Microtensile Testing of Wood – Influence of Material Properties, Exposure and Testing Conditions on Analysis of Photodegradation

This paper presents the effects of properties of tested material and exposure conditions on the final result of testing. These include density, uniformity of ring width, number of rings and latewood portions, as well as light source, presence of water and duration of exposure. Influences of these parameters in testing of several softwood species after exposure to different natural and artificial photodegradation regimes were monitored by means of changes in microtensile properties. The main findings indicate that comparisons between various species should be made taking into account average material properties, predominantly latewood portion. The fact that strength loss changes follow the same pattern during different exposure conditions indicates that there is no difference in the nature of degradation process in various weathering machines. This forms a basis for the sound comparison between the artificial and natural weathering regimes.