VARIATIONS IN HOT-WATER EXTRACTIVES CONTENT AND DENSITY OF COMMERCIALWOOD VENEERS FROM BLACKBUTT (EUCALYPTUS-PILULARIS)

Extractives content and wood densities of commercial veneers of blackb utt (Eucalyptus pilularis) were determined. The extractives contents v aried from 3.3% to 14.3% on the basis of oven dry weight of unextracte d wood, whilst the wood densities varied from 727 kg/m(3) to 995 kg/m( 3) Colour analysis of these commercial veneers was carried out and the colours of the veneers were described using the CIE La*b* scale. Com pared with the data from the colour analysis, the extractives content of the commercial veneers was well correlated to redness (a) values a nd a regression equation has been obtained. Further studies using the colorimetric and the extraction methods revealed that this colorimetri c method can be an effective way to estimate the amounts of extratives on the surface of blackbutt veneers. Some of the commercial veneers h ad dark coloured areas, particularly on the loose side (the side of th e veneer containing peeler checks). This colouration was found to be d ue to deposits of ellagitannins in amounts of up to 22.9% of the dry w eight of the unextracted shavings which had apparently been carried by free water from within the veneer to the surface in the course of the veneer drying process.