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Exterior weathering trials on radiata pine roofing shingles
1985 - IRG/WP 3240
A series of test roofs clad with radiata pine (Pinus radiata D. Don) shingles that had been pressure-treated with various water-borne preservative formulations were installed at a Forest Research Institute test site in Rotorua in 1977. A further series of test roofs installed in 1978 included radiata pine shingles pressure-treated with a commercial light organic solvent preservative (LOSP). Evaluation of selected radiata pine shingle test roofs in early 1984 showed that, although preservative leaching had occurred from shingles treated with an alkyl ammonium compound (AAC), a copper-chrome-arsenic (CCA) preservative, and an LOSP, the shingles appeared sound when examined microscopically. Slight lichen growth was evident on some shingles. In contrast, untreated radiata pine shingles displayed marked fungal infection, early stages of decay, and plentiful mould and lichen growth. Western red cedar (Thuja plicata D. Don) shingles, which were used as a reference point from which to judge radiata pine shingles, showed lichen and mould growth after seven years' exposure. Checking and cupping of western red cedar shingles were attributable in part to the inclusion of some flat-sawn material.
D V Plackett, C M Chittenden, A F Preston


Marine trial progress report
1980 - IRG/WP 453
In May 1977 and May 1978, tests of new chemical formulations for the protection of timber in the sea were installed in Mt. Maunganui Harbour. Investigation into new preservatives for such usage was urgently required since it had been found that there was progressive leaching of copper from copper-chrome-arsenate treated marine piles which could lead to a reduction in their service life. Hochmann (2) showed that few compounds exhibit the same toxicity to both Limnora and Teredo species. In the past it has been found that organotin compounds are among the more toxic chemicals to marine organisms. Representative chemicals of this type were therefore included in this test together with CCA retentions of 24 and 48 kg/m³ as standards from which performance of new formulations can be judged. Alternative inorganic formulations (acid copper chromate, copper silicate and ammoniacal copper arsenate) have also been included in this test. Since alkyl ammonium compounds (AAC) have been shown to exhibit some toxicity to marine borers, one of these compounds was included in the initial tests. To supplement the single formulation used in this series, copper salt-modified and alternate formulations of AACs were introduced for testing in May 1978. The treated stakes are being examined for resistance to both biological attack and leaching. In this report however, performance of the different treatments is rated by visual assessment and X-ray photographs of biological attack taken at sixmonthly intervals; chemical analyses to determine leaching rates have yet to be undertaken.
A F Preston, C M Chittenden


A selective-choice laboratory bioassay technique with Nasutitermes exitiosus (Hill) (Isoptera: Termitidae)
1983 - IRG/WP 1176
This paper presents a laboratory bioassay technique for simultaneous exposure of a variety of specimens to the same termite biomass. Details of the technique are given in a small scale selective-choice assessment with Nasutitermes exitiosus (Hill) in which timber species susceptibility is compared together with the efficacy of sub-lethal concentrations of protective compounds.
C D Howick, J W Creffield, P R Burridge