IMPROVING THE QUALITY OF TIMBER FROM RED BEECH (N-FUSCA) BY INTERMITTENT DRYING

The effect of cycling the external conditions on the timber quality and drying time during seasoning has been studied for red beech (Nothofagus fusca), a difficult-to-dry New Zealand hardwood, in a laboratory batch dryer. Intermittent drying at an air temperature of 45-degrees-C and a wet-bulb depression of 10-degrees-C takes longer to yield a given moisture content than continuous drying under the same conditions, but produces timber without honeycomb or severe case-hardening as observed in continuous drying. The experiments also indicate that the timber can tolerate a higher air temperature (55-degrees-C) in intermittent drying at the same wet-bulb depression with less case-hardening and without showing honeycomb compared with continuous drying at 45-degrees-C, having a similar total drying time. intermittent drying at a a slightly higher dry-bulb temperature (60-degrees-C) and a much higher wet-bulb depression (18-degrees-C) gives a similar degree of case-hardening to that found in samples dried continuously at a dry-bulb temperature of 45-degrees-C.