Q. Is it possible to kiln dry freshly sawn, very wide (16 - 18 inch), 1-inch thick white pine lumber with minimal cupping? By minimal I mean, I want to be able to plane the wide boards down to 3/4 or 5/8 after it's dried to 6 percent.

A. Cupping is a natural tendency of the wood. The side of a piece of lumber closest to the bark will shrink a bit more than the other side, causing cup. This difference cannot be well controlled by changes in drying procedures, although slow drying and rewetting partially dried lumber will increase the amount of cup.

The closer the piece is to the center of the tree (closer than about 8 inches is where the cup begins), the more cupping we will see. A piece really close to the center is nearly 100 percent likely to cup. Unfortunately, wide pieces almost always come from near the center of the tree. White pine is a low shrinking species, so cup will not be really large. So, with fast drying (which gets dry fibers on the outside which are twice as strong as wet fibers) will give you the best chance, but your chances of perfectly flat lumber are not really high.

If you rip the piece down the middle and then dry the two pieces and glue them back together, the two matching pieces, minus the small amount of saw kerf can be flat and look as through they are one piece.

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