Lengthwise shrinkage
October 31, 2013 | 7:00 pm CDT

Q: We are using southern yellow pine for furniture and have been getting what looks like lengthwise shrinkage. However, I was always taught that wood does not shrink along the grain. Can you help please?

A: I also have heard many times that wood does not shrink lengthwise an appreciable amount. But there are several exceptions to this statement.

First, wood around the core of the tree, often called juvenile wood, does indeed shrink lengthwise several percent from green to dry. As a general rule of thumb, consider this shrinkage to occur in the first 15 to 20 annual growth rings from the center of the log.

Second, with softwoods, compression wood will shrink lengthwise several percent during drying. Compression wood is identified by its darker color and by the oval shape of the stem and wide growth rings in the location of the compression wood.

Special note: Hardwoods have juvenile wood and tension wood (not compression wood) that shrinks several percent in drying.

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Gene Wengert

Gene Wengert, “The Wood Doctor” has been training people in efficient use of wood for 45 years. He is extension specialist emeritus at the University of Wisconsin-Madison.