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Status of the research and development of a new preservative system (EFPL) for pressure treatment of spruce in Canada
1975 - IRG/WP 348
Our work has been to develop a system which would have the stability of the ACA system and the formulation flexibility of the CCA system enabling properties such as fixation of arsenic, water repellency, appearance and cost to be controlled. Our permeability studies of spruce using a method previously developed indicated that an ammoniacal solution of copper arsenate is an excellent candidate for the treatment of spruce. Studies of the permeability of spruce sapwood microsections to CCA preservative and to an ammoniacal solution of copper arsenate proved that the ammoniacal system penetrates 1.7 to 1.8 times faster than the CCA system, in the radial direction. The permeability in the tangential direction was on the average 3.8 times better. These results were confirmed by pressure treatments of spruce lumber and spruce roundwood with both preservatives.
J Rak, M R Clarke

Marine testing of selected waterborne preservatives
1987 - IRG/WP 4137
In 1978 a marine test was established at West Vancouver, B C. to determine the performance of selected waterborne preservatives. The preservatives in test were chromated-copper-arsenate (CCA-C), ammoniacal copper arsenate (ACA), a modified formulation of ACA which contained a higher copper content (modified ACA), ammoniacal copper zinc arsenate (ACZA) and ammoniacal zinc arsenate (AZA). The wood species used for the test was red pine. After eight years in test the CCA is providing excellent performance at all retentions, while the modified ACA is showing significant deterioration only at the lowest level. The ACA is performing quite well although it shows signs of surface deterioration at all retention levels. The performance of the ACZA is rated as unsatisfactory at retentions below 32 kg/m³ while AZA was considered to be unsuitable for use in the marine environment.
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

Elimination of alternative explanations for the effect of iron on treated wood
1993 - IRG/WP 93-30006
Amounts of iron which had previously been found in stakes removed from ground contact reduced decay of untreated wood by four brown-rot fungi. This suggested that the effect of iron may be on the preservative. Analysis of the leachates from CCA- and ACA-treated wood blocks first exposed to rusting iron, then to a brown-rot fungus, showed that the increased decay found in the laboratory for wood exposed to iron was not due to enhanced leaching of the preservative.
P I Morris, J K Ingram, D L Gent

Water-borne preservative marine trials in Western Canada
1981 - IRG/WP 470
Red pine boards treated with chromated copper arsenate, ammoniacal copper arsenate, copper zinc arsenic additive, a modified ammoniacal copper arsenate, and zinc arsenic additive, have been installed in a marine field test at West Vancouver, British Columbia. After two and a quarter years exposure, all the test samples are in excellent condition with the exception of those treated with the zinc arsenic additive. All the zinc arsenic additive treated boards at the lowest preservative retention and two thirds of those at the second lowest retention in test have failed. A performance index calculated for the zinc arsenic additive indicates an added service life of 3% at the standard retention level.
J N R Ruddick

Disposal of treated wood - Canada
1990 - IRG/WP 3563
It is estimated that treated wood removed from service each year in Canada contains about 16,000 tonnes of creosote, 1000 tonnes of pentachlorophenol and 245 tonnes of CCA or ACA. The amount of CCA treated wood for disposal is expected to increase more than ten-fold by the year 2020. At present, most treated wood is disposed of in landfills, burned (creosote only) or recycled as other products. Other approaches to reduction, reuse, recycling and disposal are discussed.
P A Cooper

Use of the Pilodyn to assess deterioration of treated aspen waferboard after 30 months of outdoor exposure
1986 - IRG/WP 2254
Samples of preservative treated aspen waferboard exposed outdoors for 30 mo. were compared using pin penetrations of the 6 Joule Pilodyn. These results correlated well with rankings of treatment performance based on more laborious standard mechanical tests, and demonstrate the potential for use of the Pilodyn as a tool to evaluate wood composites in test exposures with minimal destruction.
E L Schmidt, M G Dietz

Available iron promotes brown rot of treated wood
1992 - IRG/WP 92-1526
Exposure of treated wood blocks to rusting iron increased the toxic threshold of chromated copper arsenate and ammoniacal copper arsenate to a brown-rot fungus Leucogyrophana sp. This supports the hypothesis that the movement of iron ions into wood contributes to the unexpectedly high decay rate of treated wood at the stake test site at Westham Island BC. To what extent this phenomenon may occur elsewhere has yet to be determined.
P I Morris

Corrosion of zinc-coated nails used with preservative-treated western red cedar shakes in service
1982 - IRG/WP 3197
The corrosion of metal fasteners used with certain wood species and with preservative-treated woods can be a serious problem. The chemical reactivity of western red cedar (Thuja plicata Donn) extractives to iron and copper is well documented and wood preservative treatments containing copper, chromium, and/or ammonium hydroxide can be expected to similarly attack some metals. This problem is compounded when red cedar is treated, and, such treatments with CCA and ACA have become customary in current efforts to extend the service life of shingles and shakes. Present recommendations for shake and shingle roof applications specify the use of hot-dipped zinc (iron) or aluminium nails. However, the use of nails made of stainless steel or other alloys of greater cost is advised with preservative-treated wood products.
R S Smith, E L Johnson, A J Cserjesi

Marine trials with ammoniacal wood preservatives
1980 - IRG/WP 423
Ammoniacal wood preservatives have been known for many years and are considered among the best water-borne systems for protecting wood in ground contact. In recent years attention has been increasingly focussed on these preservatives because of their ability to penetrate difficult-to-treat species better than most other fixed water-borne preservatives. This is particularly important for example, in eastern Canada, where there is an abundance of spruce and a relative shortage of easily treated woods such as pine. Besides being able to readily penetrate wood, the preservative must also be well fixed in the wood. We have concentrated in recent years on improving the already good fixation of ammoniacal copper arsenate and have paid particular attention to increasing the ratio of copper ions to arsenic ions, adding extra anions, and also substituting all or part of the copper by zinc. The preservatives thus formulated are termed copper arsenic additive (CAA), copper zinc arsenic additive (CZAA) and zinc arsenic additive (ZAA). Many of the properties of these preservatives have been reported elsewhere (Hulme, 1979). However, no reports have yet been prepared on their ability to protect wood in sea water. This first progress report indicates how well these preservatives protect wood against marine borer attack in Canadian coastal waters for at least 8 months.
M A Hulme, D P Ostaff

Application of a novel strength evaluation technique during screening of wood preservatives
1986 - IRG/WP 2262
The effectiveness of CCA and ACA in treated aspen mini stakes tested using a novel bag procedure, with unsterile soil fortified with Chaetomium globosum and Ceratocystis albida, is reported. Good agreement between toxic limits determined using the standard weight loss procedure, and those determined by the strength technique were found, with some indication that the strength loss method is more sensitive. The investigation also showed that the toxic limits for CCA (4.0-8.0 kg/m³) were twice those of ACA (2.0-4.0 kg/m³). In addition, based upon the strength loss, a CCA retention greater than 8.1 kg/m³ was required to prevent decay by Ceratocystis albida in this laboratory screening method.
J N R Ruddick

IUFRO rating system compares favourably to weight loss for soil-bed testing
1990 - IRG/WP 2343
The soil-bed/small stake test is commonly used for rapidly evaluating the performance of new, more environmentally acceptable, preservatives. In a 1.5 year experiment with three copper-based waterborne preservatives, visual evaluation and probing using the IUFRO performance rating scale (0-4) gave very similar toxic thresholds to those derived from measurement of weight loss at the end of the experiment. Visual evaluation therefore appears to be a reliable indicator for comparing the performance of these copper-based waterborne preservatives. However, caution should be exercised in interpreting performance rating data as the stakes approach failure.
P I Morris

Treatment of refractory timbers
1993 - IRG/WP 93-40001
Worldover crisis of wood is being felt due to the global environmental problems. Wood preservation technology plays a good role in curtailing the demands of wood for replacement by prolonging the service life of the timber and thus indirectly helps in saving the environment. Some species of timbers which could not be treated to the desired level by virtue of their refractory nature by any of the conventional preservatives CCA, CCB, ACC etc. even by pressure method fail to give longer service life. An attempt was made in Forest Research Institute (India) to treat such species with ammoniacal copper arsenite solution by simple soak treatment. This ensures good penetration (5-8 mm) and adequate absorption (10 kg/m³) in the treatment heartwood zones, of Eucalyptus and Prosopis sp. These two species have been planted in large quantities but have not found suitable use due to their nondurable nature and refractoriness to treatment. This development will help in utilisation of this resource for better purposed ensuring good return to the formers.
I Dev, S Kumar

Waterborne preservative treatability of tamarack (Larix laricina (Du Roi) K.Koch)
1998 - IRG/WP 98-40112
Eastern larch or tamarack (Larix laricina (Du Roi) K.Koch) lumber from New Brunswick, Canada was evaluated for preservative treatability with chromated copper arsenate (CCA-C) and ammoniacal copper arsenate (ACA). The fixation and leaching characteristics of CCA-C treated tamarack sapwood and heartwood were also evaluated. CCA-C penetration into both sapwood and heartwood was poor. ACA fully penetrated the sapwood but penetrated the heartwood only marginally better than the CCA-C. The rate of CCA-C fixation, as defined by the rate of reduction of hexavalent chromium, varied greatly between sapwood and heartwood and between different heartwood samples. Heartwood fixed much faster than sapwood, averaging 2-3 days at 21°C and 5-6 hours at 50°C compared with 15-20 days and 30-35 hours respectively, for sapwood. The fixation rate was directly related to the hot water soluble extractive content of the wood. The quality of fixation, as defined by resistance to leaching of the CCA-C components, was much lower for the faster reacting heartwood. The combination of poor penetration and low CCA-C stability in tamarack heartwood suggests that this preservative is not appropriate for this species.
A Taylor, Y T Ung, P A Cooper

Kerfing reduces checking in ACA-treated western white spruce poles
1988 - IRG/WP 3477
Western white spruce poles, pressure treated with pentachlorophenol and ammoniacal copper arsenate (ACA) were installed in the Westham Island test site. The pentachlorophenol treated poles were unkerfed, while both unkerfed and kerfed ACA poles were placed in test. The checking and kerf width and depth were recorded at the time of installation. After ten years of weathering the checking characteristics of the poles was evaluated. The check depth and width in the kerfed poles was significantly less than that in the unkerfed material. The average depth of the deepest check in the kerfed poles was ca. 43 mm while that in the unkerfed ACA poles was 92 mm. Kerfing also reduced the degree of secondary checking in the poles.
J N R Ruddick

Diffusion and interaction of components of water-borne preservatives in the wood cell wall
1988 - IRG/WP 3474
This study investigates the rates of diffusion and ultimate distributions of copper and arsenate components of wood preservatives in wood cell walls following vacuum treatment. Adsorption studies of copper on red pine (Pinus resinosa) and trembling aspen (Populus tremuloides) wood confirm the importance of cation exchange reactions on the ultimate distribution of copper in the wood substance and its strong dependence on pH of the treating solution. Formulations containing both copper and zinc preferentially adsorb or exchange copper relative to zinc. Under high pH conditions, the arsenate anion is significantly adsorbed into the cell wall. The combined adsorption and fixation of low pH CCA solutions is much slower than adsorption of high pH ACA and CZA formulations, but the reaction with wood is more complete. Diffusion coefficients were estimated for the movement of copper and arsenate components of ACA in cell wall material of both aspen and pine sapwood using a simple membrane model for non-steady state diffusion. The longer diffusion paths inherent in the diffuse porous hardwood (aspen) resulted in much slower equalization of the solute in the cell wall matrix than in red pine. However, in both species, equalization was achieved in a relative short time compared to accepted fixation times for conventional waterborne wood preservatives.
P A Cooper

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

The effect of kerfing on check formation in treated white spruce (Picea glauca) poles
1981 - IRG/WP 3167
62 white spruce poles, 6 m in length, were cut from full size utility poles commercially pressure treated with preservative. 21 of the poles were treated with pentachlorophenol, while of the remainder, all of which were treated with ammoniacal copper arsenate, 22 were kerfed and 19 were unkerfed. The poles were installed in the Westham Island field test site, near Vancouver, and inspected annually. After three years of exposure, deep checks have formed in the unkerfed ACA and PCP treated poles. The average depth of the "worst" check (i.e. that which penetrated the poles to the greatest depth) in the unkerfed ACA treated poles is 2.2 times that of the poles which were kerfed. No significant difference was detected in the depth of the worst check in the unkerfed poles treated with either ammoniacal copper arsenate or pentachlorophenol.
J N R Ruddick

A determination of the toxic level of ACQ2100 wood preservative for the powder post borer Lyctus brunneus (Stephens)
1994 - IRG/WP 94-20029
The sapwood of two Lyctus susceptible Australian hardwoods, messmate (Eucalyptus obliqua L'Herit.) and black bean (Castanospermum australe A. Cunn. et Fraser ex Hook) were pressure impregnated with ACQ2100, a wood preservative, to produce replicates of a range of retentions. Preservative retentions were determined by solution weight uptake at treatment and chemical analyses of selected samples was attempted. After post treatment seasoning, timber specimens were exposed to fresh adult Lyctus (Stephens) beetles and allowed to stand in an environment controlled insectary. After 1.5 times the life cycle time for the insects in control specimens, the trial was evaluated for Lyctus activity. A table of preservative retentions and insect activity is provided. A toxic level of ACQ2100 for Lyctus is proposed.
A R Moffat