Indexed on: 01 Jun '70Published on: 01 Jun '70Published in: Wood Science and Technology
Measurements of the gas pressure just required to displace saturating liquids and allow a slow continuous stream of gas to pass through ponderosa pine and redwood cross sections over a broad range of thicknesses at varying distances from pith to bark, together with the surface tensions of the liquids, have been used to calculate: (1) maximum lumen radii and maximum fiber lengths from the data for the thinner specimens, and (2) maximum pit pore radii for the specimens thicker than the maximum fiber lengths. Maximum lumen radii and maximum fiber lengths both increase from pith to bark and with increasing height in the tree. Maximum effective pit pore radii increase from the pith to the sapwood transition point, then increase abruptly followed by a variable zone in the sapwood. Displacement of water or a wetting agent solution gave comparable results for never-dried wood. Drying from water and resoaking reduced the maximum effective pit pore size. Drying from a wetting agent soaked condition followed by resoaking reduced the loss in permeability but not to the degree anticipated. ponderosa pine sapwood, that had been exposed to bacterial action, showed a large increase in the maximum effective communicating opening sizes.