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Northern Hardwoods, Part 1
Many of our customers do not understand the difference between the true heartwood and discolored wood of these species. Some believe that "brown" maple and "red" birch are actual species. I would like to briefly explain what is going on in the heartwood and in the next issue of Splendid Splinters go into more detail about the various stages of discoloration and decay of northern hardwoods.
If you were to take a cross section of a PERFECT northern hardwood tree, you would find a pencil sized pith surrounded by 100% white, unblemished wood. However, such a stem is rare. A myriad of injuries can happen throughout a tree's life which include insect or bird damage, broken branches, trees falling into one another and gouging themselves, mechanical wounds from logging, fire damage, etc. As a result of these wounds, the wood becomes exposed to air and moisture. A process of discoloration begins which travels up and down the stem affecting the wood. This can go on for 40 - 50 years or can stop at any time.
However, when new growth is created it forms a barrier from the discoloration process. This wood and future new wood will be white and not affected by stain until possible future injury. That is why if you look at the various log ends of a northern hardwood log or firewood pile, you will see different sized and shaped "hearts" (discolored wood).
The discoloration process should not be confused with the TRUE dark colored heartwoods of other species like black cherry, butternut and black walnut, the hickories, the oaks, etc. The darker heartwoods vs. the creamy or white sapwoods are the result of chemical change that occurs in the aging process in the wood cells. This is a natural process which is totally different from the northern hardwoods where the dark wood is the result of the discoloration process initiated by injury.
© 2001 by David Mather. All rights reserved. No parts of this publication may be reproduced in any form or by any means without the written permission of the author.