The relationship between pit membrane ultrastructure and chemical impregnability of wood

The woods of Alder and Eucalypt were examined by light microscopy before and after a chemical treatment by the Indurite process to increase the hardness of the wood. The pattern of wood cell impregnation for Alder differed significantly from Eucalypt in some respects. In Alder wood all cell types eg, vessels, fibres and rays, were impregnated in similar proportions. In comparison, in Eucalypt wood the impregnation material was largely confined to ray cells and the lumina of vessels; other cell types were either not impregnated or impregnated in very small numbers. Transmission electron microscopy of Alder and Eucalypt woods suggests that ultrastructural differences in the texture and porosity of pit membranes way be the main reason for the observed differences between these wood species with regard to their impregnability by the impregnation material used.