls with out cracks are, (1) make sure that there are not any checks in the wood before drying starts. If there are any small checks the rough out they will only get larger as the wood dries. (2) turn the bowl of form to a consistent thichness with the bottom just a bit thinner than the rest of the bowl. This allows it to move during drying. (3) try to turn bowls and forms from sections of the tree that have no pith in them or near them if possible. (4) If I have a spot like where I limb comes through the rough out, I soak it with thin CA before the rough out is placed into the bag and check it about a week later and soak it again with thin CA if there seems to be a problem. This CA doesn't show up after the piece is returned and sanded down. As far as DNA soaking goes I tried it years ago and didn't like it. I'm just not in that big of a rush and can't seem to find the time to return the dried rough out's I have on hand anyway. I don't know of any big name turners that us it, They either just wait or put their rough outs into a kiln to dry. Having a 10 to 20 gallon container of very flammable liquid setting in my shop just doesn't appeal to me. I feel that any thing one does to speed up the drying process increases the chance of losing pieces due to cracks, and any thing that can slow down the process of drying like placing them in paper bags reduces the risk of cracks occurring.
    Jack

  11. #11
    Join Date
    Feb 2012
    Location
    Upstate SC
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    Thanks everyone for their input/suggestions. I will try soaking for longer periods of time. I also wonder how many bowls you can soak before the alcohol is too diluted with H20 to work. I thought of buying a hydrometer and comparing the used to the new alcohol and seeing how big of a difference there is. Thanks again.

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