International Research Group (IRG) on Wood Protection
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ItemThe effect of copper/chrome/arsenic (CCA) treated timber on soil fungi(1981)The aim of this investigation was to study the effect of CCA treated wood on the microflora of soil with particular reference to copper tolerant soft rot fungi. The IRG collaborative field experiment was designed to monitor the performance of a range of preservative treated hardwoods with particular reference to soft rot in CCA treated timber (Dickinson 1976) and site 33 of this experiment was used in this investigation. The results clearly show that CCA impregnated timber affects the mycoflora of adjacent soil leading to increased frequency of isolation of copper tolerant fungi and particulary Phialophora spp.No significant increases in occurrence of copper tolerant fungi were noted in soil 1 cm from the wood surface indicating that the effect of treated timber is confined to a small area of soil.
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ItemThe influence of cement and calcium compounds on the performance of CCA preservatives(1983)The influence of cement and calcium compounds on the durability of untreated and CCA treated wood is considered. Calcium compounds were found to reduce the toxicity of a CCA preservative to a soft rot fungus at copper to calcium ratios of 1:1 and 1:10 using a cellulose filter paper technique. Further studies are outlined and some possible mechanisms by which cement and calcium compounds may affect the performance of CCA preservatives are discussed.
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ItemWood in concrete. Summary of discussion at IRG 14, Surfers Paradise, Australia(1984)The performance of untreated and preservative treated wood when placed in direct contact with concrete was considered in a discussion session at IRG 14. While published reports in this area are scarce, research is in progress internationally and a variety of practices are currently available to minimize any additional hazard posed by contact with concrete. This report summarizes the points raised at the IRG discussion.
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ItemEnd grain sealants for wood preservation studies(1985)The results of tests with possible end grain sealants for wood preservation studies are reported. The epoxy resins used gave satisfactory performance on wet or dry Sitka spruce and have been used with success for diffusion treatment studies.
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ItemAccelerated diffusion treatment of sawn Sitka spruce grown in the UK(1986)The treatment of 'green' sapwood and heartwood of Sitka spruce by diffusion methods was investigated. Steam/dip treatment processes gave increased solution uptakes and depths of penetration of copper in comparison with a simple dip treatment. Further investigation is required to reduce diffusion gradients with copper based formulations and to improve the penetration of 'green' heartwood of Sitka spruce by diffusion methods.
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ItemWashboard effect: A surface deformation of spruce resulting from vacuum-pressure impregnation with water-borne preservatives(1987)The washboard effect has been observed in sawn spruce after both commercial and laboratory based preservative treatments and is of increasing economic importance. The effect is defined as a specific phenomenon at the wood surface. It is distinct from internal collapse in the wood, but it may occur in association with internal collapse damage. Experimental investigations on the causes of washboarding and preliminary results indicate that a combination of several factors induce the effect. At treating pressures below about 10 bar washboarding appears to develop with post treatment drying of the wood whereas with higher pressures it will occur during the impregnation cycle. Further research has been started to develop measures to minimise the problem.
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ItemReport of the meeting of the refractory timbers sub-group, Lappeenranta, Finland on 25 May 1989(1989)The first meeting of this sub-group took place on Thursday 25 May and considered the following agenda: 1) Papers presented to the meeting "Performance of treated spruce in Canadian field test sites" by J.P.Hösli and E.E.Doyle, IRG/WP/3506 and "Performance of CCA treated spruce and pine in unsterilized soil" by A.J.Nurmi. 2) Future work areas for the sub-group 3) Membership of the sub-group 4) Circulation of information
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ItemTreatment of wood-based panel products with volatile borate(1990)The paper presents recent developments in the use of volatile borate esters for the preservative treatment of wood based board materials. Several advances on previous reports are discussed. In laboratory studies, treatment times of approximately ten minutes at 20°C on boards at equilibrium moisture content provided full penetration and retentions of 1% wt/wt boric acid. Biological tests have been conducted on a wide variety of boards treated by the vapour boron method. In all cases a retention of 0.7% wt/wt boric acid gave complete protection from decay. These results are considered with regard to parallel studies on solid wood by colleagues at the Forest Research Institute, Rotorua. The advantages of vapour boron treatment for wood based board materials are discussed.
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ItemThe effect of acid rain on CCA treated timber(1990)The effect of acid precipitation on the leaching of copper, chromium and arsenic from timber treated with different CCA preservatives was studied in the presence of three types of soil under simulated field conditions. Pine sapwood, embedded in soil, was subjected to simulated rainfall at three different levels of acidity. The CCA preservative formulations tested were:- American Wood Preservers' Association (AWPA) type B; AWPA type C; and British Standard 4072 (1974) type 1. A preliminary test of leaching with simulated rain alone (i.e. no soil) was conducted. Significant quantities of copper (40%) were lost from wood treated with all three CCAs after leaching in "rainfall" at pH 3.0 . Copper was not leached from any treated wood at pH 5.6 . Arsenic was leached in appreciable amounts (20% from wood treated with the AWPA type B formulation at both pH 3.0 and pH 5.6 and, to a lesser extent (12%), from the BS 4072 type 1 treated wood but only at pH 3.0 . Chromium was not leached from any CCA treated wood at pH 5.6, with only the possible loss of a relatively low amount (6%) occuring at pH 3.0 from wood treated with the BS 4072 type 1 CCA. In the investigation with soil, "rainfall" acidity had no significant effect on the leaching of the metals from the CCA treated wood, as detected by soil leachate analysis. This was considered to be due to the natural buffering capacity of the soils. The type of soil did have a significant effect upon the quantities of elements retained in soil and appearing in the leachate. The concentration of arsenic in leachate was greatest from sandy soil with the AWPA type B CCA treated wood, clay and peat soils retained the greatest amount of arsenic with the same formulation. The concentrations of all three elements in soil and leachate reflected the different composition of the CCA formulations.