Drying of tangentially-sawn regrowth Tasmanian Eucalyptus obliqua

Abstract

The Tasmanian sawmilling industry has traditionally been heavily focused on the processing of mature eucalypt timbers. However, the available log supply has contained an increasingly high proportion of younger, smaller regrowth logs. In response to this change, the Tasmanian sawmilling industry carried out an experimental program aimed at determining a means of processing regrowth Eucalyptus obliqua into high quality sawn and dried timber similar to that available from mature logs. Initial investigations revealed that application of conventional processing techniques to the production of dried machined tangentially sawn (“backsawn”) 25 mm and 19 mm thick boards did not produce commercially viable results. Two possible techniques for reducing drying degrade were investigated: storing boards for some time prior to drying and periods of zero airflow applied intermittently during drying. Neither technique proved effective. Quartersawn timber was found to undergo less surface checking and endsplit than did backsawn. Thinner boards showed no decrease in drying degrade when compared to thicker boards.