Observed relationships between wood density and solution uptake during pressure treatment

Abstract

A better understanding of the relationship between wood properties and solution uptake during pressure treatment could lead to improvements in treatment quality and more efficient use of preservatives. In this study several years of treatment data representing a range of wood species, charge conditions and preservative formulations were analyzed to evaluate the relationship between wood density and solution uptake. Density and solution uptake (weight gain per unit volume) were determined for individual specimens in each charge. The analysis revealed that in many cases there was little or no relationship between wood density and solution uptake. When a relationship was present it was negative (more dense specimens tended to have lower uptakes). The strongest relationship between wood density and solution uptake was generally found with southern pine, and the weakest relationship with the less easily treated softwood species. Smaller specimens exhibited a stronger relationship between uptake and density than larger specimens cut from dimension lumber. The relationship between wood density and solution uptake appeared to be slightly stronger for oil-type preservatives than water-based preservatives, but this effect was not as apparent as those of wood species and specimen dimensions. In general, the results of this analysis indicate that a consistent relationship between wood density and solution uptake should not be expected for lumber and timbers treated with current commercial schedules.

Citation

Halverson, Steve; Lebow, Stan. 2011. Observed relationships between wood density and solution uptake during pressure treatment. In: Proceedings, one hundred seventh annual meeting of the American Wood Protection Association. Fort Lauderdale, FL, 2011 May 15-17. Volume 107. Birmingham, AL: American Wood Protection Association, c2011: p. 93-98.