Comparison of four methods for drying bacterially infected and normal thick red oak

There is a need to optimize the drying of thick oak lumber containing bacterially infected heartwood. Even with slow drying, excessive losses from checks, honeycomb, and ring failure often occur. To provide a basis for solving this problem, mixed kiln loads of bacterially infected and normal 9/4-inch-thick northern red oak lumber (Quercus rubra L.) were dried from green to 6 percent moisture content (MC) by four different processes: conventional kiln-drying from green; dehumidifier kiln-drying to approximately 20 percent MC followed by kiln-drying to 6 percent MC; predrying in a commercial predryer to approximately 20 percent MC followed by kiln-drying to 6 percent; and vacuum drying. Volume losses in the bacterially infected lumber were 20.4, 17.1, 7.0, and 16.5 percent, respectively, for these four processes and 0.5, 1.6, 0.3, and 2.5 percent, respectively, for the normal lumber. Vacuum drying was the fastest, requiring only 29 days; dehumidifier/conventional kiln-drying, took 131 days; conventional kiln-drying from green required 135 days; and predrying/conventional kiln-drying took 165 days. These results indicate thick normal oak can be quickly dried from green to 6 percent MC with the vacuum method, and optimal drying of thick bacterial oak would probably require a combination of low-temperature predrying followed by vacuum drying.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member