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Building Wood Table Bumper Floor


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I have an 8' x 40 inch dining table. It is a bookmatched 2 inch thick walnut. It has a terrible cupping problem. Since this picture was taken, I have since got the cupping out. I wet it down and put buckets of sand on top. I also, put a pot of water on a hot plate burner under it. Then I covered it with plastic…...this did the trick!!

But, now what?? How do I keep it from doing it again?

If anyone can give pointers….please let me know.

Thanks,

Bryan
 

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Hi Brian. Get some 2×4's and clamp them to it. You may want to add a few wedges in the middle to cup the board slightly opposite of where it is cupped. Let it dry for a few weeks by standing it on its end with even airflow going on both sides. You also can go ahead and install your apron instead and see it that will correct the problem. I would do the 2×4's first though.
 

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Discussion Starter · #3 ·
Mr jinx..thanks for your help. One thing I did not add is that I have a homemade kiln that works pretty well. I was wondering if I should put it back in the kiln and then strap and weight it down.

My big question is…what is to keep it from cupping again. Is it possible that the wood will dry out further in the kiln…so much so it will not be able to cup again. I'm assuming cupping is due to moisture in the wood??...take all the moisture out and it ill stop moving (significantly that is…)

Bryan
 

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I'm not an expert like these other guys, but I did do this breakfast bar below. So, I can safely say I know more than some and less then others.
Mine had been dry for several years before I planed it.

I have three thoughts.
1. Get it dry, or at least let it acclimate for a few weeks in the space it will be then seal it to stop moisture absorption.

I think if you keep soaking and heating and weighting it the way you described you run the risk of splitting

2. Stop trying to bend the board to your will and plain it after it has cupped.

3…. Removed/edited I thought this was one solid slab.

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The cupping indicates that the wood was not in equilibrium with the environment. It cupped because it was either gaining or losing moisture. Most probably losing moisture. When the wood gets in equilibrium with the environment, it will not cup. Keeping it flat while it dries to equilibrium should do the trick. The equilibrium moisture content in your basement and you dining room are probably not the same. If the basement has higher humidity, you might want to get a dehumidifier.
 

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I am thinking the cupping occurred because one side was sitting on a surface and thus did not lose moisture as fast as the exposed surface. If you want to put it in the kiln, I think still a good idea to clamp it with 2×4's and place it on it's side over some sticker boards so it dries evenly. You will probably face the same problem applying the finish unless you put the finish on the cup side first. Let us know how it turned out as a lot of people face this problem.
 

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It is good practice to never place a table top flat down on a workbench or other flat surface. Air should be able to circulate on all sides of the top to prevent the problem described by mrjinx007.

As a result, the top is the last piece I build on project so that it can be attached soon after it is made to avoid having it sit around for days and bad things happening.
 
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