Japanese standardized decay test methods, performance requirements and approving system are briefly described. JIS (Japanese Industrial Standard) A 9302, which is related to a testing method for evaluating effectiveness of wood preservatives when applied to pressure treatment, is fundamentally a sand-block laboratory test method. According to performance requirements in JIS A 9201, mean percentage weight of treated wood specimens should be less than 10% and 20% of that of untreated specimens against Tyromyces palustris and Coriolus versicolor respectively. JWPA (Japan Wood Preserving Association) Standard 1 covers a testing method for assessing efficacy of wood preservatives for superficial treatment. Test procedure is basically the same as JIS A 9302, although some major modifications are adopted with regard to shape and size of wood specimens, weathering cycles and the length of forced decay. Qualitative standards require that a candidate chemical should inhibit decay keeping mean percentage weight loss of treated wood specimens less than 20% of that of untreated ones in any case as prescribed in JWPA Standard 7. Results obtained by the above methods are well discussed together with other information by Japanese Examining Board of Wood Preservatives to approve a candidate chemical as a wood preservative when an application form is submitted to the board. And then the final decision will be made by JWPA [or JTCA (Japan Termite Control Association)] if the applied chemical is acceptable for approval or not.

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