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| Dehydration http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=15402 |
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| Author: | Zach Ehley [ Wed Jan 16, 2008 11:51 am ] |
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So I get home and once again I realize that I forgot to take the humidifier reservior back down to the shop this morning before I left for work. The RH dropped to 24% during the day and naturally the three test tops (joined but not braced) I had in there are cupped like potato chips. Thats shoots my nights plans on working in there, but got me to thinking. What determines which direction the top will curl? I assume it has to do with the quatering of the top. When deciding which side is the inside and which is the outside, does this come into play? Is it better for the wood to want to flatted out the top, or bubble it up more? I assume the bracing grain also plays into this. |
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| Author: | Zach Ehley [ Wed Jan 16, 2008 11:54 am ] |
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This may have been a dumb question, but maybe not. All tops curled up and were flat on the work bench with nothing under them. It may be the top surface is exposed to the dry air and contracted first, but why wouldnt it even out once it curls up and the bottom is exposed????? 
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| Author: | Jody [ Wed Jan 16, 2008 12:30 pm ] |
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I know it does have to do with the direction of the grain , and one exposed side could be affected more, initialy, during changes in humidity . I think the problem with your train of thought though is with quartered wood , that is split and opened like the pages of a book ,I believe you are "reversing" the grain . that is to say if the tendency for the unsplit top would be for it to raise up in the middle ,due to grain orientation .when you "flip" them open , the top now becomes the botton of the other half and it would tend to have a reverse cup .. anyways thats my understanding of it .. Jody |
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| Author: | crazymanmichael [ Wed Jan 16, 2008 1:17 pm ] |
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zach, you hit the reason on the head ; the exposed side gives off moisture and shrinks, thus the upward curl. |
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| Author: | BTucker [ Wed Jan 16, 2008 1:36 pm ] |
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flip the top over and you can watch it go back to flat, then curl upwards again. |
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