No international standard method for testing anti-stain chemicals for protecting fresh sawn timber exists. The methods used can be divided into three types: a) Rapid screening tests for finding chemicals effective against blue-stain and mould fungi. The chemicals are tested in agar medium, in pieces of filter paper or on small pieces of wood using pure cultures. b) Laboratory tests for evaluating the effectiveness of a preservative and estimating the minimum concentration for the treating solution. Wooden test pieces of different size and artificial infection are used. c) Field tests for evaluating the effectiveness and performance of a preservative under practical conditions. The fungal infection is mostly natural. There is a need for standardisation of the method especially for the tests of type b, to be able to repeat the tests and have comparable results. The results from field tests are always dependant upon the natural conditions that vary between places and even in the same place. Besides, a field test often tries to simulate the local service conditions. However, standardisation of the techniques and of the principle of evaluation might faoilitate the conduction of tests, and the comparison of the results. In this paper, a short summary is made on the variables in the present tests, that should be subject to unification. The summary is based on literature, that is not complete. The differences in the present methods are so numerous that they cannot be discussed here in detail.

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