Date: 2010-06-01
Gene Wengert
Q. We bought some 8/4 cherry lumber that had been sprayed before drying with commercial end coating. After drying, we trimmed off the ends as we began to use the lumber and we noted some of the lumber had fairly severe honeycomb (internal cracks) at the end (the last 12 inches or less) while other pieces were perfect. All of the bad pieces were bad on one end and fine on the other. What are the cause's of honeycomb? Could the end coating contribute to this problem? Is there a different drying schedule for end coated lumber? Could KD lumber that is at room temperature develop honeycomb by being out in 10 degree weather?
A. Honeycomb at the end of a piece of lumber is most often associated with normal end checking that went deeper into the piece of lumber. This honeycomb will occur with end coated lumber when the end coating was applied after the ends had already started to dry and had already begun to check or crack. In this case, however, we would see the honeycomb on both ends.
When honeycomb is on one end only, then it is nearly certain that you had some bacterially infected wood (no danger to humans), and this bacteria weakens the wood cell structure. The bacteria enters the living tree (and does it damage in the living tree) through the roots, moving up the stem about 1 inch per year, so it is often found only on the butt end of the log and therefore the butt end of the lumber. As a result of this weakening, normal drying conditions will create enough stress that this weakened wood will fail and that failure shows up as honeycomb at only one end of the lumber. It is common to see several honeycomb checks on one end, but only after the end coating is trimmed off. It is also common, when the bacteria is present, to find a piece of lumber that has shake (a separation parallel to the rings) as shake (or wind shake) is associated with this bacterial infection. In some species and in some pieces of lumber, we also notice a foul odor. This odor, although slight with dry wood, can return when the wood is exposed to high humidity.
Identifying the bacteria in the standing tree or in the log is difficult. Only the foul odor or the presence of shake could be used and that would not show up in every tree that is infected. In the log, shake and odor are certain indicators of bacterial problems.
Note that the odor can come back, so this wood that you have may be unsuitable for many uses. I recall one case where the dresser drawers had bacterially infected wood used for the drawer bottoms. The aroma was in the clothes. In another case, a piece of bacterially infected wood was used for a closet floor over a crawl space, so after high humidity, the closest was "odor-rific" indeed. The only cure for such a smelly problem is replacement of all of the infected wood. Be careful if you decide to use this wood.
Gene Wengert, "The Wood Doctor," has been training people in efficient use of wood for 35 years. He is extension specialist emeritus at the University of Wisconsin-Madison.
Updated: Jul 14, 2010
This article appeared in CabinetMaker+FDM, July 2010. ©Copyright 2013, All Rights Reserved.