A shower test protocol for measuring antisapstain wash-off from small individual log billets
A J Pendlebury, H Pearson
According to New Zealand Timber Industry Federation statistics New Zealand exported 4,835,000 m³ of logs in 1994 and it is estimated that c. 20% were anti-sapstain treated. Loss of preservative from logs as a result of rain impact after application is of considerable concern both with respect to potential loss of efficacy and environmental contamination. Whilst Environment Canada have a proposed standard for assessing run off from anti-sapstain treated sawn lumber, the method does not readily allow for the evaluation of anti-sapstain treated logs under relevant time frames, or conditions, for the New Zealand situation. In addition, most of the other available and commercially relevant leaching, or shower tests, were designed to evaluate leaching from vacuum-pressure treated square sawn lumber, or round posts. A test method, loosely based on established methods and developed with the support of industry, is described which quantifies the leaching, or surface run-off of preservatives (ie. anti-sapstain products) from small (£ 45 cm diameter) treated log billets under real time, or accelerated conditions. The method also allows for the influence of several key variables on leaching / surface run-off from anti-sapstain logs to be quantified through manipulation of shower test rig parameters such as: water droplet size & flow rate; log coverage; spray jet shape or angles and shower period (intermittent or single dose).
Keywords: ANTI-SAPSTAIN CHEMICALS; LEACHING; LOGS; TEST METHODOLOGY; SHOWER TEST