Time of Wetness (ToW) simulation based on testing moisture dynamics of wood

Within the framework of CEN/TC 38 (European Committee for Standardization / Durability of wood and wood-based products) the WG 28 (Working Group Performance classification) have been established to harmonize, especially for use class 3 applications, views on durability aspects of wood species, preservative treated and modified wood. The related EU project PerformWood established the concept that natural durability and/or enhanced durability is not solely based on the presence of active ingredients having an impact on both fungi and insects. The material resistance complementary to this is also based on the time of wetness factor. Based on earlier results for plywood experiments were set up for solid wood. For plywood a simulation of time of wetness measured by continuous moisture measurements (CMM – Figure 1) (Van den Bulcke et al. 2009, 2011) was possible by using a floating test including wetting and drying components. For solid wood a soaking/submersion test procedure was added as a second test to distinguish between optimal design of a commodity and design including water trap. These methods have been used in a round robin and results were presented earlier by Brischke et al. (2014).