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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


Migration of Metals from Douglas-fir Lumber Treated with ACZA or Pentachlorophenol Using Best Management Practices: Preliminary Tests
2005 - IRG/WP 05-50224-4
The potential for migration of preservative components from ammoniacal copper zinc arsenate (ACZA) and pentachlorophenol treated Douglas-fir lumber in non-soil contact exposure was assessed in a simulated rainfall device. Metal levels from ACZA treated wood were elevated for the first 30 minutes of rainfall and then declined sharply. Repeated cycles of rainfall led to declines in initial metal losses suggesting that surface metals were gradually depleted from the wood. Penta losses were also initially high, but then declined at rates related to rainfall level. The results suggest that preservative losses from treated wood in above ground exposures can be predicted.
J J Morrell, Hua Chen, J Simonsen


The effect of selective additives and conditions on the decomposition of Basamid in Douglas fir heartwood
1992 - IRG/WP 92-3698
Basamid is a solid, powdered chemical used as an agricultural soil fumigant. Decomposition of Basamid isothiocyanate, hydrogen sulfide, methyl amine, and formaldehyde. Basamid has some potential as a wood fumigant, but it decomposes too slowly to be effective. Various additives and conditions were tested for their ability to enhance Basamid decomposition in Douglas-fir heartwood. Higher MC's and temperature, as well as copper sulfate and powdered pH 12 buffer increased decomposition rates with copper increasing the efficiency of breakdown to form MITC.
P G Forsyth, J J Morrell


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


Movement and persistence of Dazomet and pellected methylisothiocyanate in wrapped Douglas fir and southern pine timbers
1991 - IRG/WP 1496
The movement and persistence of Dazomet (tetrahydro-3,5-dimethyl-2 H-1,3,5 thiadiazine-6-thione) and pelleted methylisothiocyanate (MIT) was evaluated in wrapped Douglas-fir and Southern Pine timbers. MIT pellets did not impart a fungistatic effect to any of the timbers. Failure of MIT was probably due to loss of MIT from pellets prior to application. Fungistatic effect of Dazomet was consistently detected at 0.3m from the treatment center but effect beyond this distance was variable. Fungistatic effect was detected at 2 years after Dazomet treatment in Southern Pine but not at 3 years. Fungistatic effect was still present in Douglas-fir timbers at 3 years.
T L Highley


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


Comparative moisture uptake of Douglas fir and radiata pine structural lumber when exposed to rain wetting as an indicator of relative decay resistance
2004 - IRG/WP 04-20285
Trials were undertaken to determine the relative resistance of radiata pine and Douglas-fir to wetting when exposed to the weather. Douglas-fir samples were obtained from one Central North Island and three South Island sources and had a heartwood/sapwood mix typical for each resource. Radiata pine sapwood and heartwood samples were obtained from a Central North Island source. Material was exposed to the weather as horizontal studs in the first trial, and as horizontal and vertical studs in the second trial. The first trial ran over later winter from 29 July to 22 September 2003; the second, and more comprehensive investigation, from 22 October to 17 December 2003. In the first trial, after seven days exposure, radiata pine reached a moisture content which would sustain decay (~27% mc), and remained well above that moisture content for the remaining 48 days of the trial. However, the maximum moisture content attained by Douglas-fir throughout the trial was only 21.8 % mc. In the second trial, radiata pine sapwood rapidly attained a moisture content conducive to decay, and Douglas-fir did not. Because of the warmer and sunnier weather, fluctuations in moisture content were more pronounced than in the winter trial. Samples exposed horizontally attained higher moisture contents than those exposed vertically, irrespective of wood species or relative heartwood/sapwood content. It is concluded that Douglas-fir timber shows significant positive differences from radiata pine in terms of susceptibility to moisture uptake. This trial confirmed the ‘refractory’ reputation of Douglas-fir, and the ‘absorbent’ reputation of radiata pine. At a practical level, Douglas-fir heartwood and sapwood can be regarded as equally impermeable, and independent of where in New Zealand it was grown.
M E Hedley, G Durbin, L Wichmann-Hansen, L Knowles


Relationship between bond strength and surface characteristics of CCA-treated Douglas-fir
1993 - IRG/WP 93-30008
Chromated-copper-arsenate (CCA) treated Douglas-fir was laminated using a commercial phenol-resorcinol resin. CCA treatment enhanced the water repelleney of wood espeeially in the presence of extractives. However, the shear strength of CCA treated wood was 12% lower in dry condition and 38% lower in wet condition after six cycles of vacuum-pressure test than that of untreated wood. Slight removal of treated wood surface by planer or sander contributed for better adhesion, although it was not enough. The characteristics of treated wood surface was analyzed by X-ray photoelectron spectroscopy (XPS). CCA treatment increased C1 (C-H) and decreased C2 (C-OH), indicating migrated exctractives have enhanced the water repelleney of treated surface. The removal of hydrophobic surface of CCA-treated wood decreased C1 component of C1s spectra on the new surface.
K Yamamoto, J N R Ruddick


Diffusion of a copper naphthenate/boron paste through Douglas fir heartwood
1991 - IRG/WP 3671
Groundline wraps are an important portion of the remedial treatment strategies for protecting utility poles in North America from surface decay. The compositions of these wraps have recently shifted away from pentachlorophenol and creosote to formulations containing copper naphthenate and boron. These formulations have not yet been extensively tested, although the chemicals have been used for many years in other applications. Radial and longitudinal diffusion of the components of a copper naphthenate/boron paste was studied in Douglas-fir heartwood blocks at 30 and 60% moisture content. Longitudinal orientation and higher moisture levels resulted in greater diffusion of both components. Boron diffused faster than copper naphthenate over the 6 month test period, but the degree of copper movement was substantial. The results suggest that this copper/boron paste can readily diffuse through normally refractory heartwood. Field trials are underway to evaluate the biological efficacy of this formulation.
P G Forsyth, J J Morrell


Serviceability of copper naphthenate-treated poles
2000 - IRG/WP 00-30214
Copper naphthenate-treated poles in service were inspected for deterioration, penetration, retention, and serviceability. The study to date has included poles in all hazard zones in the United States. Poles installed by 12 different utilities and eight different treating companies are included in the survey. Both southern pine and Douglas-fir poles and distribution and transmission poles are included in the survey. Only two of the surveyed poles were considered failures, indicating that properly treated copper naphthenate poles are performing satisfactorily.
H M Barnes, M H Freeman, J A Brient, C N Kerr Jr


The influence of wood moisture content on the fungitoxicity of methylisothiocyanate in Douglas fir heartwood
1987 - IRG/WP 3430
The fumigant methylisothiocyanate (MIT) effectively controls decay fungi in large wood structures, but the influence of environmental factors on its performance are not well understood. Experiments found wood moisture content to greatly influence the fungitoxicity and sorption of MIT in Douglas fir heartwood. At constant, low MIT vapor concentrations (less than 1 µg/cc air), wood at 10% MC bound 5 times more MIT, but required 4 times the exposure period to control the decay fungus Poria carbonica, than similarly treated wood above the fiber saturation point. Sorption of MIT to wood was strongly influenced by wood moisture content, but was not substantially influenced by the amount of wood decay. Increasing wood moisture content from 10% to 30% during fumigation resulted in a rapid volatilization of previously bound MIT and a dramatic increase in fumigant fungitoxicity. The increased fungitoxicity of MIT in wet wood may help explain why Vapam (a 32% solution of sodium N-methyldithiocarbamate in water), which decomposes to produce MIT, has performed well as a wood fumigant.
A R Zahora, J J Morrell


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