Factors affecting the use of increment cores to assess fixation

Abstract

As part of an effort to ensure that treated wood products have minimal environmental and handling concerns, an American Wood Preservers Association task force is considering the development of a test to assess the degree of fixation of Waterborne wood preservatives. The proposed test involves removal and leaching of increment cores. This paper describes a laboratory study to determine how parameters such as extraction time, water volume, water temperature; depth of assay zone, and between sample variability might affect the results of such a test for chromated copper arsenate (CCA) treated wood. The results suggest that an extraction time of 4 hours would be sufficient if chromium is the element of interest. Water volume did not appear to be a concern for chromium or copper, but may be for arsenic. Leaching was affected by water temperature, suggesting that the test should incorporate temperature limitations. Depth of assay zone and location of core removal along the board did not have a great effect, especially for chromium, but this test only used cores that were fully penetrated with preservative. Because the amount of chromium leached underwent the greatest change during fixation, and because chromium leaching appears to be least affected by some of the test parameters, chromium appears to be the CCA element that is best suited for a fixation test. The low overall variability between samples indicates that this type of test could be conducted with the removal of relatively few increment cores.

Citation

Lebow, Stan T. 2001. Factors affecting the use of increment cores to assess fixation. Proceedings : Ninety-seventh Annual Meeting of the American Wood-Preservers'' Association ... Minneapolis, Minnesota, May 20-23, 2001. Granbury, Tex. : The Association, c2001: Pages 54-60