Evaluation of Moisture Content Changes in Taiwan Red Cypress During Drying Using Ultrasonic and Tap-Tone Testing

Moisture content affects most of the important properties of wood, therefore it is important to control during drying and in use. The purpose of this study was to investigate moisture content changes in Taiwan red cypress during drying. Two types of nondestructive testing were used, ultrasonic and tap-tone. The results showed that ultrasonic and tap-tone velocities increased with decreasing moisture content with the major effect below the FSP. A second-order regression relationship was found between ultrasonic and tap-tone velocities with moisture content desorption during drying with a coefficient of determination of 0.77 and 0.88, respectively. Moreover, the effects of moisture content desorption on dynamic moduli, calculated from ultrasonic and tap-tone methods, were demonstrated. Finally, a new parameter (Vi/Vx), the ratio of initial velocity (before drying) to the velocity at any moisture content, was effectively applied to evaluate moisture content changes in wood during drying. The tap-tone method was found to be a reliable tool to measure moisture content changes during the drying of wood