Field and greenhouse testing of window joinery of pine and spruce treated with LOSP
F G Evans, B Henningsson, E Borsholt
Norwegian window frame components of full size were double vacuum-treated with TBTN and TBTO, and connected as 'L-joints' and subsequently coated with stains. The corner sections were exposed (out of ground contact) both in field (temperated coastal climate, Taastrup, Denmark) and in a greenhouse (Uppsala, Sweden). The window frame L-joints of spruce (Picea abies Karst.) - treated and untreated showed a lower moisture content after exposure both in field and in the greenhouse than similar L-joints of pine (Pinus sylvestris L.). After 70 months' exposure the spruce had almost the same permeability level as pine heartwood and far less than the pine sapwood. Since water permeability and moisture content are regarded as decisive factors for the development of decay, spruce may therefore be considered as suitable as pine, as far as durability is concerned, when used in impregnated window joineries.