Low-Frequency Measurement of Moistened Wood-Based Materials

Abstract

This article examines how water content is a crucial parameter for the preservation of wooden artworks and buildings, focusing on non-invasive ways of measuring water content through capacitive methods. A personalized, low-cost probe to measure the dielectric properties of oak and poplar wood at various water content levels and frequencies is described. The accuracy of the probe is confirmed by testing it with reference materials like air, PTFE, PLA, glass and Bakelite, demonstrating an accuracy error below 2%. Next, the probe is used to evaluate the relationship between water content and permittivity, indicating possible uses in conservation projects. Measurements were conducted on two types of wood, poplar and oak, at five varying levels of water content. The dielectric permittivity between 10 and 100 kHz was assessed. Using the vertical shift from the single interpolant of the dataset, a graduation curve was estimated. Finally, an R2 = 0.98 value demonstrates that a sigmoidal function reflects the relationship between the percentage water content and the permittivity of materials