New Zealand grown radiata pine was treated with copper chrome arsenate preservative using Bethell process. Four different treatment schedules were tried. Keeping the duration of pressure stage constant (either 15 minutes or 45 minutes) and increasing the duration of vacuum (from 15 minutes to 30 minutes) or keeping the duration of vacuum stage constant (either 15 minutes or 30 minutes) and increasing the duration of pressure (from 15 minutes to 45 minutes) resulted in increased preservative uptake. A maximum increase in uptake (30%) was observed when the duration of vacuum stage was maintained for 15 minutes and the duration of pressure was increased from 15 minutes to 45 minutes. A maximum uptake of 558 litre per cubic meter, obtained by employing a treatment schedule of 30 minutes initial vacuum; 45 minutes pressure and 15 minutes final vacuum (30'/45'/15') was not significantly different from an uptake of 549 litre per cubic meter obtained by employing a schedule of 15'/45'/15'. Comparison of all the four schedules points to the advantage of holding a vacuum for 15 minutes and increasing the duration of pressure stage to 75 minutes to get maximum uptake and penetration of preservative.

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