wood movement

[John Piwaron]

I noticed an odd (to me) thing the other day. I checked the moisture content of some boards I'd brought home and noted that they were pretty dry. I guess they must have left the kiln not too long ago.

Then I checked some boards I had in the shop for a while. Years in fact. And the top of my bench. That's hard maple. All of the wood that's already there has a higher moisture content than these new boards. Huh. But it does explain why they'll move if I were to joint and plane them right away. They're not drying out in my shop, they're getting re-wetted to some degree. :)

[Rod Sheridan]

Yes John, the new boards will expand slightly with increased moisture content.

You should let them come to equilibrium with your shop before you begin to machine them............Regards, Rod.

[John Piwaron]

Yup. What I found to be interesting is how dry they were. I know to leave them to equalize, but I had expected that they'd be drying out, not picking up moisture.

[Myk Rian]

What's the weather been like lately?

[Howard Acheson]

Not surprising and readily explainable. The newly purchased boards may well have recently left the drier. Kilns will generally dry wood to about 4-6 Equilibrium Moisture Content (EMC). Your shop may well be at a higher relative humidity so the wood that you have had for a while has become equalized to the more moist conditions.

Stack and sticker your newly purchased lumber for 3-4 weeks and check it again. It should equalize and end up at the same EMC as the older wood.