Shrinkage recent wood

A similar sorption isotherm has been published for 2500-year-old waterlogged alder 21). EMC values were consistently about twice as great as comparable values for recent wood over the entire hygroscopic range. Additional data collected in Table III include EMC values at or near 100% relative humidity for fir, alder, and a series of oak finds. In many cases the residual density values are greater than 100%, probably because of enhanced shrinkage affecting the determination of air-dry density rather than a com-... 

Shrinkage or swelling data for the three principal directions of buried wood, as well as comparative values for recent wood, have been collected in Table IV. Recent wood values were taken from the publications cited, and no attempt was made to provide recent wood values when not provided... 

Table IV. Shrinkage or Swelling of Buried and Recent Wood...

Table IV shows that the old wood, with the exception of two Scots pine finds, always shrinks more than recent wood. Age alone does not emerge as a sole factor by which increases in shrinkage can be estimated. Increases...

Figure 2 is a plot for volumetric shrinkage of waterlogged oak (i). It shows that at the same maximum moisture content level (indicating equal values of conventional density and thus no mass loss), the waterlogged wood nevertheless would have more than twice the shrinkage of recent wood. Although there may have been no net mass loss, some wood substance could... 

Figure 3, Longitudinal shrinkage ratio of old and recent wood as a function of residual density, from the data of Table IV.

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