There has been an increased interest in utilisation of hardwoods from eastern North America for exterior applications which require protection with preservatives such as CCA. We have examined CCA fixation at two selected temperatures of seven common North American species: red maple (Acer rubrum L.,), white birch (Betula papyrifera ), yellow poplar (Liriodendron tulipifera L.), trembling aspen (Populus tremuloides ), red oak (Quercus rubra L.), basswood (Tilia Americana ) and beech (Fagus grandifolia Ehrh.). The softwood red pine (Pinus resinosa) was included in all studies for comparison. Chromium fixation was followed by the expressate method at both ambient temperature (21°C) and at 50°C under high humidity (95%) conditions. Cr, Cu and As contents of the expressate were determined by X-ray fluorescence method and chromium (VI) was determined by diphenyl carbazide method at different times during fixation. Based on CCA fixation results it was possible to divide the examined hardwoods into a fast fixing group (beech, red oak and red maple), intermediate group (white birch and red pine) and slow fixing group (aspen, yellow poplar and basswood). Variable fixation rates for the different species are discussed in relation to different densities and different cell wall components and their contents in the different hardwoods.

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