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Proposed method for out-of-ground contact trials of exterior joinery protection systems
1981 - IRG/WP 2157
Methods for testing the efficacy of preservative treatments for exterior joinery are described using the format of a European Standard. Commercially used treatments applied to jointed test units (L-joints) which are then protected by conventional finishes are exposed to normal outdoor hazards out of ground contact. Assessment is made a) by determining eventual failure through decay and b) by destructive examination of replicate treated and untreated units, after increasing time intervals, rating comparative performance in terms of wood permeability increase and the progress of microbial colonisation.
J K Carey, D F Purslow, J G Savory


Wood preservatives: Field tests out of ground contact. Brief survey of principles and methodology
1976 - IRG/WP 269
This paper contains the following spots: 1.: The general need for field tests. 2.: Interests and limits of field tests in ground contact. 3.: Various methods in use for out-of-ground contact field tests. 4.: Fungal cellar tests are they an alternative to above-ground decay exposure tests? 5.: Conclusions.
M Fougerousse


Forest products laboratory methodology for monitoring decay in wood exposed above ground
1995 - IRG/WP 95-20074
Research at the Forest Products Laboratory on the durability of wood in service has included a full complement of laboratory and field tests. In this report, we present a review of past and current methods used to evaluate the condition of preservative-treated wood exposed above ground. Current protocols are described for tests on wood packaging, roofing, and dimension lumber.
R C De Groot, T L Highley


Field trials on preserved timber out of ground contact
1978 - IRG/WP 3154
This report describes two different field trials studying the performance of preservative treatments on timber exposed to the weather, but above the ground. Results are presented on the protection afforded against decay, and on the efficiency of water-repellent preservative treatments in controlling the uptake of moisture by the timber. Proposals for a standard field test system are briefly discussed.
D F Purslow, N A Williams


A note on testing the efficacy of wood preservatives above ground
1995 - IRG/WP 95-20078
A number of test methods have been used to evaluate the performance of wood preservatives in above ground situations. These have included EN 113 tests following natural exposure weathering (NEWT), L-joint or T-joint tests, lap-joint tests, and decking tests. A new test referred to as the A-frame test has been developed and is under evaluation. This is based on a sandwich-type test in which a thin (3.5 mm) sample is exposed outdoors between two untreated samples on a rack or A-frame. The advantages and disadvantages of these types of tests are discussed in a short note.
G R Williams, J A Drysdale, R F Fox


The rate of redistribution and loss of leachable preservatives under service conditions
1993 - IRG/WP 93-30026
This paper describes experiments carried out to determine patterns of preservative redistribution and any associated losses which occur when wood containing unfixed water-soluble wood preservatives is exposed to service conditions where leaching is possible. Scots pine sapwood treated with disodium octaborate was used as a model system. Results are recorded and discussed for trials representing painted joinery out of ground contact and unpainted stakes half buried in the ground. The results indicate that in the painted samples out of ground contact the water-soluble compound was redistributed longitudinally and away from the joint zone during the first months of exposure, although little redistribution occurred laterally. No difference in redistribution patterns could be associated with paint type. Ground contact stakes showed a loss in the water-soluble compound of about 40% in the first six months exposure. Most of this appeared to occur from the surface zones of the stake exposed to the weather, particularly from the extreme top. In addition, the compound appeared to migrate upwards from the below-ground portion of the stake to the above-ground portion. These results provide new information on the extent of movement of water-soluble preservatives in painted, jointed timber out of ground contact and in unpainted timber in ground contact. It is concluded that the long-term significance of the observed redistribution effects for painted joinery should be evaluated to confirm that there is no likelihood of shortcomings in performance in practice. For the ground contact situation, results confirm that rates of redistribution and loss are high enough to indicate inappropriateness of such materials for practical use without associated technologies to reduce mobilities.
R J Orsler, G E Holland


Above ground testing of wood preservatives - some experiences from Sweden
1995 - IRG/WP 95-20079
Field stake tests for the evaluation of wood preservatives have been used for more than 50 years in Sweden. In the Nordic countries a system for approval of wood preservatives, which includes field test, has also been in operation for more than 25 years. This system has been described in an IRG Document by Henningson & Jermer (1988). The Nordic system is now in a process of harmonization with the European system based on CEN's hazard classes (Henningsson & Jermer, 1994). Strangely enough, field testing for approval purposes in Sweden and the Nordic countries has only been done with stakes in soil contact. In earlier days approval requirements for a preservative for above ground situations was determined on the basis of results obtained in stake tests. Subsequently the Nordic approval system accepted laboratory decay tests as an approval basis for above ground preservatives. The European Standard EN 113 or comparable methods were allowed. This means that wood preservatives for above ground use could be approved after only laboratory tests, which - as a matter of fact - was against the generally accepted testing philosophy in these countries. The absence of standardised methods for field testing of above ground preservatives, however, does not necessarily mean that such tests have not been performed in Sweden. In the following some examples of above ground testing will be given. Although these tests may not particularly have been designed for testing the efficacy of wood preservatives, they may be of interest in discussing methodology and they may be imptortant in special cases. The examples are: Test with plank pieces; Window-frame corners; Organotin degradation test; tests with piled samples; tests about the natural durability of wood panels.
B Henningsson, Ö Bergman


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


Performance of treated spruce in Canadian field test sites
1989 - IRG/WP 3506
Spruce material under test in Canadian field test sites is performing better than anticipated. From the comparison of the performance of spruce treated with various preservatives, it appears that penetration may be far more important on durability performance than the preservative itself or the retention of preservatives in the wood. However, there is still insufficient data on the influence of penetration on the performance of treated spruce. As data for species other than white spruce and data for sawn material is also incomplete, spruce cannot be accepted by the Canadian standards at this time.
J P Hösli, E E Doyle


The use of zirconium as an inert fixative for borates in preservation
2001 - IRG/WP 01-30256
Stand-alone borates have been used in internal protected situations as wood preservatives for about 60 years. They have not been deemed acceptable for external situations because of their leaching characteristics. Work carried out to reduce the leachability of borates has been reviewed briefly here, and a specific fixation agent based on zirconium has been tested in standard leaching and decay tests. It was found that the performance of zirconium could be optimized for fixation at specific drying temperatures and at higher formulation pH. Using sufficient quantities of ammoniacal zirconium carbonate and potassium zirconium carbonate such formulations are then able to pass both Standard European and American Wood-Preservers' Association methods designed for testing exterior wood preservatives. Formulations based on borate with a zirconium additive are probably suitable for use in exterior above ground and possibly ground contact situations. As only initial indicative tests have been carried out so far, further testing with a range of wood destroying organisms and field tests should be carried out to evaluate this system further.
J D Lloyd, J L Fogel, A Vizel


Long term performance of CCA preservatives in ground contact
2000 - IRG/WP 00-30223
Copper-chrome-arsenate (CCA) preservatives have been use extensively in New Zealand since the mid-1950s for a wide range of ground contact uses, radiata pine being the main species treated. They have been the subject of a comprehensive field testing programme in up to five sites in New Zealand, the earliest tests being established in 1955. Main factors affecting performance have been formulation type, test site and test specimen size. In nearly all tests where efficacy of CCA has been compared with other preservatives, CCA has been more effective in controlling decay, particularly on drier sites. In a warm and wet site (annual rainfall 2,000 mm) where soft rot and brown rot predominate, there has been very little difference in performance between CCA and other multi-salt formulations, but in a very wet site (annual rainfall >3,500 mm) CCB and CCP have out-performed CCA.
M E Hedley, D R Page, B E Patterson


Performance of copper-based wood preservatives in above ground and ground contact tests
1994 - IRG/WP 94-30057
The relative performance of a range of copper-based wood preservatives was compared using above ground and ground contact procedures. The data, accumulated after several years' testing, show that on an equivalent active ingredient basis, differences in performance of the preservative systems tested can vary quite markedly. The contribution of co-biocides to the overall performance of these copper-based systems is discussed.
A F Preston, K J Archer, L Jin, W Metzner, D Seepe


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


Above-ground field tests undertaken in New Zealand
1995 - IRG/WP 95-20063
In addition to "standard" L-joints, above-ground test material exposed at the NZ FRI test site includes treated and untreated decking units, Y-joints, fence battens and weatherboards either with or without additional protection from surface coatings. The latter tests bridge the gap between "model" test assemblies, such as L-joints, and services tests. Most tests are of preservative-treated radiata pine using proprietary formulations which were approved for above ground use at the time when each test was established. Other tests are natural durability tests to determine the suitability of those species, in terms of durability and mechanical properties, for above ground use without preservative treatment. The first tests were established in 1952 and results from those and subsequent tests have been used during periodic amendments to NZ wood preservation standards and specifications. The purpose of the different tests is described as well as pertinent results from them to illustrate their value.
M E Hedley, D R Page, J B Foster, B E Patterson


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 soil-less test of treated wood
1978 - IRG/WP 2105
The objective of this work is to devise an accelerated test for preservatives to be used in places away from soil contact. There may be compounds or mixtures which will protect wood or wood derived materials from decay in such articles as sash and doors, boardwalks, steps, laminated arches and the like, and possess properties that make them preferable to the heavy-duty preservatives used for poles, cross-ties or items to be used in soil contact. This experiment is an attempt to evaluate a test thought to be more in keeping with practice than the soil block test. Wood with a series of treatments is exposed in close contact with wood undergoing active decay by a known fungus (basidiomycete). Lack of transfer of decay would indicate that the treatment protects the wood. Use of test pieces of size comparable to use conditions and of non-sterile conditions approaches practicality more so than what is followed in the soil-block test.
E A Behr


Ammoniacal wood preservatives for use in non-pressure treatment of spruce and aspen poplar. Part 2
1984 - IRG/WP 3274
A series of thermal diffusion treatments were carried out on unseasoned white spruce (Picea glauca (Moench) Voss) lumber and air dry aspen poplar (Populus tremuloides Michx.) timbers using an ammoniacal copper arsenate wood preservative. Under the specific conditions described, certain charges of lumber met the present Canadian Standards Association Wood Preservation Committee's requirements for wood in ground contact, having 10 mm penetration and 6.4 kg/m³ loading. The average preservative penetration in the heartwood of white spruce lumber ranged from 6.3 mm for charges of nonincised lumber to 13.9 mm for incised lumber. Preservative retention in the treated area was above 6.4 kg/m³ in four of the five charges of spruce lumber treated by this method. Aspen poplar timbers treated by thermal diffusion averaged 16.4 kg/m³ oxide retention. Post-treatment procedures such as close piling the lumber resulted in material with cleaner surfaces and more even penetration of preservative components.
C D Ralph, J K Shields


Working plan: Second international collaborative field trial
1995 - IRG/WP 95-20056
This paper describes the scope, objectives, and approaches to be used in the second international collaborative field trial approved by the Scientific Programme Committee for partial funding in 1994. The trial is designed to develop a broad data base on causal mechanisms, interactions, and factor affecting the performance of treated wood in ground contact. The trial encompasses 12 different field test sites representing all continents except Antarctica. Preservatives were chosen to represent new technologies and include oilborne, waterborne copper-organic, and water-dispersible systems. CCA is used as the reference system. Task forces to research the following areas are described: accelerated soilbed testing, decay types/modes of failure, preservative depletion, abiotic factors, and copper tolerance.
H M Barnes, T L Amburgey


Five years field test results for CCA and ACQ preservatives fixed in different climates
1999 - IRG/WP 99-30208
During assessment of the ground contact stakes in the Norwegian test field, we have found that very often the first visual rot attack is in the zone of the stakes were the stakes have been in contact with each other during the fixation. These parts are usually light green, caused by the lack of light during fixation, compared to the rest of the stake surface, which has a darker colour. To investigate if light on the stakes during fixation can affect the durability of the treated wood, we started a test five years ago. CCA and ACQ treated stakes were tested according to EN 252. The stakes were treated with two retention of each salt, one for the Nordic Class A (HC 4) and one for the Nordic Class AB (HC 3). Before exposure they were fixed in 7 different climates: 1) "Normal" fixation (60% RH and 25°C), light day, dark night for 7 days 2) "Normal" fixation without light for 7 days, 3) "Normal" fixation with UV-Iight 24 hours for 7 days, 4) "Stem" fixation 95% RH and 90°C, for 2 hours, 5) "Cold" fixation 50% RH and 10°C, for 30 days, 6) "Dry"fixation 10% RH and 50°C, for 24 hours, 7) "Wrapped" fixation, i.e. each stake packed in plastic foil, 50°C and no light for 24 hours. The colour of the stakes varied from light green to black, depending on the fixation climates. The rate of decay after 5 years in field test shows no big differentiation based on the fixation in different climates, even for the lowest retention.
F G Evans


Performance criteria for approving new wood preservatives for ground contact
1994 - IRG/WP 94-20021
Protocols for testing novel formulations prior to approval or registration as wood preservatives are being developed in a number of countries, e.g. Australia, New Zealand, USA. One aspect which must be addressed is the effectiveness in tests relative to that of currently approved formulations which would be acceptable to approving authorities. It is assumed that natural exposure testing is a prerequisite procedure before application for approval is sought and that a minimum exposure period of five years is required. Using CCA as a reference formulation and combined field test stake results from other copper-chrome-(non-arsenical component) formulations, performance criteria have been developed for novel formulations where approval for use in ground contact is sought.
M E Hedley


Performance of preservative-treated timber commodities in above-ground service tests
1995 - IRG/WP 95-20064
Service tests established by NZ FRI are of commodities where treatment has been undertaken in commercial plants and although such data as preservative uptake of individual items is recorded and sample analysis undertaken, material is usually "run-of-mill" for the commodity being treated. The NZ FRI Service Test database includes a wide range of preservative/species combinations in virtually all above ground commodities where timber or plywood is used. They include complete bridges, domestic and commercial building components (sheathing, framing, window joinery, decking, roofing shingles), log houses, cross-arms, cooling towers and geothermal steam bore silencers. Often, such as in glue-laminated bridge components, these tests are the only unequivocal way the fitness for purpose of particular species/preservative combinations can be tested. Prosedures for establishing the programme and maintenance of the database are given with a summary of current tests and a selection of pertinent results from them.
M E Hedley, D R Page


Three-year field trials of polymeric formulations which provide a new basis for the invention and design of non-toxic wide-spectrum wood preservatives
1994 - IRG/WP 94-40029
Three types of non-toxic polymeric formulations invented using a new approach to wood preservation were challenged with termites and fungi in three-year ground-contact field trials in the sub-tropical climate of Natal. These formulations were copper soaps of carboxylic acid groups of unsaturated fatty acids of waxes and edible vegetable oils; of resin acids of rosin, and, of synthetic unsaturated polyester resins. The formulations self-polymerise within lumena of wood elements after pressure-impregnation and also co-react with carbon-carbon double bonds and aromatic nuclei of lignin. The biocidal mechanism is based on the release of copper by hydrolysis under humid conditions and on the reformation of the same bond on redrying of the treated timber in service. All formulations tested were effective and durable. Rosin formulations at retentions of 0.91 kg/m³ and polyester formulations at retentions as low as 0.4 kg/m³ each out-performed creosote at 37.5 kg/m³.
A A W Baecker, A Pizzi


The use of organic wood preservatives in ground contact and the suitability of laboratory test procedures to determine their efficacy
1999 - IRG/WP 99-20175
Organic fungicides, such as propiconazole, have proven to be highly effective when used as a co-biocide in recently developed wood preservative formulations. They have however been ineffective when used as a stand alone preservative, particularly when used in ground contact (European Hazard class 4). Previous research, using the test methods of ENV 807 (1993), provided conflicting evidence regarding the efficacy of propiconazole when used in a ground contact situation, with the preservative appearing effective when tested using the vermiculite test and ineffective when using soil burial. This paper considers the use of the existing methods of this European Standard for use in the research and development of organic fungicides, and compares alternative micro-fungal spore combinations to that stated in EN 807 (1997) with the aim of improving test performance.
I J Herring, D J Dickinson


Leaching of components from CCF treated timber in ground contact
1998 - IRG/WP 98-50108
In order to investigate the depletion of different CCF-salts during service small stakes (10*10*450mm³) were treated with five water-borne wood preservatives and after fixation brought into ground contact for several years. After failing some of the broken down stakes were used to determine the remaining concentration of relevant ions and their distribution in different segments of the stakes. As expected the content of the components in the stakes decreased with time. Furthermore the results show that the remaining concentration of copper, chromium and fluorine differ depending from the wood preservative used and from the position of the segment in the stake. Only up to 20% of the fluorine was found in the stakes whereas up to 100% of chromium or copper was left. The highest F concentration was determined in the samples when hexafluorosilicate was used in the formulation of the water-borne wood preservative. On the other hand the results show clearly that irrespective of the ion investigated, by far the largest amount was analysed in the fracture zone.
E Melcher


Bethoguard; A new wood protecting fungicide for use in metal free ground contact wood preservatives
2002 - IRG/WP 02-30301
Research has identified the limitations in both the spectrum of activity and permanence of organic biocides placed in wood in high hazard environments, particularly in the absence of heavy metals such as copper. More specifically, the control of soft rot decay in wood in soil contact has proven to be most problematic. The new organic biocide, Bethoguard; an oxathiazine, has demonstrated excellent potential for these end uses and has shown particularly good soft rot performance in both laboratory and simulated field exposure evaluations. During this research, emphasis has been placed on the inclusion of additional active ingredients necessary to complete the spectrum of activity towards other wood degrading organisms such as white rot and brown rot. This paper presents an overview of this molecule as a new wood preservative and presents preliminary results from laboratory screening procedures.
S C Forster, G R Williams, M Van Der Flaas, M Bacon, J Gors


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