Warping, Moisture, and Wood Shape Memory

      Will a piece of wood that was restrained to prevent warping during drying warp later, while in use? Only if the moisture in its environment varies. October 30, 2005

Question
I know and understand that a commercial mill and drying operation would want to create high stacks to keep the lumber flat while drying, and hopefully it will still be flat after milling before the customer buys it.

My question is this; if a given board down in the stack had been dried without restraint and had a tendency to cup or twist, does it retain that memory after drying after the restraint is removed, thus taking its long term memory and cupping and or twisting later?

If the answer is yes as I suspect, would someone like myself who is sawing for themselves as the end user, be better off allowing the wood to take whatever shape it will before milling individual parts? Assuming the board reached EMC both ways restrained or unrestrained.

I sawed some cherry this week that I think is going to behave badly, and I would rather know that the stress was gone before I made expensive parts out of it rather than have an old memory creep in on a finished product.

I have a place in a shed where I can stand on end, and lean the boards against their edges rather than the face. It is all 12/4 thick with a strong block mottled figure.

Forum Responses
(Sawing and Drying Forum)
From contributor W:
As long as the wood is dry when you build it should not move any more then normal and cherry is pretty stable to begin with.



From Gene Wengert, forum technical advisor:
The lumber does have a memory and will warp if the MC changes after drying. However, the MC is usually very small and so the warp is also very small, especially when compared with the large MC change in drying. As stated, if you have the wood dried to a level that is identical to the MC level in use, then warp is not an issue. That is, wood does not warp or change size unless its MC changes.



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