Indirect Measurement of Pore Size and Permeability in Scots Pine and Norway Spruce

Abstract

Five experiments to investigate the water relationships of Scots pine and Norway spruce sapwood are described. Field exposure of stakes, and their moisture characteristic relating wood moisture content to the water potential of the surroundings showed that spruce had a lower moisture content than pine under the same conditions. A pore size distribution derived from the characteristics showed more large pores in spruce than in pine, but in spruce there were also more small pores. The inference was that the large pores of spruce were readily accessible to water, allowing a fast rate of water uptake, as found in the wick action and swelling investigations, while the small pores were not accessible, resulting in a low rate of water uptake and a low rate of swelling. The possibility is briefly discussed that it is the pore size distribution of the two woods which determines their water relationships, and the difference in pore size which determines their treatability.