An Inexpensive Method to Simultaneously Measure the Swelling, Shrinkage and Checking of Treated Wood

摘要

The dimensional stability of wood is easily measured, and methods have also been developed to automate the measurement of surface checking. Such measurements are usually independent whereas it would be better to simultaneously measure shrinkage/swellingand checking to better understand the relationship between surface strains and checking. In this study we describe such a measurement system. The system consists of a digital single-lens reflex camera equipped with a high-quality macro-lens. High-resolution images of transverse wood surfaces exposed to moist or dry air are captured automatically, and image analysis is used to simultaneously measure swelling/shrinkage and checking. Using this system it has been possible to quantify and compare the dimensional stability and checking of water-repellent treated pine and aspen samples with those of matched, untreated, controls. Surface checking developed solely during drying in both treated and untreated pine samples, however with less severity in water-repellent treated samples. The water repellent was able to restrict dimensional changes of aspen samples. We conclude that the system we have developed shows promise for screening water-repellent treatments for wood, and also obtaining a better understanding of the relationship between surface strains and checking of treated wood.