Measuring Retention of Chromated Copper Arsenate in Conifer Sapwood by Direct-Scan X-Ray Techniques

Abstract This study was designed to indicate how well direct-scan X-raying predicts preservative retention and distribution of chromated copper arsenate (CCA) in wafers of conifer sapwood. The intensity of X-rays passed through western hemlock wafers treated with varying concentrations of CCA solutions was inversely proportional to preservative concentration. X-ray intensities predicted 98% of the variation in preservative retention among the wafers. Intensity of direct-scan X-rays passed through selected test materials was consistent over a 9-month span. X-ray intensity over 1000 readings at a single scan point had a coefficient of variation of 0.1%. The strong relationship between direct-scan X-ray intensity and preservative retention, as well as the repeatability of intensity readings over time and the small variation in intensity readings at each data point, indicate that direct-scan X-ray techniques can be used to assess preservative retention and distribution in wood treated with inorganic arsenical...