Bacterial Oak: Drying Problems

Kiln-dried 4/4 northern red oak lumber was processed into mill work and yields were evaluated with respect to 1) normal and bacterially infected heartwood and 2) mild and accelerated kiln schedules. The presence of bacterially infected heartwood reduced yields from rough, dry lumber because of deep surface checks, honeycomb, and ring failure. Volume losses from bacterial oak lumber greatly increased with accelerated kiln-drying. Estimations were made of added production costs in the rough mill that were related to lumber volume losses from drying defects. When compared to mild-dried normal oak, added costs were higher by 23.2 percent for fast-dried bacterial oak, 6.6 percent for mild-dried bacterial oak, and 5.6 percent for fast-dried normal oak. Consequently, accelerated kiln-drying of green oak lumber is feasible for boards with normal heartwood, but not for boards with bacterial heartwood which must be dried under mild schedules. Kiln-drying of oak can be optimized by segregating bacterial oak from normal oak on the lumber green chain and drying each sort under its appropriate schedule. An accurate system for commercial presorting of bacterial oak does not exist, and the possibilities for developing one are discussed.

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