Shower test methods were developed a number of years ago to address rising concerns with the potential loss of wood preservatives into the environment from exposed treated wood products in service. The Netherlands was instrumental in pursuing such methods although a variety of such concepts are now used in various countries.
In concept, simulated rainfall is allowed to fall on treated wood and the runoff water is collected and analyzed for preservative content. The methodology was originally used to develop data on relative losses of preservative treated wood into the environment, although correlation between this "laboratory" procedure and actual losses in service situations is difficult because of use configurations, as well as climatic differences in service.
One important area where the methodology has been adapted to is in measuring the relative movement of surface applied stain and mold treatments from logs held in storage piles prior to use or shipment. This will continue to be an area of interest as global trade and movement of logs from areas of sustainably grown forests to regions of high efficiency processing continues to increase within the modern world economy.