Effect of brief presteaming on shrinkage,collapse and other wood-water relationships in Eucalyptus regnans F. Muell

Summary Brief presteaming of green, increment-core segments of mountain ash (E. regnans F. Muell) produced small but significant changes in a number of moisture-shrinkage parameters. Both total volumetric shrinkage and recoverable collapse were significantly greater in presteamed samples, the increase in collapse being largely attributable to an increase in moisture content after reconditioning (M_r). The change in shrinkage after reconditioning also was significantly related to changes in M_r. The change in M_r was interpreted as reflecting altered permeability in presteamed material and was shown to be negatively related to estimated residual collapse. Initial moisture content and per cent saturation showed a highly significant decrease after presteaming, while green volume showed a small but significant increase. Neither the estimated intersection point, unit shrinkage nor the R-ratio were significantly different after presteaming. However, the unit shrinkage-specific gravity relationship was changed by presteaming such that it more closely complied with Stamm's approximation.The author expresses his appreciation to Dr. Alan Miller for assistance with statistical analysis and to Mr. Chris McEvoy for technical assistance