Kiln dried and Air dried Lumber

[Weez]

I just wanted to know the expected out come if laminating kiln dried and air dried lumber. I think I know what it might be but just checking. The air dried walnut would be sandwiched between kiln dried birch.

Weez

[Barbara Gill]

To give you a simple, quick answer. The glue joints would probably fail. The shrink swell ratios for the two woods are probably different enough to cause a problem. I have to leave in a sec. so I don't have time to look them up. The moisture situation may or may not influence the outcome. Just because wood has been kiln dried doesn't mean the MC is still low, and just because wood is air dried doesn't mean the MC will be high. Also the thickness of the stock will influence the outcome as will the glue. The book Understanding Wood by Bruce Hoadly is a good reference with which to begin.

Barbara
www.velvitoil.com (http://www.velvitoil.com)

[TDHofstetter (Guest)]

Hi, Weez.

When you say they'll be sandwiched together, do you mean boards laminated edgewise long-grain-to-long-grain, as in a panel or bowl blank? If so, the glueup will probably be OK. Wood moves very little along its length, and if the boards aren't terribly thick they'll move very little across the grain.

If you mean you're laminating them face-to-face in a stack, beware unless you can measure the moisture content and it's pretty close to the same in all the boards involved in the glueup. Otherwise, something's likely to give sooner or later.

Like Barbara says, kiln-dried can sometimes have more moisture content than air-dried. A lot of factors are involved. If all the wood has been laid up in your shop for a long time, it may all have the about same MC.

Forever endeavor.

-- Tim --

[Weez]

I kind of figured that was the answer, but I have seen alot of differnt types of wood glued up so I figured I ask. I actually have the book, I will pull it out and do some more reading. The more I find out the more questions I have. I guess that good.

Weez