Method for interconverting drying and heating timers between round and square cross sections of ponderosa pine

To use small-diameter trees effectively as square timbers, we need to be able to estimate the amount of time it takes for these timbers to air-dry. Since experimental data on estimating air-drying time for small-diameter logs have been developed, this study looked at away to relate that method to square timbers. Drying times were determined for a group of round cross-section ponderosa pine logs and a group of square timbers. With regression analysis used to relate the two groups, it was shown that there is a square cross section of dimension S that results in the same drying time as a round cross section of diameter D, and the relationship between the two dimensions is S = 0.900D. This relationship allows the conversion of previously published estimates of air-drying times for ponderosa pine logs to air-drying times of square timbers. The conversion is only valid if the sapwood/heartwood ratio is not altered by the round to square conversion. An analysis of analytically calculated heating times for heat sterilization of round and square cross sections further verified the relationship, as well as showing it also is applicable to interconverting heating times between round and square cross sections when one is known but the other is not.

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