Richard D. Bergman
Published: 2008
Total Pages: 24
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Obtaining small quantities of custom kiln-dried lumber can be an expensive process for an individual woodworker. Building and operating a small kiln capable of drying custom cuts of lumber (such as slabs, bowl blanks) gives woodworkers another option. Our approach was to build and operate a small dehumidification dry kiln. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. The first charge of mixed air-dried 4/4 hardwoods and softwoods was kiln-dried from 18.4% to 7.3% moisture content (MC) in 15 days with no casehardening. The second charge of 5/4 black cherry lumber was kiln-dried from 47.5% to 6.8% MC in 27 days with no casehardening, and the third charge of 4/4 northern red oak lumber was kiln-dried from 82.9% to 6.1% MC in 45 days and to 5.2% MC in 50 days with severe casehardening relieved by conditioning. A fourth charge of 300 bf 4/4 northern red oak, 200 bf of 4/4 shagbark hickory, and 100 bf of mixed 4/4 box elder and 4/4 black cherry was kiln-dried from 69.7% to 8.5% MC in 29 days with casehardening only in the northern red oak, and that was relieved by conditioning. We found that greater control of the dehumidifier operation earlier in the kiln schedule to maintain the safe drying rate would decrease the severity of casehardening when drying green northern red oak. New building materials, which are most of the initial cost, could be replaced by reused lumber. Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns.
