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Effect of incising depth and density on treatment of Douglas fir, hem fir and spruce-pine-fir lumber with CCA, ACZA or ACQ
1997 - IRG/WP 97-40093
Incising markedly improves both the depth and uniformity of preservative treatment of refractory wood species, but there are few studies directly comparing the effects of incising depth and density on penetration and retention of commonly used waterborne preservatives in wood species from the western United States. The effects of two incision densities (7300 and 8900 incisions/square meter) at two depths (5 and 7 mm) were investigated using two strength classes of Douglas fir, hem fir and spruce-pine-fir lumber. In general, grade or strength class had no significant effect on treatability. Treatability markedly improved with increasing incision depth, while increased incision density produced less tangible results. Ammonia-based treatments were associated with deeper penetration reflecting the ability of the heat and/or ammonia to improve preservative penetration. Further studies are underway to evaluate the effects of incising and subsequent preservative treatment on strength properties.
M Anderson, J J Morrell, J E Winandy


A Soil Bed Test of the Effect of CCA Penetration on the Performance of Hem-fir Plywood
2004 - IRG/WP 04-30332
An accelerated decay test was set up to compare the performance of CCA-treated Western hemlock/amabilis fir plywood treated to meet the preserved wood foundation (PWF) retention standard with various patterns of preservative penetration. Short lengths of treated plywood and comparable untreated material were installed in a soil bed. After eleven years of exposure, the CCA treatments were all sound regardless of penetration, while the untreated material had failed due to decay within three years.
P I Morris, J K Ingram


Long-term protection of stored lumber against mould, stain, and specifically decay: A comparative field test of fungicidal formulations
1984 - IRG/WP 3281
The problem of decay in packaged, unseasoned lumber stored for many months has become of major importance in recent years. Large financial claims have resulted from decay in Canadian lumber stored at length in seaports and storage yards of distributors. For decades acceptable protection from moulds and sapstain was readily achieved with chlorinated phenols applied at appropriate treating levels. However, in recent years, the use of chlorinated phenols in sawmills has become controversial, out of concern for its persistance in the environment and because of its broad spectrum of toxicity to practically all organisms. Although it was realized that this toxicity to humans had been over-emphasized, the discovery of traces of chlorinated dibenzodioxins as a minor impurity of some chlorinated phenols has generated further pressure to abandon the use of the latter. Forintek Canada Corp. has done extensive laboratory and field testing of fungicides for the lumber industry. Most of the field experiments were four-month studies (1) although one dealt with a two year evaluation of preservative retention and protection (2). In June 1981, under contract to Agriculture Canada, we began a field test of five new fungicidal formulations, comparing them with sodium tetra- and pentachlorpheates (NaTCP).
A J Cserjesi, A Byrne, E L Johnson


Performance of non-incised CCA-treated hem-fir decking
1993 - IRG/WP 93-40004
The question of what preservative penetration will provide an acceptable service life for treated wood in residential above-ground applications is topical in North American standards committees. Non-incised CCA-treated nominal 2 x 4 inch² hem-fir decking with penetrations close to the proposed CSA O80 2 decking standard of 80% over 5 mm, has remained without decay after 10 years exposure in south western British Columbia. Material with minimal preservative penetration showed early signs of decay. In contrast untreated unstained material had reached a rating of 1.1 on a 0 to 4 scale (0 = sound) with 12% of boards needing replacement. These results support consideration of a reduced penetration requirement in the standards for CCA treated decking.
P I Morris, J N R Ruddick


Comparative studies on the species effects of wood preservatives
1989 - IRG/WP 3521
For the examination of the resistance against fungal attack, wood blocks of 3 softwood species were treated with CCA (type 3), CFK, AAC and IF-1000 independently. The wood blocks were exposed to the fungal decay with Tyromyces palustris. The degradation of the wood blocks treated with these preservatives was quite widely different among wood species examined in this study. Hem-fir treated with CCA and radiata pine treated with CFK showed less durability than the other species and other preservatives. In the case of Cryptomeria japonica, all preservatives tested gave good results. The micromorphological distribution of preservatives in cell walls was investigated with the wavelength dispersive X-ray spectrometry. The X-ray photoelectron spectroscopy was applyed for the investigation on the possibility of conversion reactions with preservatives in impregnated wood. The interaction of extractives with preservatives was examined using a conventional bioassay method for evaluations of the efficacy of wood preservatives against fungi. The concentration of Cr in the CCA treated wood was 1.5-1.6 times higher in the ray parenchyma cell walls than in tracheid walls in every wood species examined. The oxidation of wood occur during the treatments with CCA and CFK, however, there were not conspicious differences in the degree of oxidation among wood species. Although the hot water extractives themselves accelerated the mycelial growth, only the extractives of hem-fir reduced the efficacy of CCA.
K Yamamoto, S Matsuoka


Movement of borates in a range of timber species at various moisture contents
1998 - IRG/WP 98-30181
Borate-based wood preservatives are used in industrial pre-treatment as well as remedial treatment of timbers in situ. In both of these areas, understanding the mobile nature of these compounds is important in optimizing the main benefits of borates. Considerable work has been conducted on movement of borates in dip-diffusion treatment of freshly felled wood, as well as focusing on subsequent diffusion following remedial application to dry timber. This paper sets out to review the existing body of data of borate movement in wood, in the context of more recent research findings. Data are presented which show that the movement of borates, up to 6 months after dip treatment of a range of commercially important softwoods, is highly dependent on wood moisture content. Moisture content is of such over-riding importance that the identity of a particular timber species has an insignificant effect on borate movement, provided a minimum moisture content is attained. This observation is despite the fact that species as diverse as Douglas fir, Hem-fir, Southern Yellow Pine, Scots Pine and Norway Spruce were used in this study. It has been suggested that there must be free water in the wood cell wall voids for significant diffusion of borate to occur. However, the precise influence of decreasing moisture content on the rate of borate diffusion is unclear. The data presented in this paper contribute to a more comprehensive understanding of borate movement at moisture contents representative of those seen in timber post-treatment and in-service. In addition, the importance of backing up results from colorimetric spot tests with detailed measurement by analysis is illustrated.
M W Schoeman, J D Lloyd, M J Manning


Fluoride movement through Douglas-fir and hem-fir lumber following dipping in potassium/ammonium bifluoride
1995 - IRG/WP 95-40040
The ability of ammonium and potassium fluoride to diffuse through Douglas-fir and hem-fir lumber was evaluated over a 90 day period. Boards were dipped in a solution containing 10% (by weight) of ammonium and potassium bifluoride, then stored under cover for 90 days. Samples removed 30, 60 and 90 days after treatment indicated that the fluoride was unable to completely penetrate the wood. Penetration was markedly better in hem-fir, reflecting the greater permeability of this species. Increasing the dipping time had only a marginal effect on chemical uptake. Longer diffusion periods also had little effect on fluoride movement. Chemical assays of increment cores removed from the boards indicated that most of the chemical was detected in the outer 5 mm, although fluoride was present 5 to 15 mm from the surface. The results suggest that fluoride treatment can not completely diffuse through freshly sawn lumber at levels which would confer protection against many wood inhabiting organisms.
J J Morrell, C S Love


A study of fungal biodeterioration in unseasoned, packaged hem-fir lumber
1978 - IRG/WP 2116
This study was undertaken to determine the extent of biodeterioration that could occur within British Columbia (BC) prior to the export of packaged Canadian Lumber Standard Hem-Fir (Tsuga heterophylla, Abies amabilis and small amounts of Abies grandis). By examining the anti-stain treatments received by the lumber and identifying and characterizing the organisms responsible for the biodeterioration, recommendations can be made to the industry for improved quality control. The majority of unseasoned, packaged Hem-Fir lumber awaiting export from BC is less than 5 months old. During this period of transit and storage, fungal biodeterioration is observed to be slight, in spite of low anti-stain chemical retentions indicated by analysis. However, after eight months in transit, packages show a significantly greater percentage of heavily stained pieces and increased spread of infection by wood-destroying fungi. Of the fungi responsible for the observed biodeterioration, Graphium was found to be the most common staining organism and Fomes pinicola the most abundant wood-destroying fungus. Decay studies of hemlock sapwood showed that Fomes pinicola poses a serious threat to packaged Hem-Fir lumber, with the potential ability to cause rapid and widespread decay. Based on these findings, and the previous work of Roff, Cserjesi and Swann (1974), recommendations are being made to BC lumber manufacturers for improving their anti-stain treating methods. Increased chemical retention on the lumber can be obtained by dipping individual pieces of lumber or otherwise thoroughly drenching with anti-stain solution instead of using the spray systems currently in use. In addition, increasing the concentration of the anti-sapstain solution will result in a surface retention of chemical capable of preventing attack by moulds and staining and wood-destroying fungi. Implementation of these recommendations will result in improved quality of Hem-Fir lumber for the export market and in the long term contribute to the conservation of Canada's lumber resources
P W Perrin, A J Cserjesi


Long term marine performance of ACZA treated Hem fir in Krishnapatnam harbour, east coast of India
2006 - IRG/WP 06-30409
The performance of Hem fir (Tsuga heterophylla) and Southern pine (Pinus sp.) treated with ammoniacal copper zinc arsenate (ACZA) and copper dimethyldithio carbamate (CDDC) at two retention levels of each preservative was assessed in tropical marine waters at Krishnapatnam harbour on the east coast of India. Panels treated with ACZA of lower loadings (23.1 Kg/m3) had failed in 38 months while the performance of higher loadings (38.1 Kg/m3) was very effective and lost in 54 months. Panels treated with CDDC of lower loadings (4.31 Kg/m3) was severely attacked by borers and lost in 22 months and higher loadings (10.86 Kg/m3) damaged in 38 months. The results indicate that, ACZA at higher lodgings is very effective in tropical waters and durability enhanced over 13 times compared with untreated controls. Teredinids were important on control panels, while ACZA treatment was damaged mainly by pholads. Nine species of borers were identified on panel including 2 species of pholads and 7 teredinids. The fouling biomass was slightly higher on CDDC treatments than ACZA and barnacles, bryozoans, oysters and serpulids were dominant groups on test panels.
B Tarakanadha, K S Rao, J J Morrell


Effect of fungal attack on maximum load capacity of simulated wall assemblies
2007 - IRG/WP 07-20363
The effects of moisture intrusion and fungal attack on the maximum load capacity of nailed assemblies was investigated using one white and one brown rot fungus against 4 material combinations over a 20 week period. Wetting significantly reduced the maximum load capacity of all four material combinations, while wetting and autoclaving only affected the OSB sheathing/spruce stud. The white rot fungus (Trametes versicolor) had no significant effect on the maximum load, while the brown rot fungus (Gloeophyllum trabeum) produced significant load reductions on shear connector assemblies with OSB sheathing. Results indicate that moisture remains the dominant factor in the performance when water intrudes into wall assemblies.
N Melencion, J J Morrell


Field performance of wood-based decking materials in the Western United States
2014 - IRG/WP 14-30645
While wood has long been used for the construction of decks and other outdoor features, a variety of wood-plastic composite (WPC) decking products have emerged over the past decade with claims of exceptional durability and low maintenance. There are relatively few long term comparative tests on these products. The performance of selected WPC decking products was compared with naturally durable western redcedar or pressure treated lumber on the basis of appearance, loss of colour and water repellency. All materials experienced losses in colour, water repellency and appearance over the 10 year exposure.
S Lipeh, C S Love, J J Morrell


Application of radio frequency heating to accelerate fixation of CCA in treated round-wood
1999 - IRG/WP 99-40133
The potential of radio frequency heating to accelerate the fixation of chromated copper arsenate (CCA) in treated round-wood was assessed. Pre-dried Douglas-fir and western red cedar round-wood sections were pressure treated with CCA in a pilot plant retort, after which they were placed individually in a pilot radio frequency (RF) chamber. Based upon the color reaction of chromotropic acid with hexavalent chromium and the quantitative assessment using diphenyl carbazide, fixation was achieved in less than 6 hours. During heating, the temperature at various locations inside the pole sections was monitored by fiber-optic thermocouples. The moisture profiles before, and after fixation, were also recorded. Further studies will examine other benefit of RF heating, including a) sterilization, and b) rapid drying of round-wood with minimum check formation.
Fang Fang, J N R Ruddick


Treatability of plywood containing intermountain Douglas fir veneers
1982 - IRG/WP 3203
Eighteen sheets of plywood were obtained which contained intermountain Douglas-fir veneers from two regions of British Columbia. Following pressure treatment with chromated copper arsenate (CCA type C) and ammoniacal copper arsenate (ACA) the preservative penetration and retention in individual veneers was assessed. It was concluded from the study that the intermountain Douglas-fir veneer could not be adequately penetrated by either CCA or ACA, although the degree of penetration achieved with ACA was better than that recorded for CCA. The preservative retentions measured were generally in excess of that required for plywood to be used in the preserved wood foundation system.
J N R Ruddick, A Walsh


Gloeophyllum trabeum and Gloeophyllum abietinum, the most frequent brown rot fungi in fir wood joinery
1999 - IRG/WP 99-10319
In Croatia the primary raw material for joinery production is silver fir wood (Abies alba Mill). L-joints made of home-grown fir sapwood and prepared according to EN 330: 1993 were used to establish the infection and colonisation of micro-organisms, particularly wood decay fungi, to compare the performance of untreated and 1% TnBTO treated L-joints. The L-joints were coated with two types of coat, and 36 months exposed in Zagreb. The first type of coat was alkyd paint and the second was a stain, in three different colours: white, brown, and black. The influence of the preservative, and the type of coat were most important factors which affected the rate of colonisation. The influence of coat colours was significant at the the beginning of exposure. The fastest and the strongest colonisation occurred in untreated L-joints coated with alkyd paint and the lowest colonisation occurred in treated L-joints coated with stain. It was due to the well known vaporous diffusivity of the stains and the low natural permeability of fir sapwood. The most frequently isolated fungi were Gloeophyllum trabeum (Pers.: Fr.) Murr. and Gloeophyllum abietinum (Bull.: Fr.) Karst.
R Despot, M Glavas


Effect of a penta emulsion on the service life of Douglas fir, heartwood posts
1978 - IRG/WP 3112
C S Walters


Movement of boron from fused boron rods implanted in Southern pine, Douglas fir, red oak, and white oak timbers
1995 - IRG/WP 95-30061
This paper reports the distribution of boron from fused boron rods installed into six-inch (15.2 cm) square timbers of Douglas-fir, Southern Pine, red oak and white oak exposed aboveground. The composition and size of rods was: sodium borate and sodium borate-copper oxide (8.5 x 100 mm²); sodium borate-copper, sodium borate and boric oxide-copper oxide (12 x 76 mm²). The boric acid equivalent was roughly monitored by the curcumin/salicylic acid color test and the presence of copper was detected by the chrome azurol-S reagent. One year after installation of rods, movement of boron was determined by application of curcumin dye to increment cores removed at various distances from the site of boron rod installation. A portion of a sodium borate treated Southern Pine timber was also analyzed by spraying curcumin dye on sawed longitudinal and transverse sections. At 2 years, one foot sections were removed from all timber species, sawed as above, and boron and copper detection reagent sprayed on the sawed surfaces. Movement of copper from rods in all timbers was virtually nil. Both transverse and longitudinal movement of boron from rods was greatest in Southern pine which also had the highest moisture content. Movement of boron was next best in red oak. There was little movement of boron away from the rods in white oak and Douglas-fir.
T L Highley, L Ferge


Long-term effectiveness of fumigants in controlling decay in Douglas fir waterfront timbers
1986 - IRG/WP 3364
The persistence, movement, and effectiveness of chloropicrin and Vapam (sodium N-methyl dithiocarbamate) in large, horizontal Douglas fir timbers were evaluated 7 years after fumigation. Chloropicrin prevented reestablishment of decay fungi; reinvasion occurred in some Vapam-treated timbers. Residual fungistatic effect was detected up to 1.2 m from the fumigation site in chloropicrintreated timbers but not in Vapam-treated timbers.
T L Highley


A behaviour of CCA penetration of fir (Abies bornmulleriana Mattf.) at different ramp times and constant vacuum/pressure applications
2006 - IRG/WP 06-40346
A behaviour of CCA penetration of Bornmulleriana fir (Abies bornmulleriana Mattf.) at different ramp times and constant vacuum/pressure applications was illustrated for the main flow directions by the experimental pictures.
I Usta, R Despot, M Hasan


Above ground performance of CCA-treated fingerjointed lumbe
1993 - IRG/WP 93-40003
Studs made from short lengths by finger jointing are becoming more commonly used in North America. Recently Forintek has received enquiries about the performance of such material in a treated form. Treated and untreated nominal 2x4 inch² spruce-pine-fir (SPF) studs exposed above ground for 12 years in southwestern British Columbia were evaluated for evidence of decay. Despite shallow preservative penetration, which did not meet North American standards, the CCA-treated material showed no signs of decay. In contrast two of the 30 untreated samples had failed and the mean rating was 1.3 on a 0 to 4 scale. These results are encouraging for the use of CCA treated SPF as finger jointed or conventional lumber in above ground exposure.
P I Morris, G E Troughton


Sequential exposure of borate treated Douglas-fir to multiple Formosan subterranean termite colonies in a 40-week field test
1993 - IRG/WP 93-10006
Douglas-fir boards (ca. 74.5 g) pressure-treated with disodium octaborate tetrahydrate (DOT) retentions of 0 (controls), 0.88, 1.23, 1.60, or 2.10% (weight/weight) DOT were sequentially exposed to four active field colonies of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in an above-ground field test. Samples were placed in contact with each colony for 10 weeks, with oven-dry weight losses determined between exposures, for a total termi exposure period of 40 weeks. Feeding activity differed among termite colonies, with the control wood samples having mean weight losses of 1.3-15.1% of their initial weight during each individual 10-week termite exposure. The two lower borate retentions (0.88 and 1.23% DOT) were virtually equal efficacy, with mean wood weight losses during each individual 10-week exposure ranging from 1.2-4.6%. Feeding was negligible at the two higher borate retentions, with mean wood weight losses from termite feeding during each 10-week period ranging from 0.7-1.3% with 1.60% DOT, and 0.3-0.9% with 2.10% DOT. Total cumulative wood weight losses over the 40 week exposure were: 10.2% (0.88% DOT), 8.7% (1.23% DOT), 3.6% (1.60% DOT), and 2.4% (2.10% DOT).
J K Grace, R T Yamamoto


Effect of fatty acid removal on treatability of Douglas-fir
1993 - IRG/WP 93-40008
Treatment of Douglas-fir with chromated-copper-arsenate (CCA) poses a major challenge. Several hypotheses based on the anatomical aspects as well as chemical reactivity of the preservative formulations with cell wall constituents and deposits have been proposed. Techniques to prevent pit aspiration or slow fixation reactions have, however, not significantly improved treatment. The presence of high molecular weight fatty acids have been reported to be responsible for higher hydrophobicity in some wood species. These acids can react with Cu+2/Cr+3 ions to form insoluble metallic soaps, thereby immobilizing Cu/Cr and increasing wood hydrophobicity by a mechanism similar to that employed in paper sizing. The effect of fatty acids on treatability was explored by removing these components via several extraction methods. In general, extracted wood had higher gross solution absorptions and chemical retentions, but preservative penetration was largely unaffected. The results suggest that removal or disruption of fatty acids can improve treatability of Douglas-fir heartwood.
S Kumar, J J Morrell


Studies on the biological improvement of permeability in New Zealand grown Douglas fir
1983 - IRG/WP 3231
This report outlines progress towards optimizing conditions for water storage of New Zealand grown Douglas fir with the aim of improving permeability to water-borne preservatives, in particular CCA. Small scale laboratory tests are in progress but the need to scale up to potential commercial applications is being considered. Mixed populations of bacteria isolated from 10 week water sprinkled Douglas fir are being used to inoculate green, sterile timber. Environmental parameters such as pH, temperature and nutrient status are controlled to evaluate optimum conditions of growth, enzyme production and pitmembrane degradation leading to permeability improvement.
K J Archer


Evaluation of Barrier Wrap Systems after 71 Months of Exposure
2013 - IRG/WP 13-40631
A 71 month study of the performance of booted samples in ground contact was conducted in AWPA hazard zone 4. Data indicated that excellent performance of wrapped systems, even over untreated wood, could be obtained. Instances of decay colonization or termite attack could all be attributed to some breaking of the integrity of the barrier system. Good performance for treatment below ground contact threshold was demonstrated.
H M Barnes, M G Sanders, G B Lindsey, C McIntyre


Treatment of Douglas fir heartwood with disodium octaborate tetrahydrate (Tim-BorÒ ) to prevent attack by the Formosan subterranean termite
1991 - IRG/WP 1487
Toxicity of disodium octaborate tetrahydrate (Tim-BorÒ) to Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), and termite feeding on treated Douglas-fir heartwood were evaluated in laboratory and field tests. Feeding on filter papers impregnated with Tim-BorÒ solutions reduced but did not eliminate termite gut protozoan populations. In a forced-feeding laboratory assay, Douglas-fir heartwood treated to Tim-BorÒ retentions ³0.35% BAE drastically reduced termite feeding and resulted in 100% termite mortality within three weeks. Gradual and significant mortality (49%) after four weeks of feeding at 0.16% BAE suggests that this or lesser concentrations may be useful in baits for remedial termite control. After 162 days of field exposure to an active Coptotermes formosanus colony in an accelerated field test, moderate feeding was noted at 0.65% BAE (13.6% weight loss) and 0.73% BAE (16.9% wt. loss), and only slight damage (2.5% wt. loss) at the highest retention field tested of 1.02% BAE. These results indicate that Tim-BorÒ provides protection from Formosan termite attack, but that some cosmetic damage occurs even at high retentions. This cosmetic damage is unlikely to create a structural hazard, but additional field evaluations are needed to determine the treatment requirements for timbers visible to the consumer.
M Tamashiro, R T Yamamoto, J K Grace


Development of decay in untreated, second-growth Douglas-Fir using two exposure techniques in North Queensland
1997 - IRG/WP 97-20110
The results of two exposure techniques for evaluating the development of wood decay in untreated, mill-run lumber from second-growth Douglas-fir containing both sapwood and heartwood are presented. Nominal 50 mm by 100 mm by 2.5 m (2 in. by 4 in. by 8 ft) lumber, No 2 and better, was obtained from a production run in a mill that was processing second growth, Coastal Douglas-fir in western Oregon, USA. Untreated wood members were kiln dried, then shipped to Queensland. At the Timber Research Laboratory, Indooroopilly, Queensland, two units for above-ground exposure were fabricated from each 2.5-m (8-ft) untreated member. A 600-mm (2-ft) length was cut from each end of each member. One 600-mm section was transversely bisected, forming two, 300-mm (12in.) units; the other 600-mm section was used in a separate study. The middle 1200-mm (4-ft) length was used as one exposure unit. These shorter members were then milled to form a joint with a 100-mm (4-in.) overlap. Two holes were drilled through the overlapping portions, and the two sections were bolted together. The identity of the 1200mm length and the end-matched lapped jointed section was maintained throughout the exposure. Both units were positioned on a horizontal support approximately 1 m above ground in an open field near Innisfail, Queensland. As units were installed in the field, all cut surfaces inside the joint and at the ends were brush coated with a commercially available (in Australia) copper naphthenate emulsion containing 1% copper. Decay was first detected after 2 years of exposure and it advanced rapidly during the third year. The pattern of results suggests that the weathering of the upper, exterior surface and the retention of a high moisture content by the 50-mm-thick wood, when wetted, is more important in predisposing wood to decay than is end-grain absorption of moisture. Decay ratings for the 1200-mm members were equivalent to those observed with the lapped joints. The two types of units are of equal utility in demonstrating the potential for decay in a wood material that has natural susceptibility to decay.
J Norton, S Kleinschmidt, R C De Groot, D Crawford


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