PERFORMANCE OF RESISTANCE-BASED MOISTURE METERS AS A FUNCTION OF TIMBER PRESERVATIVE TREATMENT

摘要

Three commercial resistance-based moisture meters have been used to measure the moisture content of ten classes of solid timber product specified for use in Australasia. All of the-timbers were based on Pious radiata D.Don (Radiata Pine). With the exception of a single untreated classification, the timber specimens were treated with waterborne or light organic solvent-based commercial preservatives. Moisture content data was measured and is presented as a function of relative humidity at 21 +/- 2 degrees C. Verification of timber moisture content was provided by the standard oven-dry method specified by Australian Standards/Standards New Zealand 1080.1. The results presented in this report indicate that standardisation of meter design and electrode geometry beyond that already specified within publications such as Australian Standards/Standards New Zealand 1080.1 may be required. When the individual moisture meter correction values (as supplied with each meter type) were applied to the directly measured timber resistance derived data, a l of the meters were. able to accurately determine the moisture content of untreated P. radiata to within l moisture meter units ( wt./wt.). In many instances, however, the introduction of preservative treatments significantly lowered the accuracy of the meters to a degree which was dependent on the timber preservative type and the mode of meter operation. Of particular concern was the inability of some meters to accurately determine the moisture content of typical framing timbers containing light organic solvent preservatives or certain waterborne preservatives,(equilibrated at 65 and 75 relative humidity) within at least 2 moisture meter percentage units.