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This turned out to be a moisture issue which was discovered and resolved when I brought samples of the wood back to the distributor that sold it to me.

Putting a moisture meter on it we discovered the wood had a moisture content of 12%. Since I control the temperature and humidity of the shop...the man admitted that unit was pretty well fouled up in the drying process. Plus it was hard to argue with the resawn boards I also brought that were cupped like a potato chip. I told him that all the lumber had been processed into 19" billets and had been waxed.

He agreed to replace all 140 board feet at their expense. A very honorable company.

I bought a Wagner MMC205 moisture meter today. It's a little limited in the density range but the density of the sapele and maple I use is well within the range. I also read you can set it for half the density and double the reading...or something lke that. Doesn't really matter. It's probably a good idea to have a moisture meter on hand when sorting through piles of wood. That would haved saved me from this whole debacle.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Nice when people do the right thing!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

That is casehardening....when the resawn wood cups toward the middle of the board. By definition, wood that cups toward the outside is reverse casehardened.
http://fennerschool-associated.anu.edu.au/fpt/drying/kiln.case.html
Casehardening is almost always caused by incomplete or too-fast kiln drying. It's not because your wood was at 12%, but because a very important step was not done. That step is called normalizing or conditioning. The wood is heated through several cycles with sufficient moisture (steam) to relieve the stresses.
In very rare cases, air-dried wood can also suffer from casehardening. I air dry most of the woods I cut, and I cannot recall any problems during resawing, particularly if the wood is several years old. The shop where I dry the wood has no humidity or temperature control, so it sees all the swings in temperature and humidity that it would experience outside. The only difference is that it is not rained on. Through years of using my moisture meter, I have found that it is rare for the wood to drop below 10% MC in that shop. With that in mind, I always bring the wood into my humidity-controlled shop up to a year before using it. Stickering the wood and placing a fan on it will speed up the equilibrium process tremendously.
The pin type moisture meter I use has functioned flawlessly, is very durable, and is much less expensive than the others on the market.
http://www.amazon.com/Comprotec-Canada-19921-Timber-Moisture/dp/B001DDWR72
I have had it for 20 years, and it has been dropped on hard surfaces numerous times.

Basically, you are normalizing the stresses. The main advatage to doing the normalizing before resawing is that it will save a lot of headaches and probably increse the yield.

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John

Interesting post, John.

The company is going to replace the wood and I planned on bringing the new moisture meter I bought with me whe I go to sort through the unit. Unfortunately, it appears that simply measuring the moisture content is not going to reveal an issue of case hardening. I'll have a talk with the manager about this and present him with the text of that link you provided.

Thanks for the explanation. Even after he measured 12% moisture in my samples it still didn't make sense why it cupped in the direction that it did. If the wood was wetter inside it should have cupped opposite. Case hardening completely explains what occurred.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic