Novel polarization-type moisture meter for determining moisture content of wood above fibre saturation point

Resistance-type wood moisture meters are not reliable at moisture contents above the fibre saturation point. The aim of this study was to develop an alternative polarization-type wood moisture meter and to analyse the different calibration methods of this moisture meter in comparison with the traditional resistance-type wood moisture meter calibration method. A significant decrease (up to 3.5% of moisture content) in the tolerance interval of a single measurement was attained by introducing and integrating the original electrical wood charging number into the calibration model of the novel wood moisture meter with electric polarization effect for a high wood moisture content (MC) above 100%. The tolerance interval convergence was analysed using the traditional method of increasing the number of measurements and averaging the results and was compared to the novel method of compensating for random deviations, as used in this study. To calibrate the wood moisture meter, the wood’s electrical resistance and electrical capacitance timelines during the electrical charging cycle were registered in real time (online) with a preselected measuring speed and saved to the microcomputer memory. When the measurements were completed, the measurement data was processed by the device’s microcomputer. This novel polarization-type moisture meter allows for the moisture content of specific tree species to be predicted by selecting a suitable calibration model from a set of eight. The novel wood moisture meter can be used to monitor wood drying and to determine seasonal variations in the moisture content of growing trees.