Investigations into the photodegradation of wood using microtensile testing - Part 5: The influence of moisture on photodegradation rates

Significant increases in the rates of strength loss of thin strips were observed as a result of exposure under conditions of high humidity and water saturation. However, under some circumstances, exposure of the strips at high levels of relative humidity could result in an initial increase in tensile strength. This strength increase appeared to be associated with cellulose changes and cross-linkings. Differences in photoresistance between the different wood species, and between heartwood and sapwood, were most clearly shown under the drier exposure conditions. These differences were progressively diminished with the pronounced effect of water.