The background to current commercial CCA treatment schedules used in New Zealand and fixation processing is reviewed. The limitations of these conventional practices with respect to treated product quality and CCA solution handling issues are defined. A novel, patented treatment schedule has been developed using a combination of hydraulic and pneumatic pressure phases and hot (~ 75°C) CCA solutions. The hydraulic phase effects preservative impregnation into the wood while CCA fixation occurs during the pneumatic phase. A final vacuum is drawn at the end of the pneumatic phase. Kickback solutions collected at the end of pneumatic and final vacuum stages are kept separate from the working solution for processing to remove organic carbon before return to the store tank.

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