Report on COST E37 Round Robin Tests: Comparison of results from laboratory and field tests

A round robin involving 15 European participants was set up in 2006. The round robin consists of both a field test according to the double layer test method and a laboratory test with two different preconditioning methods. When comparing EN 84 preconditioning (two weeks water leaching) with natural preconditioning (1 year in field, above ground) according to CEN/TS 15397, no significant difference could be noted for untreated controls, thermally modified wood or CCA impregnated wood. However, for wood treated with a metal-free organic preservative, a clear difference could be seen where much of the efficacy seen after EN 84 preconditioning is lost when natural preconditioning is used instead. In the field tests, the control pine performs similar in all fields whereas both thermally modified and preservative treated wood performs much better in the Nordic fields than in the mid- and southern European fields. The thermally modified wood performs almost as poor as the controls in the Southern European fields, whereas the organic preservative treated wood performs well in these fields. In the six mid-European fields, the organic preservative treated and thermally modified wood performs equally poor but much better than the controls. The best compliance between field performance and laboratory test results is obtained when comparing the average results from the field tests with results from EN 113 tests with Poria placenta after natural preconditioning according to CEN/TS 15397.