When attempting to enforce standards of penetration and retention set for treated timber, the regulating authority must establish a sampling or inspection scheme which will prevent large quantities of substandard product entering the market. On the other hand, the scheme should not penalise treaters for the small quantities of such material which are inevitably produced by any industrial process. Thirteen alternative sampling schemes which could be used to periodically sample individual treatment plant production are compared. The risk of allowing continued production of excessive unacceptable material is compared with the risk of unfairly penalising the treater for producing only small amounts. Schemes are evaluated in terms of the effect of sample size, number of permissible failures at each sampling, and number of warnings issued before taking action. Schemes which present the best balance between opposing risks are identified.

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