Abstract

Red pine (Pinus resinosa Ait.) sapwood samples treated with alkaline (amine) copper quaternary (ACQ) were conditioned at different temperatures and under wet or dry conditions to evaluate the stability of copper (Cu) to leaching and conversion of divalent copper (Cu-II) to monovalent copper (Cu-I). Significant Cu-II was reduced to Cu-I during post-treatment stabilization, especially at elevated temperatures (105°C and 120°C). The percent conversion to Cu-I was higher at lower retentions; in some cases, at low retentions and high fixation temperatures, all of the cupric Cu was reduced to Cu-I, raising the possibility of reduced activity of Cu as a biocide when high temperature conditions are used to fix ACQ treated wood. However, exposure of wood to a leaching procedure (rewetting, re-drying) generally resulted in a significant component of the Cu-I in wood being oxidized back to Cu-II. Steaming of weathered ACQ treated wood at 120°C also converted significant amounts of Cu-II to Cu-I.