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Collaborative tests on the influence of solvent and drying method on the toxic limit of wood preservatives against Basidiomycetes
1974 - IRG/WP 248
Seven institutes from five countries, Austria, England, France, Germany and the Netherlands have collaborated in a study on the influences of solvent and drying method on the toxic limits of wood preservatives against Basidiomycetes tested according to the agar-block method. Two preservatives, a 25% pentachlorophenol-concentrate and tributyltinoxide were applied to pine sapwood and beech and tested against Coniophora puteana. The preservatives were diluted with either acetone. benzene, chloroform or xylene. Slow drying in vapour of the solvent was used for all solvents. In addition quick drying was used for benzene and chloroform and freeze drying for benzene. The results were not conclusive regarding any influence of the solvent and drying method on the toxic limit. There was a trend that the toxic limit of the pentachlorophenol concentrate is decreased by the use of acetone as solvent. An influence of acetone on the toxic limit of tributyltinoxide could not be stated. The results regarding an influence of the drying method on the toxic limit of the preservatives were variable. There is some evidence that the toxic limits are lowered by freeze drying. As this effect is not present in all cases, the differences in the established toxic limits are probably due to normal variation in results and not associated with the drying method.
T Hof


The effect of preservative distribution in small blocks of Pinus sylvestris on the toxicity of tributyltin oxide to Reticulitermes santonensis Feytaud
1971 - IRG/WP 206
Small blocks of Pinus sylvestris (50x25x15 mm³) were treated by a full-cell method with various concentrations of tributyltin oxide in benzene. Replicate blocks were then freeze dried, rapidly air dried or slowly air dried and exposed to surface attack by the subterranean moistwood termite Reticulitermes santonensis Feytaud. At all concentrations it was found that the freeze-dried blocks were more heavily attacked than the air-dried ones, and that a threshold value determined in the normal way using air-dried blocks could be much underestimated. This agrees with what one would expect from the uneven distribution of preservative produced by air drying compared with the uniform distribution obtained by freeze drying. The results with slow air drying were in between those obtained from the other two methods. Further work is required to check the value of this method.
M P Levi, D N R Smith


Effect of post-treatment drying schedule on the modulus of elasticity of CCA-treated southern pine dimension stock using nondestructive methods
1987 - IRG/WP 3413
This paper describes the results from the nondestructive testing for modulus of elasticity (MOE) of southern pine (Pinus sp.) 2 x 6's treated with chromated copper arsenate and redried using three commercial kiln schedules. The data indicate that redrying CCA-treated southern pine dimension stock treated to above-ground retentions (4 kg/m³) has no deleterious effect on the MOE, regardless of the kiln schedule employed. These data tend to confirm conclusions of other work with redrying of treated pine which indicate that MOE is not affected by the redrying schedule.
H M Barnes, S Moore


Co-operative tests concerning the influence of solvent and drying method on the toxic limit of wood preservatives against Coniophora cerebella
1972 - IRG/WP 216
In the working group II of the IRG it was agreed that more knowledge was necessary concerning the influence of the solvent on the toxic limit of organic solvent types of wood preservatives against Basidiomycetes. A test program was drawn up and after discussion in the mentioned working group the final program was accepted by the co-operating institutes in 1969. In the test program two fungicides, a pentachlorophenol concentrate and tributyltinoxide, solved in four different solvents were enclosed. Considering that an influence of the kind of solvent could coincide with the rate of evaporation thereof from the test blocks, also different drying methods were included for some solvents. Preliminary results of these co-operative tests have been given in a report presented on the meeting of the IRG Working group II in November 1971 in Brussels. At that time the tests were not yet completed and the results then available were not worked out in details. The complete test program is now finished and the results are given in this report.
T Hof


Survey of practical methods for conditioning of forest products before preservative treatment
1971 - IRG/WP 39
The seasoning of forest products is undertaken for a wide range of end uses and is becoming increasingly required for applications and building construction and secondary manufacturing industries. A wide range of applications of new technology and specifically required seasoning schedules is being actively developed for such requirements, but less attention has been given to the means by which wood can be prepared for successful preservation treatments by seasoning or more general conditioning treatments. Much of the knowledge of the practical means of achieving good treatments through prior seasoning and conditioning resides in the skill and experience of larger treating companies. Although many of the pertinent means of achieving proper pretreatment seasoning are mentioned in important sets of standards, such as those of the American Wood Preservers Association (AWPA) and the Canadian Standards Association (CSA), it is often necessary for the consumer of treated forest products to develop the appropriate means of seasoning for his special case through reliance on the knowledge of the treater. In the case of a large consumer, such as the major utilities, there is often his own body of experience gained through the activities of a research and development group.
J Rak, T S McKnight


Solvent drying and preservation of timber
1977 - IRG/WP 381
Processes which combine drying and preservation are first reviewed. Some preliminary experiments are then described in which blocks of green Sitka spruce sapwood were immersed, in a solution of tributyltin oxide (TBTO) in methanol at 60°C. Satisfactory penetration of the preservative and exchange of methanol and water occurred in a few hours. The methanol was removed rapidly from the wood by evaporation. Satisfactory penetration of TBTO into initially methanol-saturated samples occurred in a similar period. The factors influencing. such treatments are discussed. High initial moisture content of the wood and a high operating temperature are particularly desirable. Some aspects of the possible commercial operation of the process are discussed.
J A Petty


Biological screening assays of wood samples treated with creosote plus chemical additives exposed to Limnoria tripunctata
1980 - IRG/WP 408
Laboratory methods for exposure of treated wood coupons to Limnoria tripunctata are described. Chemical additions to creosote were screened using this method. Three pesticides, Endrin, Kepone, and Malathion proved particularly effective. The addition of varying percentages of naphthalene to creosote using several treatment methods are currently being assayed. Results to date show that the coupons treated by the empty cell method have better performance than those prepared by the toluene dilution method. The naphthalene coupons treated by the full cell method show no attack after six months' exposure.
B R Richards, D A Webb


Field test evaluation of preservatives and treatment methods for fence posts
1985 - IRG/WP 3347
This work presents the field test results after fifteen years exposure of Eucalyptus saligna fence posts treated with six different preservatives and five treatment methods. All the combinations with oil-borne preservatives presented the best results and among the waterborne preservatives, the fence posts treated by immersion method were with the lowest performance in the field test.
G A C Lopez, E S Lepage


The applicability of life cyle analysis and alternative methods in the wood preservation industry
1994 - IRG/WP 94-50023
In the Netherlands, several case studies have been performed using the life cycle analysis method (LCA). This type of research is aimed at an inventory and classification (sometimes including also evaluation) of the environmental impacts of a product, from the raw material to waste stage ("cradle to grave" approach). In a LCA each environmental impact is assessed in terms of, for example, mass of raw material use (kg), energy consumption (MJ), emissions (COx, NOX, SOx, etc.) and final waste (in kg). The critical point in an LCA is the definition of comparable "functional units" for similar products made of different materials with different service lifes. As the LCA method has often proved to be very complex, lime-consuming, expensive and difficult to interpret and translate into practically usefull results, alternative methods are developed. Three methods are described and compared on the basis of various examples. It is hoped that this may be of use as a starting point for further discussion on the suitability of applying the LCA on (preservative treated) timber products.
P Esser, J Cramer


Influence of different fixation and ageing procedures on the leaching behaviour of copper from selected wood preservatives in laboratory trials
2003 - IRG/WP 03-20264
The paper focuses on the role of different parameters, such as fixation, sample size, wood species, and leaching in internationally standardized ageing procedures for wood preservatives from Europe, Japan and the United States. The leaching protocols used were EN 84, JIS K 1571 and AWPA E11 protocols. The wood species were Scots pine, Sugi and Southern Yellow Pine respectively. Three types of commercially important copper-based wood preservatives were used as model formulations, namely copper/copper-HDO, ammoniacal copper/quat and CCA. The most important factors determining the extent of copper leaching in the different lab trials were the sample size (volume/surface ratio) and the fixation conditions prior to leaching. On the other hand, the wood species and the leaching protocol itself were found to have only minor influence on the copper leaching rate in the test methods included in this study.
J Habicht, D Häntzschel, J Wittenzellner


Strength loss associated with steam conditioning and boron treatment of radiata pine framing
1987 - IRG/WP 3438
The combined effect of included defects and wood moisture content on the strength loss of second rotation radiata pine framing following conventional steam conditioning is investigated. The green Modulus of Elasticity (MOE) is reduced by approximately 13% after steaming. When dried after steaming, however, neither the MOE nor MOR is significantly different from unsteamed dried controls.
M J Collins, P Vinden


Testing of wood preservatives against marine borers (Part 1). Method of testing wood preservatives against marine borers (Part 2)
1971 - IRG/WP 37
P C Trussell, C C Walden


The use of pressure cycling to improve heartwood penetration in Pinus radiata (D. Don)
1995 - IRG/WP 95-40050
This study investigates the effect of cycling pressure on the treatability of radiata pine heartwood. The results indicate that liquid penetration into the heartwood is affected by the preconditioning method used and pressure treatment time. There is no significant improvement in the penetration of Pinus radiata (D. Don) heartwood when a cycling or pulsation process is used.
P R S Cobham, P Vinden


Low temperature drying conditions of Pinus radiata wood for avoiding internal stain
1989 - IRG/WP 3507
It has been observed that, if in little sawmills, timber is dried with a low temperature schedule, it arrives at destination with internal sapstain besides of superficial mould. In this study, the lowest drying temperature at which wood should be exposed for sterilization, which results to be 52°C, is searched. It is not possible to avoid entrainment of pentachlorophenol, even though a waiting period of 72 hours after dipping the wood in a pentachlorophenate/borax solution before drying is considered. The residual content of pentachlorophenol in wood should be at least 400 µg/cm² or the moisture content less than 23% for avoiding the development of mould.
M C Rose


Comparison of Different Methods for Assessing the Performance of Preservatives in the BAM Fungus Cellar Test
1998 - IRG/WP 98-20149
The fungus cellar test is a common means to get reliable data on the long term performance of treated wood in soil contact. A constantly high humidity and a suitable of water holding capacity for a range of micro-organisms provide high decay rates in untreated wood and produce intensive microbial pressures on wood treated with biocides. Presently a range of biocides are under test in the BAM fungus cellar and the results will be presented for the following types of biocides: Tebuconazole in combination with copper and boron (5 years fungus cellar), quats with copper and boron (5 years fungus cellar) and Cu-organic compound combined with copper and boron (3 years fungus cellar). Figures will be shown on the development of the Modulus of Elasticity (MOE) over the years and on an assessment of the stakes according to EN 252.
I Stephan, M Grinda, D Rudolph


Report on the activities of the European Standardization Committee CEN/TC 38 'Methods of Testing wood preservatives'
1980 - IRG/WP 279 E
G Castan


Respiration methods used to follow the decay of wood and the toximetric evaluation of wood preservatives
1975 - IRG/WP 249
When wood is attacked and decayed by fungi, wood substance and oxygen (02) are consumed, while carbon dioxide (CO2), water and heat are liberated. Early in the 1960's workers from England, Canada and Sweden began studying CO2 evolution, with respect to decay and its control using chemical preservatives, while in Germany and the USA O2 utilization was being similarly examined. Oxygen consumption measurements during the decay of wood were made mainly using pressure differential closed systems and were shown to be reasonably sensitive and a suitable reflection of the rate and extent of decay. Carbon dioxide measurements were made using titration, conductivity and gas-chromatographic methods. The last method appears to be the most useful, being applicable to open and closed systems, flexible in application, very sensitive over a thousand-fold concentration range change without switching, and easily automated. Its application to evaluating the toxicity of wood preservatives has been intensively studied and shown to give chemical toxic thresholds after only one third of the normal incubation time, which are similar to those based on the much longer conventional weight loss method.
R S Smith


Durability of pine modified by 9 different methods
2004 - IRG/WP 04-40288
The decay resistance was studied for pine modified by nine methods of wood modification: 1) Acetylation, 2) Treatment with methylated melamine resin (MMF), 3) Acetylation followed by post-treatment with MMF-resin, 4) Thermal modification, 5) Furfurylation, 6) Maleoylation (using water solution of MG or ethanol solution of maleic anhydride), 7) Succinylation, 8) NMA-modification and 9) modification with reactive linseed oil derivative (UZA), Wood blocks of Scots pine (Pinus sylvestris L.) sapwood were modified in pilot plants. Methods 1-5 were performed by the authors at Chalmers University of Technology or at BFH in Hamburg. Methods 5-9 were part of a European research project (the Chemowood project, FAIR-CT97-3187) and therefore each of these modifications was performed by the project participant responsible for the method. For laboratory testing in TMCs (modified European standard ENV 807) and pure basidiomycete culture bioassays, smaller test specimens were cut from the modified wood blocks. Most of the modification methods were applied on test specimens for marine field testing (EN 275) and some methods to produce mini-stakes for field tests in five Swedish fields. Some modification methods result in modified wood with poor durability, whereas other methods (acetylation, furfurylation and MMF-treatment) seem to provide excellent resistance to microbial decay.
M Westin, A O Rapp, T Nilsson


Comparison of the agar-block and soil-block methods used for evaluation of fungitoxic value of QAC and CCA wood preservatives
1994 - IRG/WP 94-20039
The modyfied agar-block and soil-block methods were used for comparing the fungitoxic value of QAC and CCA type preservatives against Coniophora puteana and Coniophora olivacea The mass loss and moisture contents of wood were analysed.
J Wazny, L J Cookson


Termite standards questionnaire survey. Second Report
1989 - IRG/WP 1395
Information contained in replies received from IRG members responding to the survey continue to be summarised. Again, highlighted in this second report are the major termite species in the various zoogeographical regions, their damage ranking to timber-in-service, the chemicals used in control methods, and the status of the termite standards in the respondent countries.
J R J French, J P La Fage


Spruce lumber treatments with ammoniacal solutions of inorganic preservatives
1977 - IRG/WP 391
As a part of our work in the Wood Preservation group at the Eastern Forest Products Laboratory in Ottawa to facilitate exploitation of spruce, which is a large timber resource in Canada, we have been studying the treatability of spruce roundwood. A report on this subject was presented to this group last year. More recently, another commodity - spruce timber - has been rapidly gaining the interest of wood treaters, mainly because of its potential use in permanent wooden foundations. We identified this trend and extended our research work to the treatability of spruce lumber.
R Rak


Borate thermal treatments
1992 - IRG/WP 92-3715
Green, partially seasoned (air-dried, steam conditioned), or kiln-dried southern pine timbers were treated thermally using 15% disodiumoctaborate tetrahydrate solution. After treatment, sections were stored under non-drying conditions to allow for diffusion. Results showed that effective treatment meeting the AWPA minimum retention (0.17 B203 pcf [2.72 kg/m³] in the outer inch) and penetration (2.5-in [64-mm] or 85% of the sapwood) could be obtained only with certain combinations of seasoning, treatment, and diffusion storage. The best results in terms of both retention and penetration were obtained with material steamed and stored prior to treatment using a 10-min hot bath time. Kiln-dried timbers could not be treated effectively. The results suggest that non-conforming treatment of green or partially seasoned timbers will require higher solution concentrations, higher hot bath temperatures, and/or longer diffusion periods to meet required standards. Results also indicated that treatment of smaller stock in dimension sizes (up to 2-in [50-mm]) should be feasible.
H M Barnes, R W Landers, L H Williams


European standardization for wood preservation
1988 - IRG/WP 2321
G Castan


Radical changes in the requirements for more safe pressure impregnation in the Nordic countries in 1988
1990 - IRG/WP 3581
After introduction of quality control schemes and standards in the Nordic countries during the seventies, the first radical change of the standards and practice of work took place after pressure from the labor unions and authorities in 1988 and 1989 in Denmark and in Sweden. A new class of preservation with less retention for out of ground contact use was introduced, fixation times were prolonged to 6 and 14 days, and branding became a requirement. At the same time, treating companies replaced CCA with arsenic-free preservatives, and started using processes for accelerated fixation. Drying of treated wood was started to be used widely.
B Moldrup


Comparative investigations on the influence of wood seasoning, wood properties and temperature on the toxic values of wood preservatives against Hylotrupes egg larvae
1970 - IRG/WP 28
Comparative tests carried out at three institutes indicated the influence of kiln temperature, position of wood specimens in the cross sectional area and test temperature on the toxic values determined in accordance with DIN 52165 with egg larvae of the house longhorn beetle (Hylotrupes bajulus L.). The preservatives applied were boric acid in distilled water and g-benzene-hexachloride dissolved in chloroform; the timber species used was pine sapwood, (Pinus sylvestris L.). The method of seasoning had no influence on the toxic values of boric acid. With the g-BHC, however, the toxic values gradually increased with rising kiln temperatures (20°C, 70°C, 105°C). With boric acid the position of the sapwood samples in the log had no influence on the toxic efficacy; with g-BHC the efficacy was slightly greater in the outer sapwood, compared with the inner sapwood. The test temperatures (20°C, 24°C, 28°C) yielded different toxicity results for boric acid. At 24°C and 28°C the threshold values were somewhat below those of 20°C; they agreed with the values obtained at 20°C after a longer test period. With g-BHC different temperatures did not affect the results. An explanation is suggested for the causes of the influence exerted by the kiln temperature and wood properties on the toxic values of g-BHC. There was good agreement between the toxic values obtained in the different institutes.
G Becker, T Hof, O Wälchli


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