INFLUENCE OF HEAT-TREATMENT ON THE ACCURACY OF WOOD MOISTURE-CONTENT DETERMINATION BY ELECTRICAL RESISTANCE-TYPE METERS

In order to improve the accuracy of the MC determination in wood by electrical resistance-type meters the influence of heat treatment on the electrical conductivity of wood was investigated by means of fir samples (Picea abies Karst.). The samples were treated under different temperatures, exposure times and moisture content levels. The electrical resistance and the pH-values of the treated samples were compared to untreated samples. It was found that the electrical resistance of wood decreases strongly with treatment temperature and duration, while the moisture content level has a negligible effect. This could be attributed to the change of the pH-value of the samples due to the heat treatment. The results demonstrate that a calibration of the moisture meters to the individual conditions of the previous heat treatment is necessary. In other case the moisture meters calibrated to untreated samples will always indicate too high MC readings for the treated samples.