The development of blue stain in service in sapwood of European softwood species
IRG/WP 97-10236
J Van Acker, R Klaassen, H Militz, M Stevens
The utilisation of softwood species for window joinery applications is gaining importance in countries frequently using tropical hardwood species up to now. Since wood preservation is not always part of the total concept of window frames manufactured from sapwood containing wood elements it is essential to know the impact of durability on the performance. Moisture content control is a major tool in achieving an acceptable service-life regarding wood rot. The development of blue stain can be prevented in a similar way but other parameters than natural durability are to be considered, too. This study evaluated the development of blue stain in service in sapwood of four European softwood species: scots pine, spruce, douglas fir and larch. The results were compared with data on porosity of the same samples. As a conclusion it can be stated that not only the physical protection from water penetration is important but that the wood water relationship of a softwood species plays a major role in the development of blue stain in service, as well.