WWA Info Exchange

I recently built a top 24" x 40" using Ash. Had the wood laying in the shop and knew it wasn't completely dry. (Was 14 to 16%) Turned out beautiful and after laying around the shop for about 10 days started to put finish on it. That's when I noticed it had started to cup! No way to pull that thing flat on a cabinet!

Since this top is 1 1/2" thick I didn't expect it to move much. I've been told to lay it out where air can get to both sides and that it will probably flatten out. Don't know if that's true but am concerned that it will later (after assembly) start to cup again.

Decided to start over and went to my wood supplier to get Hard Maple. Put a moisture meter on the Maple and found it to have about 12 to 14%. Now I fear I'm headed for the same problem.

So after a long story I thought I'd ask what needs to be considered to assure a good stable top? Anyone having experience to share that will help me avoid another problem will be appreciated.

Thanks, Woodshoplast

Unless it's quartersawn, there's really not much you can do long term other than finishing both sides with several coats of whatever you prefer, and that only slows the seasonal changes, but doesn't stop them completely. The problem with flatsawn is that it's flatsawn, and wants to cup towards what was the center of the tree. If that's all you have available, I'd advise putting the cup side down, or if you are doing a top several boards wide, alternate cup up, cup down.

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If it's really a butcher block, it's about as stable as you'll get. End grain at 1 1/2" should equalize top/bottom pretty fast. You were properly informed to keep both sides in open air. If it's really a flat grain piece, other factors come into play, but it's still the proper thing to do.

The only reason 12-14% moisture would make a difference is if it's now much less or more. The content referenced equates to a 70% relative humidity. If you live near the coast, you may never get much below without heating or air. If you do either regularly, you want to keep the wood stickered in those conditions for 3-4 months. End grain shouldn't matter.