This part of the EN 20 series specifies a method for the determination of the protective effectiveness or the toxic values of a wood preservative against infection by Lyctus brunneus (Stephens) in wood which has been treated previously by full impregantion. This method is applicable to: - water-insoluble chemicals which are being studied as active insecticides; or - organic formulsation, as supplied or as prepared in the laboratory by dilution of concentrates. This method is applicable to water-based preservatives. NOTE – This method can be used in conjuction with ageing procedures, which do not remove the added nutrient.