Further Studies on the Distribution of Copper in Treated Wood Using an XRF Microscope Technique

IRG/WP 11-40549

A Zahora

There are two distinct forms of copper in aqueous copper based wood preservative systems that are currently used in the United States for treatment of southern pine lumber. These are systems using either soluble copper (typically amine based) or the more recent particulate or “micronized” copper as the primary biocide. Studies reported last year showed that there were distinct differences in the gross distribution of the copper in the high density late wood and low density early wood with treatments using these two forms of copper. This study was to further investigate these two systems using an x-ray fluorescence (XRF) microscope to provide further data on the qualitative and quantitative distribution of these two forms of copper in southern pine wood and the impact of wood structure on this deposition. Commercially treated lumber treated with ACQ type D, MCQ, and MCA were selected and analyzed by XRF in cross-section in areas showing both a strong color reaction as well as an incomplete or streaky color reaction when tested with a standard spot test copper indicator. Distinctly different patterns of copper distribution were observed with the two forms of copper, with a much more uniform distribution resulting with the soluble copper system than observed with the particulate system. Both systems deposited high concentrations of copper in the resin canals and in rays, but whereas distribution tended to be very uniform across and within the early and latewood bands in the soluble system, with the particulate systems it was comparatively low in the latewood bands, high near the surface, and produced an overall streaky distribution pattern (radial orientation) throughout the treated zone. Discussion is also presented on interpretation of the XRF micrographs including how deep it is detecting copper, as well as influence of sample orientation on results.


Keywords: amine copper, micronized copper, ACQ, MCQ, MCA, copper distribution, earlywood, latewood, southern pine, XRF microscopy, x-ray florescence microscopy

Conference: 11-05-08/12 Queenstown, New Zealand


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