Heating Frozen and Nonfrozen Veneer Logs

The available literature on log thawing and heating is reviewed, and the need for additional research is stressed. Factors inherent in the logs (diameter, green specific gravity, initial temperature, and species) are studied, as well as those inherent in the heating system (log position in vat, type of heating medium, and warm up period of the vat). Results indicate that: 1) The green specific gravity of a log is a major factor affecting the heating time. 2) The basic specific gravity alone (without information on the log moisture content) is not sufficient to predict the heating time. 3) The species in itself has little effect on heating time. 4) For a given temperature of the heating medium, water vats heat logs at about the same rate as steam vats. 5) High floating logs heat much more slowly than submerged logs, unless the air in the vat is at the same temperature as that of water, and is kept circulating. Tables of heating times for frozen logs and for nonfrozen logs are presented.

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