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In-ground performance of two formulations of chlorothalonil after five years of exposure at three test sites in Australia
1996 - IRG/WP 96-30101
Sapwood specimens of Pinus radiata D. Don and Eucalyptus regnans F. Muell. were each treated to three retentions of each of two preservative formulations (chlorothalonil in oil; chlorothalonil plus chlorpyrifos in oil) and installed in-ground at three field test sites in Australia. Specimens were treated with each formulation to achieve 3.2, 6.4 and 12.8 kg/m³ of chlorothalonil a.i. and 3.2 + 0.2, 6.4 + 0.4 and 12.8 + 0.8 kg/m³ of chlorothalonil plus chlorpyrifos a.i. For comparison, specimens of each timber species, treated to a commercial in-ground retention of a copper-chromium-arsenic (CCA) formulation, were also installed. Treated specimens (including controls) have been rated for their condition annually for attack by subterranean termites and fungal decay using a scale ranging from 4 (sound) down to 0 (failed). After five years of exposure, mean termite and decay scores for replicate test specimens at each site reveal that the performance of all three retentions of each formulation, particularly the two highest retentions, is comparable to CCA.
J W Creffield, T L Woods, N Chew


An in-ground natural durability field test of Australian timbers and exotic reference species. Part 2: Progress report after approximately 13 years' exposure
1983 - IRG/WP 1189
The condition of heartwood specimens of Australian and exotic timber species after approximately 13 years' in-ground exposure is given. Four of the 5 test sites have a termite hazard in addition to the hazard from a range of decay fungi. Values for specimen life are given only where all replicates of a timber species have become unserviceable. Results give evidence leading to doubt about the accuracy of the tentative durability ratings previously ascribed to at least some of the species under test.
J D Thornton, G C Johnson, I W Saunders


Biological effectiveness of ground-contact wood preservatives as determined by field exposure stake tests
1984 - IRG/WP 3297
Field exposure tests conducted on stakes treated with different creosotes, mixtures of creosote and waxy oil as well as different CCA wood preservatives over a period of 25 years, gave the following results: The CCA preservatives provided excellent biological protection to treated stakes, especially against fungal attack. The CCA Type I, currently approved for use under South African conditions is not inferior to the CCA Type II during long-term ground-contact exposure if the active elemental contents and effective retentions are taken into consideration. The creosotes provided good protection against termite attack but showed fairly poor fungal resistance during long-term ground-contact exposure under wet conditions. The addition of waxy oil greatly improved the effectiveness of creosotes against fungal attack. The CCA preservatives proved to be a better overall ground-contact preservative compared with the creosotes.
W E Conradie, A Pizzi


Effect of felling time related to lunar calendar on the durability of wood and bamboo -Fungal degradation during above ground exposure test for 2 years- (Preliminary report)
2005 - IRG/WP 05-20311
Current study was carried out to know whether the felling time of trees and bamboos based on lunar calendar affects natural durability of felled wood-bamboo or not. Each of one sugi (Cryptomeria japonica) tree of 28 years old and one Moso bamboo (Phyllostachys heterocycla) of around 3 years old was cut 12 times between February and December in 2003. Six sets of sugi tree and bamboo were felled in a day during “Hassen” period and the other 6 sets of them were also felled in a nearby non-“Hassen” day. There is a belief that “Hassen” should be avoided to perform destructive works such as cutting trees. “Hassen” lasting 12 days based on lunar calendar appears 6 times every year. After felling sample trees and bamboos, these specimens were subject to outdoor exposure at above ground level for 2 years. Properties of specimens such as moisture contents, mould and fungal resistance were examined periodically for 2 years. There was no clear difference in the degree of mould growth on the surface between specimens felled in a “Hassen” day and those felled in a non-“Hassen” day in the same month. The felling seasons, however, influenced the growth of mould on the surface of wood and bamboo clearly, which has been traditionally known in many cases. Fungal degradation evaluated by visual observation and the depth of pin penetration using Pilodyn during 2 years exposure was not affected by not only “Hassen” or non-“Hassen” also seasons when tree and bamboo felled.
K Yamamoto, S Uesugi, K Kawakami


Effect of permeability and extractives on the decay rate of southern pine sapwood in above grund exposure
2005 - IRG/WP 05-20310
The effects of wood permeability and hydrophilic and hydrophobic extractives on the decay rate of southern pine sapwood in above ground exposure were investigated. Permeability was determined by water sorption measurements, and the effect of extractives was studied by pre-extracting the test samples prior to outdoor exposure using water to extract hydrophilic extractives or sequential methanol/cyclohexane extractions to remove hydrophobic extractives. Initial water permeability of the wood prior to outdoor exposure was highly correlated to decay rate, with the more permeable samples decaying more rapidly. Removal of the hydrophilic extractives prior to exposure decreased the decay rate, but the effect was not statistically significant at the 0.05 level. Conversely, removal of the hydrophobic extractives significantly increased the rate of decay, even though it had no effect on the initial water permeability.
D D Nicholas, T Schultz, L Sites, D Buckner


Moisture condition in treated wood exposed outdoors. A progress report after 5 years
1992 - IRG/WP 92-3720
Wood treated with water-borne preservatives, mainly CCA (copper, chromium and arsenic) and CCB (copper, chromium and boron) is often said to absorb more water than untreated wood. In laboratory tests this statement has not been confirmed (Johansson 1977). In 1986 a project was started to compare water absorption during outdoor exposure between wood stakes of pine, Pinus sylvestris L, and spruce, Picea abies, both untreated and treated with different preservatives. For comparison untreated stakes of different species were included as well as painted pine stakes. Results after 28 months' exposure were reported in IRG/WP/3533, 1989. In this document results after five years are reported.
M-L Edlund


Ammoniacal wood preservative for use in non-pressure treatment of spruce and aspen poplar. Part 1
1984 - IRG/WP 3273
End-matched lumber of Picea glauca (Moench)Voss (white spruce) and Populus tremuloides Michx. (aspen poplar) timbers was treated by a thermal diffusion process in open tank treating vessels using an ammoniacal copper-arsenate wood preservative. The process proved technically feasible with respect to controlling the vapourization of ammonia from open tanks during treatment at high temperatures. Treatments of 48 hours or more on unseasoned and partially dried lumber produced net oxide retentions above that required by the Canadian Standard Association CSA-080 wood preservation standard for timber in above ground contact situations. Although preservative penetrations did not meet the penetration requirements (10 mm), of the CSA 080.2 standard for ground contact, five of the seven non-pressure charges on spruce lumber had heartwood penetrations greater than 7 mm in depth. A 24-hour treatment on air-dried spruce had penetrations equivalent to a five-hour vacuum-pressure treatment. Retention was adequate for above-ground exposure
C D Ralph, J K Shields


An in-ground natural durability field test of Australian timbers and exotic reference species. Part 5: Extensive data from a site where both decay and termites are active. Results from a full-replicated set of heartwood specimens from each of ten myrtaceous hardwoods after 18, 19 and 20 years' exposure - A discussion paper
1988 - IRG/WP 2324
Extensive data are presented on the decay situation, the termite situation and the decay-termite associations; all gathered from a fully-replicated set of heartwood specimens of 10 hardwood timbers after 18, 19 and 20 years' exposure in the ground at a single test site, i.e. a semi-arid steppe site. Sixteen tables are presented in addition to the one table providing the rating data; the latter representation of specimen condition being essentially all the data normally being recorded from field tests, whether these be of natural durability or preservative treated specimens. The authors give this "extra" data to show the type of information obtainable as a result of applying both mycological and entomological expertise to field assessments. Instead of discussing these results. the authors wish to generate some discussion by asking questions such as - is some of all of this information of value? - What additional/alternative information would interested scientists wish to see with respect to the most durable timbers in a test such as that examined in this report?
J D Thornton, G C Johnson, J W Creffield


International comparison of three field methods for assessing the in-ground termite resistance of materials - highlights after two years
1999 - IRG/WP 99-20157
First-year results of a comparative study, evaluating the in-ground termite resistance of a range of materials, including CCA and ACQ-treated timbers, using the below-ground exposure, ground contact and graveyard methods against diverse termite faunas were provided in IRG/WP/98-20132. Further annual inspections have confirmed early trends and identified notable differences between sites and methods. Termites have contacted specimens more frequently at tropical sites, irrespective of the method, and in below-ground exposure trials, irrespective of site. Overall, levels of fungal decay have been low. Fungal decay was more prevalent in specimens using the ground-contact and graveyard methods. Notable levels of termite attack have been recorded for some CCA- and ACQ-treated Pinus radiata specimens at the retention of 2kg/m3, after two years or only one year (Phuket, Thailand). Some specimens of the durable timber bald cypress (Taxodium distichum) have sustained significant levels of termite attack and fungal decay.
M Lenz, J W Creffield, A F Preston, B M Kard, C Vongkaluang, Y Sornnuwat


BRE Experience in monitoring decay in out-of-ground exposure trials
1995 - IRG/WP 95-20077
The outdoor field trial has always been regarded as the ultimate test of performance for assessing the effectiveness of a wood preservative. For this reason, the Building Research Establishment (BRE) has invested much effort in such trials over many years. Emphasis in early trials was on ground contact tests which were the basis both for assessing the likely performance of a preservative in protecting posts and poles, and for classifying a timber's natural resistance to fungal decay. When preservation of timber in the building and construction industry assumed greater importance, the emphasis was placed on the development of out-of-ground field trials to provide data on the likely performance of exterior joinery work in buildings. For these tests, the exposure conditions provided a less severe hazard for out-of-ground timber than for wood permanently in contact with the ground. Out-of-ground trials have been running at BRE since 1967 (Orsler and Smith, 1993) initially using T-joints and L-joints and later the window joinery test rig was established to provide conditions close to those in buildings (Purslow, 1975). All the early trials were assessed only by visual assessment for decay. Later still, small L-joints with a coating (the methodology which was used as the basis for EN 330) were used for a comprehensive study to establish the pattern of colonisation by microorganisms and associated changes to the wood. It was established that the basidiomycete fungi ultimately responsible for the decay are the climax of a colonisation sequence of a range of types of fungi plus bacteria (Carey, 1980). In an attempt to give early indications of long term performance, colonisation by basidiomycetes and changes in the porosity of the wood during exposure have been used as the basis for assessing performance relative to that of a reference preservative (1.0% tri n-butyltin oxide). Hyphen joints were introduced (Orsler and Holland, 1993) for studies of preservative distribution.
J K Carey, R J Orsler


A below-ground exposure method for determining the resistance of woody and non-woody materials to attack by subterranean termites
1993 - IRG/WP 93-10012
With existing field test procedures, in which specimens are installed vertically to some of their length into the ground and spaced out from each other ("grave-yard" tests), variations in the rate of contact by termites between replicates can be common. Mechanical damage to specimens during inspection and re-installation may also be difficult to avoid. A new field test method, evaluated in Australia, is described. Close to nests of or within the most active foraging sites of target species of termite, test specimens are exposed horizontally below the grownd in trenches (300 mm deep). The base of the trench is lined with strips of termite-susceptible timber. On top of the strips, specimens of susceptible timber and test specimens are layed adjacent to each other in alternating sequence. These are covered with additional strips of timber. Finally the test trench is backfilled with soil. Offering specimens together with a concentrated supply of susceptible timber below the soil surface provides an attractive food source and an environment that is conducive to sustained foraging by termites. Under Australian conditions brown, white and soft rots were present in timber specimens buried horizontally in the soil at a depth of 300 mm. The below-ground exposure method is very versatile and can be used for assessing the resistance of a wide range of materials of any shape. Inspections and re-installations of tests can be performed with ease and without causing damage to test specimens.
M Lenz, J W Creffield


Comparison of three methods for assessing the in-ground termite resistance of treated timber, durable timber and plastics at sites in Australia, USA and Thailand - First results
1998 - IRG/WP 98-20132
The in-ground resistance of materials to attack by subterranean termites is most commonly assessed with one form or another of the conventional graveyard method, despite the significant shortcomings of this method. In Australia, an alternative method, in which all samples of test materials are placed below-ground, has been in use for more than 10 years. The method provides reliable exposure of samples to prolonged contact by termites and offers a number of other advantages, notably ease of removal and re-installation of specimens, and protection from fires or damage caused by animals and vandalism. We describe a study in which assessments of materials with the below-ground exposure method were compared with the graveyard procedure and a modification of the South African ground contact method. Sites encompassed a range of climatic conditions and termite faunas, subtropics with species of Reticulitermes in Mississippi, USA; humid tropics with a diverse termite fauna dominated by Macrotermitinae (fungus-culturing termites) in SW Thailand; wet and dry tropics with separate trials for the two economically important species, Mastotermes darwiniensis and the mound-building form of Coptotermes acinaciformis, in Northern Australia; and at a semi-arid inland site with a temperate climate in Eastern Australia where the tree-nesting form of Coptotermes acinaciformis is the dominant species. Materials included in the investigation were: CCA- and ACQ-treated Pinus radiata (each at two retentions), a durable timber (bald cypress, Taxodium distichum) and two plastic cable sheathings (nylon and low density polyethylene). This paper provides details of the trial and gives first observations from inspections at three sites after one year of exposure of the materials to termites.
M Lenz, A F Preston, J W Creffield, K J Archer, B M Kard, C Vongkaluang, Y Sornnuwat


A laboratory technique to measure the performance of preservative treated hardwoods in ground contact
1982 - IRG/WP 2172
A laboratory technique to measure the performance of preservative treated timber in ground contact is described. It uses partially sealed blocks of timber which are treated, leached and sawn into small stakelets for soil exposure in a fungal cellar. Performance is monitored by the loss of static bending strength with time, and a simple apparatus for measuring the deflection of a stakelet under a load is described. Birch, Scots pine, and four Eucalyptus species were tested untreated and treated with a CCA preservative. Results show that the wood was attacked by soft rot, that attack could be detected rapidly and accurately using the loss of static bending strength, and that results confirmed field trial and service data. The technique is rapid, simple, accurate and realistic.
E F Baines


Above-Ground Durability Estimation in Australia. Results after 16 years exposure
2005 - IRG/WP 05-20314
A program of research was established in 1987 to examine the above-ground durability of a selection of timbers that are commercially significant in Australia. Test samples were assembled in an L-Joint design and placed on exposure racks in a format to replicate joinery that is exposed to the weather above ground. Both painted and unpainted material has been exposed. Test samples have been evaluated regularly over the sixteen-year exposure period, and although the trial is not yet complete, the research has highlighted and provided data on the effect of painting, the source of timber and the influence of location. Biodeterioration models are now being developed and as the exposure approaches completion, the models will be further refined using results that emerge for the more durable softwoods and hardwoods that are incorporated into the project. As data is finalised for a particular species, it is to be submitted to the national standard for timber durability as well as design for durability programs currently underway in Australia.
L P Francis, J Norton


The performance of metal-chromium-arsenic formulations after 32 to 38 years' in-ground exposure in Australia
2000 - IRG/WP 00-30240
Two trials of metal-chromium-arsenic preservatives were exposed in-ground in Australia. In Trial 1, Pinus radiata stakes treated with Boliden K.33, Boliden S.25, Celcure A, Tanalith C and Tanalith CA were installed at Sydney and Narrandera in 1961/1962. In Trial 2, P. radiata and Eucalyptus regnans sapwood were treated with Celcure A, Celcure A21-N, Celcure A 21-O and Tanalith CA (new) and installed at Sydney and Innisfail in 1966/1967. In Trial 1, all metal-chromium-arsenic preservatives at 8 and 12 kg m-3 gave median specimen lives in excess of 35 years. As none of the stakes treated to 12 kg m-3 with Boliden K.33, Celcure A, Tanalith C or Tanalith CA had become unserviceable, the minimum guarantee period for these preservatives is greater than the present exposure periods. In Trial 2, the four CCA preservatives when impregnated into P. radiata sapwood at 12 kg m-3 gave median specimen lives at Sydney of greater than 32.5 years. With E. regnans sapwood treated to 12 kg m-3, only Celcure A 21-0 gave a median specimen life at Sydney of greater than 32.5 years. At the high decay and termite hazard site of Innisfail, Celcure A 21-0 protected the eucalypt better than any of the other CCA formulations.
G C Johnson, J D Thornton, J Beesley


Effect of climate, species, preservative concentration and water repellent on leaching from CCA-treated lumber exposed above ground
2001 - IRG/WP 01-50178
Few studies have examined leaching of chromated copper arsenate (CCA) from treated wood in above ground exposures due to the assumption that leaching is less severe compared to wood in continuous contact with soil or water. However, a significant portion of CCA treated wood is used for above ground applications, exposing considerable volumes of the preservative to precipitation and potential leaching. This paper presents preliminary results of a one-year study that continuously monitors CCA leaching from above ground, naturally exposed 5.08 cm x 15.24 cm (2 x 6 inch) dimensional lumber. Three wood species, southern yellow pine (Pinus spp.), jack pine (Pinus banksiana Lamb.), and black spruce (Picea mariana (Mill.) B.S.P.), along with two preservative concentrations and one commercial water-repellent are evaluated for their effect on leaching rates. Preliminary leaching results indicate significant differences between wood species, treating solution concentrations, and the use of water repellent. In addition it appears that climatic variables affect elemental leaching of copper, chromium and arsenic differently. However, the exact effects of climatic variables are inconclusive at this time. Upon completion, this study will offer a substantial amount of leaching data to validate the findings of previous leaching tests, and provide insight into the leaching mechanism of CCA-treated lumber in above ground exposures.
J L Taylor, P A Cooper


Pentachlorophenol and tributyltin oxide - the performance of treated Pinus radiata after 12 years' exposure
1986 - IRG/WP 3361
Pinus radiata samples were impregnated with a range of light organic solvent preservatives and copper/chrome/arsenic salt and exposed with no surface coating both in and above ground for 12 years. Inspection of the test samples revealed that some formulations of light organic solvent preservatives will give good fungal protection and reduce splitting in Pinus radiata exposed externally without a supplementary surface coating. Tributyltin oxide performed poorly in the test compared to pentachlorophenol which gave relatively good protection under both hazard conditions. Copper/chrome/arsenic salt was clearly the most effective.
R S Johnstone


Efficacy of copper:propiconazole and copper:citrate systems in ground contact exposure at a site with copper tolerant fungi
2003 - IRG/WP 03-30305
Southern yellow pine (SYP) sapwood field stakes were treated with copper alone (ammoniacal copper carbonate, ACC) at four levels, or three levels of copper (1.6, 3.2, or 6.4 kgm-3, as CuO), air-dried, then re-treated with propiconazole in a light organic solvent at 0.07, 0.3, or 0.7 kgm-3 retentions. In a separate study, SYP field stakes were treated with three levels of ACC to give 6.7, 13.4 or 29 kgm-3 retentions, or the same ACC levels plus citric acid at 38% of the CuO level. These ground-contact stakes were installed at a test plot which has copper tolerant fungi, and inspected regularly for fungal and termite degradation. At the most recent inspection, the copper azole stakes had been exposed for 118 months and the copper citrate stakes for 100 months. For the copper azole stakes, copper alone was only effective at the highest copper retention (10 kgm-3, CuO basis). In contrast, the copper azole-treated stakes were adequately protected with 1.6 kgm-3 CuO and the highest (0.7 kgm-3) level of propiconazole, or 3.2 kgm-3 CuO and 0.3 or 0.7 kgm-3 propiconazole, or 6.4 kgm-3 CuO and 0.07 kgm-3 (or greater) propiconazole. For the copper citrate stakes, stakes treated with copper alone performed slightly better at all three retentions than the copper:citrate-treated stakes. We conclude that the co-addition of propiconazole provides increased protection against copper tolerant fungi and other wood-destroying organisms, with increased azole levels necessary as the copper retention is lowered. In contrast, the co-addition of citric acid did not increase the efficacy of copper.
D D Nicholas, T Schultz


A test method to simulate above-ground exposure
1978 - IRG/WP 2112
The simulated above-ground exposure technique described is worthy of consideration as a simple procedure to determine the relative decay resistance of preservative-treated wood exposed to a moderate decay hazard. The method may readily be modified to allow testing of other materials such as plywood by simply enlarging the slots cut in the modified feeder strips. The method by no means completely simulates the conditions that exist in timbers exposed out of ground contact, nor does it simulate the natural process of infection, but it does provide lower toxic thresholds and allow reassessment of relative performance of preservatives under test conditions less severe than those of soil-contact exposures. A fully acceptable test procedure will be available only when a clear understanding is gained of the decay process in timbers and commodities exposed out of ground contact.
J A Butcher


Evaluation of teak sawdayst Tectona grandis L Fil as a potential source to obtain a natural wood preservative in Colombia
2004 - IRG/WP 04-30356
Plantation Teak (Tectona grandis L. Fil) has been tested as a possible source of natural wood preservatives due to the known excellent durability of old-growth teak wood. Field tests (ground proximity termite and above ground simulated decking exposures) were established in Colombia in April 2003 at two different test sites with different climates (Tropical Dry and Rain forest). Teak heartwood extracts were obtained using Soxhlet extraction with chloroform-methanol and methanol-ethanol as solvents, for two different mixtures at three different concentrations. Sapwood stakes of Patula pine (Pinus patula) and Globulos eucalyptus (Eucalyptus globulus) were vacuum pressure impregnated with these extracts, and control stakes were impregnated with CCA Type C and ACQ Type D at two nominal retentions (1 and 4kg/m3). The test sites have been found to be very active for both decay and termites. After only 9 months exposure termite attack has been observed from four species (Nasutitermes, Heterotermes, Triangularitermes, Velocitermes), and several basidiomycetes fungi have also been isolated from the test samples (Trametes, Schisophyllum, Poria). The results show that up to 100% of the samples have been subject to fungal attack, although in most samples only superficial trace attack has occurred in the exposure period. In contrast, termite attack has been rapid, primarily on the eucalyptus samples, which are suffering substantial degradation.
A Castillo, Y Cabrera, A F Preston, R Morris


International comparison of three field methods for assessing the in-ground resistance of preservative-treated and untreated wood to termites and fungal decay – Summary of observations after five years
2003 - IRG/WP 03-20261
Results are presented from a five-year study conducted in five locations in Australia, Thailand and the USA. Three methods of exposure were assessed (below-ground, graveyard and ground contact) for evaluating the in-ground termite and decay resistance of Pinus radiata D. Don sapwood stakes that had been vacuum pressure impregnated with CCA (Type C) and ACQ (Type D) each at two nominal retentions (2 and 4 kg/m3), and of outer heartwood stakes from five trees of the durable North American Baldcypress, Taxodium distichum (L.) Rich. The termite attack and fungal decay ratings, based on the loss of cross section of the stakes, declined more rapidly at the three tropical sites in southern Thailand (Phuket) and in northern Australia (Darwin) compared to the two more temperate sites in southern USA (Gulfport, Mississippi) and southern Australia (Griffith, New South Wales). Depending on the type of preservative treatment (detailed for termites only) the three different assessment methods yielded either similar trends (ACQ 2 kg/m3; baldcypress) or outcomes varied with site and method (CCA 2 kg/m3; CCA 4 kg/m3) or the three assessment methods could be ranked from most to least effective in the same sequence across all sites (ACQ 4 kg/m3). Treatments or type of timber elicited different responses from the local termite fauna (from readily contacted by termites to avoidance). These responses can be modified by the way specimens are presented to termites. Average [n = 15] termite attack ratings (1st value Australian, 2nd value ASTM rating) after 5 years in the tropics (T) and non-tropics (NT) were: CCA 2 kg/m3 T = 4.3/6, NT = 6.7/8; CCA 4 kg/m3 T =5.5/7, NT = 7.4/9; ACQ 2 kg/m3 T = 4.4/6 , NT = 6.9/9; ACQ 4 kg/m3 T = 5.4/7, NT = 7.1/9. Baldcypress was more durable in the USA and Thailand (slight attack) and least durable against Mastotermes darwiniensis Froggatt in Australia (moderate attack). Fungus decay ratings (1st value Australian, 2nd value ASTM rating) after 5 years were: CCA 2 kg/ m3 T = 5.1/7, NT = 7.9/9; CCA 4 kg/m3 T = 6.1/8. NT = 7.8/9; ACQ 2 kg/m3 T = 5.2/7, NT = 6.7/9; ACQ 4 kg/m3 T = 5.6/8, NT = 7.7/9. Baldcypress results varied with source tree and test method.
M Lenz, J W Creffield, T A Evans, B M Kard, C Vongkaluang, Y Sornnuwat, A F Preston


Tropical In-Ground Durability of Structural Sarawak Hardwoods Impregnated to High Retention with CCA-salts, CCA-oxide and FCAP after 20 Years Exposure
2005 - IRG/WP 05-30384
Statistical analysis (ANOVA) was conducted on durability (termite and decay combined) rating data collected over 20 years exposure period of over 140 species of Sarawak timbers with altogether 30,000 stake specimens, at the Forest Department’s Sibu “graveyard” stake test sites from 1977. About 20 replicated stakes were pressure-treated to refusal with 10% g/ml concentration of up to 3 CCA-salt formulations and 1 CCA-oxide product and FCAP were visually evaluated every 6 months according to the 5-point ASTM D1758 durability rating scale, and the treated durability results reported in this paper are between 5 and 20 years exposure. The analysis was confined to 7 relatively high density hardwood species that are regarded suitable for in-ground structural use (ie, basic density >600 kg/m3), and had achieved a minimum preservative retention of 16 kg/m3 (as required for CCA-salts) but up to 48 kg/m3 retention. The results revealed that the in-ground durability of treated wood decreased usually after 5 years to poor-to-moderately durable levels with CCA-salts, moderate-to-high durability with CCA-oxide, but failed with FCAP after 20 years. CCA-oxide treated hardwoods out-perform the CCA-salt treated counterparts despite their relatively similar retention and “over-treatment factor”. The non-leach-resistant FCAP is clearly unsuitable as an industrial used in-ground wood protectant.
Wang Choon Ling, A H H Wong


Dominant genera of fungi isolated from the surfaces of Sugi (Cryptomeria japonica D. Don) heartwood lumbers exposed at six test sites from northern to southern regions of Japanese islands
1999 - IRG/WP 99-10304
The surfaces of wood materials are disintegrated not only by sunlight and rainwater but also by microbes when exposed above ground condition. This paper deals with the investigation of fungi isolated from the surfaces of Sugi heartwood lumbers (W100 by T10 by L300 mm) exposed at an angle of 45° without ground contact for 16 months at the six test sites from northern to southern regions of Japan. The parasites were collected from the surface using the Sellotape. Isolation medium used was PDA including 100 ppm tetracycline-hydrochloride to suppress the growth of bacteria. Identifications were microscopically conducted using a slide culture technique. Dominant genera isolated were Aureobasidium and Nigrospora regardless of the test site as well as climatic condition.
S Doi, M Mori, M Kiguchi, Y Imamura, M Hasegawa, S Morita, S Nakamra, Y Kadegaru


The ground proximity decay test method
2000 - IRG/WP 00-20205
A decay field test method, which has been recently proposed for the standardization by the AWPA, is described for evaluating the relative performance of wood samples in a severe above ground situation exposed to the weather. Data is presented on the relative performance of untreated control samples and standard preservative systems exposed at the same site at different time periods, or at different test sites with the same test materials using this test methodology. Comparison data including this method with other standardized test methods is also included. The experimental data collected during last 13 years show that the method provides a viable and consistent methodology for generating results representing the worst above ground exposed situation that might be encountered during service.
A F Preston, P J Walcheski, K J Archer, A R Zahora, L Jin


Accelerated testing for out of ground contact using natural biological preconditioning: Part 2
1997 - IRG/WP 97-20108
Small blocks of scots pine sapwood were treated, buried in vermiculite and exposed to natural microbial colonisation during outdoor exposure prior to laboratory decay testing. An EN 84-type leach trial was carried out on unexposed samples. Periodic microbial isolations, moisture content, permeability and weight loss tests were also conducted. The experiment ran for 12 months. The colonisation of the miniblocks by micro-organisms was rapid and different patterns of colonisation were observed for differently treated miniblocks. The dominant organisms throughout were Alternaria sp., Fusarium sp., Curvularia sp., Aureobasidium pullulans, Phialophora sp. and bacteria. Weight losses of 10% occurred in the field by 12 months with untreated samples. DDAC- and TnBTO-treated miniblocks (at the recommended commercial retention) had weight losses of 7% and 8% respectively. ACQ treated samples at this retention had the lowest weight losses at only 1.5%. Of the treated samples, TnBTO-treated blocks had the most rapid rate of weight loss and also the fastest increase in permeability. TnBTO-and DDAC- treated samples had equivalent final permeabilities, at double the value of the ACQ-treated blocks. The decay trial indicated that this natural pre-exposure method was very severe with reduced performance of all treatments in the monoculture Basidiomycete tests after 12 months of pre-exposure. The comparative leaching trial showed that the failure of the preservatives was not due only to severe leaching in the test system. The white rot decay test indicated that at all retentions TnBTO- and DDAC-treated miniblocks had reached over 3% weight loss by 3 months pre-exposure but for ACQ this weight loss was not reached until 12 months. In the brown rot test at all retentions of TnBTO and ACQ weight losses of over 3% were reached by 3 months and for DDAC by 6 months.
S Molnar, D J Dickinson, R J Murphy


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