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Laboratory Studies on Copper Availability in Wood Treated with Soluble Amine Copper and Micronized Copper Systems
2008 - IRG/WP 08-30489
A laboratory method has been employed to investigate the level of soluble copper in wood treated with various copper-based preservative systems, such as micronized copper (particulate copper) and amine copper solutions. This report describes the methodology and preliminary results on determination of the soluble copper in the treating solutions and the treated wood by these systems, as well as the potential impact on performance of such systems against wood decay fungi.
L Jin, P Walcheski, A Preston

A case study on quality control on telephone poles as a cost saving tool in Tanzania
1987 - IRG/WP 3418
A sample of 28 CCA treated Eucalyptus poles from a lot of 2,000 poles awaiting delivery to the field, was studied to reveal the quality of treatment. Results showed a product of very poor quality. Average figures for penetration and retention were 8.4 mm and 2.2 kg/m³; these results are 66% and 91% below the required standards, respectively. Consequences of such results are estimated to amount to losses of billion of shillings.
K K Murira

Treating Eucalyptus tereticornis wood with boron: Optimizing treatment conditions
2005 - IRG/WP 05-40309
Even though Eucalyptus tereticornis wood is suitable for small timber purposes, being non-durable, it needs to be treated with preservative chemicals. As it is a heavy, hard and difficult to treat species, the possibility of using diffusible boron compounds was investigated. The present study explored the effect of impregnation conditions such as treatment schedule, concentration of treatment solution and the moisture content of wood on the achievement of desired dry salt retention (DSR) of the preservative in the treated wood by conducting a commercial scale trial. The study revealed that wood density and moisture content adversely affected the boron impregnation. It was clear that even E. tereticornis wood in green condition could be effectively boron impregnated using appropriate treatment schedule. Only long duration treatment schedules were found to yield the desired DSR levels. A solution concentration of 8% boric acid equivalent (BAE) was found to be required. Application of an initial vacuum of 760 mm Hg (- 85 kPa) for 15 minutes followed by a pressure of 1300 kPa for a minimum period of 60 minutes and a final vacuum of 760 mm Hg(- 85 kPa) for 5 minutes was found to be an appropriate treatment schedule.
T K Dhamodaran, R Gnanaharan

CCA fixation experiments. Part 1
1989 - IRG/WP 3504
A method of squeezing solution from CCA treated wood that has not been dried at various times after treatment appears to be useful in following the fixation of CCA in wood. Experiments confirm that temperature governs the rate of fixation.
W S McNamara

Investigation of the fixation in wood of chromated zinc chloride and copperised chromated zinc chloride preservatives
1976 - IRG/WP 372
A biological method of evaluating the extent to which CZC and CCZC preparations are retained in wood in terms of the potential protection which they afford against destruction by Merulius lacrymans (dry rot) is given. CCZC is recommended for protection of wood under moderate leaching conditions, while the use of CZC under such conditions is not recommended.
V N Sozonova, D A Belenkov

Effects of the addition of polyethylene glycol to the CCA-C preservative treatment
1985 - IRG/WP 3337
A modification of the CCA-C wood preservative system for utility poles has been investigated to see if spur penetration into the poles is assisted during climbing. Addition of polyethylene glycol to the CCA system has been shown to accomplish this purpose. This paper addresses the effects of the addition of polyethylene glycol to other physical properties germane to utility poles.
W P Trumble, E E Messina

Tests on the effectiveness of concentrated borate wood preservative
2009 - IRG/WP 09-30500
Tests were carried out to examine the toxicity of concentrated borate wood preservative to termites, fungi and mammals. The results showed that the preservative treated timber had high resistance to termite or decay and its acute oral toxicity belonged to low grade. The research shows that concentrated borate solution is an environmentally sound preservative and can be used in non-pressure treating.
Su Haitao, Zhang Yanjun, Xie Guijun, Chen Lifang, He Xuexiang

A chemical and mycological evaluation of fused borate rods and a borate/glycol solution for remedial treatment of window joinery
1983 - IRG/WP 3225
The possibility of using fused borate rods (Impel Borpatron) and a borate/glycol solution (Boracol-40) for depot impregnation of window joinery has been examined in a co-operative project between The Swedish Forest Products Research Laboratory, The Swedish University of Agricultural Sciences and Prolignum AB. The fused Impel rod is a glassy rod composed of disodium octaborate which readily dissolves and is distributed as bore acid when introduced into moist timber. Boracol-40 is a liquid containing disodium octaborate dissolved in glycol which has an ability to disperse in timber with a moisture content below 25%. The study involved treatment of a large number of windows in service as well as chemical and biological laboratory tests on the distribution and protective effect of the preservatives. In the field study about 100 windows, selected at random in various buildings in the Stockholm and Gothenburg areas were treated in-situ.
M-L Edlund, B Henningsson, A Käärik, P-E Dickèr

Preservative-efficacy of boric acid-triethanol amine solution against wood-decay fungi
1994 - IRG/WP 94-30050
Laboratory preservative-efficacy tests were conducted using boric acid-triethanol amine (BTEA) solution in accordance with the JIS A 9201 (1991) test method excluding the standard weathering process. Sapwood specimens of Picea jezoensis or Fagus crenata to achieve nominal retentions of 0.40-41.2 kg/m³ of boric acid were exposed to Tyromyces palustris, Coriolus versicolor, Serpula lacrymans or Chaetomium globosum, respectively. Mean percentage mass loss data showed the following threshold values: 1.65-2.13 kg/m³ for Tyromyces palustris; 1.60-1.94 kg/m³ for Coriolus versicolor; 0.43-0.83 kg/m³ for Serpula lacrymans; 8.0-23.8 kg/m³ for Chaetomium globosum. The values against Coriolus versicolor and Serpula lacrymans were lower than those of Tim-Bor® as boric acid retention.
S Doi, M Mori, Y Mineki

Incomplete fixation of chromium in the pre-treated wood with a solution of copper and arsenic compounds
1995 - IRG/WP 95-50052
Ponderosa pine wood thin sections were treated with a combination of chromium, copper, and arsenic chemicals. The wood sections was analyzed by electron spin resonance spectrometry (ESR) and X-ray photoelectron spectrometry (XPS) to elucidate the mechanism of fixation of the chromated-copper preservatives. The wood subjected to the two-step treatment with copper and arsenic followed by chromium exhibited a strong Cr(V) ESR signal. However both Cr(III) and weak Cr(V) signals were observed in wood subjected to the one-step treatment containing chromium, copper, and arsenic. XPS spectra also supported the Cr(V) formation in the former treatment. The further chromium reduction from Cr(V) to Cr(III) for samples treated in two steps did not proceed very well during the fixation period of 3 months. Copper arsenate formed in the wood could disturb the interaction of chromium with the wood. These results indicate that re-treatment of wood with chromium containing preservatives may result in incomplete fixation of chromium.
J N R Ruddick, K Yamamoto, F G Herring, P C Wong, K A R Mitchell

Wood surface pretreatments with metal tannates
1989 - IRG/WP 3552
The sequential application of aqueous solutions of tannins derived from radiata pine bark and water-soluble metal salts was examined as a means of improving the water repellency of wood surfaces. Nine metal salts were screened in combination with tannin solutions and, based on water repellency of pretreated filter paper, four were selected for further study. The two-step application of tannin solution and copper acetate solution resulted in water repellency on paper or wood surfaces that compared favourably with that introduced by a chromic acid control treatment. Leaching studies showed that significant quantities of the metal complexes precipitated on the wood surface could be removed by water leaching. Further work is now in progress to evaluate the exterior performance and photostability of the surface pretreatments.
D V Plackett, D R Cronshaw

Determination of boron levels in solution and in treated wood
1994 - IRG/WP 94-20041
Four methods of measuring boron levels in solutions were investigated. The methods compared included the azomethine-H method which is commonly used in soils and plant tissues, the methods outlined in the Australian Standard AS 1605 (1974) and in Wilson (1958), and the atomic absorption spectrophotometry method. Defect-free radiata pine (Pinus radiata D. Don) sapwood and wood flakes were treated to different percentage boric acid equivalent (%BAE). A slightly acidic aqueous medium was used to extract boron from the samples. Extracts were analysed using the azomethine-H and carmine methods. The recovery and coefficient of variation were calculated and discussed. Results confirmed that all methods can be used for measuring boron in solution and wood samples at the range of%BAE investigated. However, the azomethine-H method was found not only to be the simplest and quickest but the most accurate method. It was also found that wood extractives in the wood did not affect the results.
F J Romero, P Vinden, P Kho

Soil treatment tests with the three products of boric acid for the prevention of the hyphal growth of Serpula lacrymans
1992 - IRG/WP 92-3693
Laboratory soil treatment tests were conducted for the evaluation of fungicidal or fungistatic effect of boric acid products against Serpula lacrymans. Boric acid products tested were the following three: a thickened boric acid solution in triethanolamine, boric acid-silica gel complex granules, and a nonwoven fabric laminated with a polypropylene film and coated with boric acid granules on one side surface. Effects of these products were evaluated using ezomatsu (Picea jezoensis) wood blocks and Kanuma soil or unsterilized sandy loam as a soil substrate. The thickened boric acid solution exhibited the sufficient efficacy to suppress the hyphal growth and decay of wood with boric acid retention of 2.0 kg/m³ in Kanuma soil medium. The perfect effect of the boric acid-silica gel complex granules was shown with boric acid retention of 3.0 kg/m³. The hyphal growth of the fungus was almost inhibited by placing the nonwoven fabric with boric acid granules over the media incubated with the fungus.
S Doi, A Yamada, Y Mineki, M Mori

Moderate temperature fixation of CCA-C
1989 - IRG/WP 3522
Several Canadian treating plants are using moderate temperature (40-60C°) fixation chambers to reduce drippage and leaching from fresh CCA treated wood. In this study, chromium reduction and surface leaching properties of CCA-C treated red pine (Pinus resinosa) pole sections were monitored during exposure to temperatures of 50-60C° and 90-100% RH conditions. Chromium-VI concentration in the absorbed treating solution dropped significantly during the treating cycle to 50-60% of that in the free treating solution. The chromium-VI concentration also dropped with increasing depth in the pole. During the six to 24 hour fixation cycle the Cr-VI concentration dropped steadily especially in the outer layers of the pole, but even after 6 hours, a significant amount of Cr-VI was observed at all measured depths. After 12 hours, Cr-VI was only barely detectable at all depths. The leachate analyses were consistent with the Cr-VI results, indicating reduced but still significant surface losses while Cr-VI could still be detected.
P A Cooper, Y T Ung

Silicic acid-Boric acid complexes as wood preservatives
2001 - IRG/WP 01-30273
A silicic acid monomer aqueous solution (SAMS) or colloidal silicic acid solution (CSAS) was combined with various metal compounds or boric acid. Agents where SAMS or CSAS was combined with boric acid gave good protection against decay caused by the brown-rot fungus Fomitopsis palustris, the treated wood (Cryptomera japonica D. Don) specimens after the leaching test maintained a high resistance to decay. The leaching and decay tests revealed high quantities of chemicals leaching from wood treated with SAMS-metal agents. However, when wood was treated with SAMS-boric acid, there was little leaching of agent in either test. The mechanism of resistance of wood, which was treated with boric acid mixed with CSAS or SAMS, to the brown-rot fungus F. palustris were investigated. When the concentration of boric acid was high, mycelial growth was inhibited completely and no protein production was detected. When the amount of boric acid was low, the xylanase, mannase and cellulase activities were lower than with control wood powder. When wood was treated with silicic acid only, its resistance to termites increased, but not to the marked extent observed after treatment with a mixture of silicic and boric acids. Also, increasing the quantity of boric acid increased the mortality rate of termites, and shortened the time to death. From field tests on stakes over three years, it was shown that even if stakes were placed near the termite exit, those treated with silicic acid and high levels of boric acid maintained their original form. Combustion tests showed that with high levels of boric acid, flaming and glowing combustion times were shortened. When boric acid-methanol solution was added at of rate of not less than 25 ml for 100 ml of CSAS, flaming and glowing combustion were not observed. Though the charring length of the wood- specimen, which was treated with silicic acid¡boric acid agent, decreased to 1/3 of that of control wood, the charring lengths were not influenced by the level of boric acid. However, the volume of smoke decreased relative to the amount of boric acid that had been added. When powdery boric acid was combined with CSAS, it was considered that the treated woods have higher anti-weather properties than when boric acid-methanol solution was mixed with CSAS. The agent- preparation method adopted should be considered carefully after taking the treatment process and the intended use of the preservative-treated wood into account.
H Yamaguchi

Biological resistances of wood-metaborate composites using the borax solution system
2001 - IRG/WP 01-30259
Combinations of wood and metaborate composite were prepared from sapwood specimens of Japanese cedar (Cryptomeria japonica) and the borax and metallic salts system using the diffusion-penetrated process. Wood-metaborate composites were produced as follows: water-saturated specimens were first impregnated by a saturated borax solution and then diffuse-penetrated with Zn2+, Ca2+, or Pb2+ solution. Biological resistances of the composites as well as their leachabilities were evaluated. The precipitates of three kinds of metaborates in the wood proved to be insoluble in water by the leaching test. In the decay test using a brown-rot fungus (Fomitopsis palustris) and a white-rot fungus (Trametes versicolor) and in the termite test using a virulent subterranean termite (Coptotermes formosanus), the composites showed generally excellent decay and termite resistances with the negligible weight losses of specimens. Particularly, the lead metaborate formed in the wood provided a superb biological resistance against decay and termite attacks. In addition, the precipitates of these metaborates were found to be soluble in the acidic solution, suggesting a possible way of the easy removal of chemicals from the wood for disposing of wasted composites.
Liang Lin, T Furuno

Tilting and vacuum treatment - two methods to obtain a non-dripping freshly treated timber
1989 - IRG/WP 3535
Modern impregnation plants are designed to prevent spread of impregnation solutions from the plant through leakage, etc. It is also important that freshly treated timber does not spread solutions through dripping on the storage area. To prevent this, the impregnation procedure is terminated with a vacuum period. In many plants in Sweden this period is minimized or even excluded to gain time. Instead the freshly treated timber is tilted for some time before it is transported to the storage area. To evaluate the effect of these two methods to get a non-dripping freshly treated timber a small study was carried out by the Swedish National Testing Institute (SP) together with the Swedish Wood Preservation Institute (SWPI).
I Johansson, M-L Edlund

Thickened boron treatment
1990 - IRG/WP 3632
Commercial trials with thickened boron preservatives "Diffusol™" indicate a number of advantages when compared to traditional methods of dip-boron preservative treatment. These include: (i) more even uptake and distribution of preservative on and within the timber; (ii) faster diffusion times; (iii) the treatment of gauged timber (though improved retention); (iv) saving in energy costs (heating of boron solutions no longer necessary and no burner maintenance); (v) improved sapstain and mould control during diffusion storage; (vi) the treatment of surface dry timber - overcoming the hydrophobic properties of surface dry timber; (vii) antisapstain formulated at time of manufacture - improved quality control and effectiveness; (viii) delivered as liquid - no bags to dispose of, no dust generated from emptying bags; (ix) reduced antisaptain chemical breakdown as solution is used at ambient temperature; (x) assistance in the treatment of high resin content species e.g., Pinus elliottii; (xi) reduced solution degradation (from wood sap diffusing into the solution); (xii) reduced aerosol effect during stacking; (xiii) cheaper manufacture - there is no costly flashing-off of moisture to produce powder boron preservatives. Forty timber preservation plants in New Zealand have adopted "Diffusol" in the first year of commercialisation.
P Vinden, J A Drysdale, M Spence

Solution stability and Mechanical properties of Chitosan treated Pine
2005 - IRG/WP 05-30377
During the last years the research on chitosan as a wood preservative has been enhanced. Up to now, most of the research has been applied to the anti-fungal properties of chitosan, and no research was conducted on the solution stability of chitosan solutions in repeated trials by impregnation of wood, or on the mechanical properties of chitosan-treated wood. In this paper, the stability of high- and low-molecular weight chitosan solutions (2,4% (w/v) concentration) was investigated in 15 repeated impregnation cycles using pine (Pinus sylvestris) samples. Changes in the following parameters of the treatment solution were examined: uptake of chitosan, viscosity, pH, molecular weight and concentration. In addition, the following mechanical properties of chitosan-treated pine were determined using a paired experimental design: modulus of elasticity (MOE), static bending, impact bending strength, static hardness, shear strength, tensile strength, compression strength and adhesion of paint to wood. Overall, an average chitosan uptake by the pine samples in the order of 15 to 16 kg/m³ was obtained. In the trials for determination of solution stability, the uptake, viscosity and concentration remained unchanged. However, the pH of the solutions increased, and the average chitosan molecular weight decreased, with the high molecular weight chitosan displaying larger changes than low molecular weight chitosan. No significant changes in the mechanical properties of pine treated with high-and low molecular weight chitosan (2,4% (w/v) concentration) were determined as compared to untreated wood samples.
E Larnøy, M Eikenes, H Militz

Effects of the sulfuric acid modification of CCA treating solution
1987 - IRG/WP 3415
Sulfuric acid modification of CCA treating solution is often used to control the formation of sludges and undesirable deposits on the surface of treated wood. The consequences of sulfuric acid addition are examined in this work and negative effects are shown to far outweigh any benefits. Major risks include the loss of copper due to leaching from treated wood and the accelerated corrosion of treating equipment when even small quantities of sulfuric acid are employed. Twenty-year stake test results demonstrate that the addition of as little as 0.5% by weight of sulfuric acid to CCA treating solution can result in premature field failure. A mechanism for the effects of sulfuric acid on the chemistry of this system is discussed.
R F Fox, H J Fry, E A Pasek, A S Ross

Arsenic removal by plant pumping mechanism from arsenic solution using activated aluminum oxide as adsorbent – a preliminary study
2006 - IRG/WP 06-50239
This study evaluated the performance of plant pumping mechanism for removal of arsenic from arsenic solution using activated aluminum oxide as adsorbent. Generally, plants absorb water from soil mainly by osmosis process and toxic elements present in soil also move along with water. To remove toxic elements present in contaminated soils/water, different chemical substances are widely used as adsorbents. In the current study an attempt has been made to remove arsenic using activated aluminum oxide by plant pumping mechanism and it has removed about 97% of arsenic in 16 days.
B Tarakanadha, H Koyanaka, T Hata, Y Imamura

Sorption properties of wood impregnated with aqueous solution of boric acid and montan wax emulsion
2010 - IRG/WP 10-40492
Non-biocidal techniques for wood protection become more and more important, nowadays. One of the possible treatments is use of water repellents. In the present research influence of, one of the possible water repellent, the montan wax emulsion, on the moisturizing and the sorption characteristic of impregnated wood was investigated. To achieve a better protection against wood decay fungi, montan wax emulsion enriched with boric acid, was used for impregnation of wood. The equilibrium moisture content (EMC) during the adsorption and the desorption process at five levels of relative humidity (φ1 = 20%, φ2 = 33%, φ3 = 65%, φ4 = 88% and φ5 = 98%) was monitored. Water repellence efficiency was monitored in the chamber with high relative air humidity (87%) and during dipping in the water. Impregnated samples were also exposed outdoor in cowered position for five months. The results showed that the sorption properties of the impregnated wood are strongly related to retention of preservative solutions after impregnation and its compositions. Montan wax reduced equilibrium moisture content of the impregnated wood up to 25% while specimens impregnated with combination of montan wax and boric acid in some cases resulted in the decreased and in some cases in the increased EMC. The Guggenheim-Andersen-deBoer (GAB) model of sorption isotherms was fitted to experimental data to explain the sorption mechanisms.
B Lesar, M Humar

Preservative Treatment of simul (Bombax ceiba) Veneers with Hot and Cold Water Solution of borax-boric acid by Soaking Process
2010 - IRG/WP 10-40528
Veneers of simul (Bombax ceiba) were treated with different concentrations of water- borne preservatives borax-boric acid (BB) by soaking process for different time periods. In the case of hot water treatment, it was found that the average retention of preservative chemicals increased gradually with the increasing treatment period from 20 minutes to 60 minutes. Similar trend was observed in the case of cold water treatment when treatment period was increased from 1 day to 3 days. The maximum retention (20.37 kg/m3) was observed from the samples treated with 10% BB solution for 60 minutes and in 2.5% BB treated samples, the average retention gradually increased from 5.35 kg/m3 to 7.16 kg/m3 when treatment duration was varied from 20 to 60 minutes. In the case of cold water treatment, maximum retention (22.97kg/m3) was observed from the veneers treated with 10% BB solution for 3 days and 7.35 kg/m3 retention was obtained when treated with 2.5% Borax-boric acid solution for 1 day. According to the Indian Standard (IS-1902), the retention of 4 kg/m3 boron compounds are sufficient to offer protection for non-structural purposes.
K Akhter, Md Abul Hashem, S Akhter

Smart hydrogels from low molecular weight amphiphilic compounds: toward a solution to decrease leachability and increase efficacy of boron preservatives?
2012 - IRG/WP 12-30589
A new catanionic system associating amphiphilic carnosine (AlaHisC8) and lauric acid forms supramolecular hydrogel at very low concentration. This gel was investigated and we have checked the validity of the concept of hydrogels utilization to reduce boron leachability and to develop new wood protection treatments. Impregnation with 5% aqueous borax solution (w/w) and 0.3% gelator agent (w/w) allows to improve resistance of Scots pine sapwood subjected to water leaching towards the brown rot fungus Poria placenta, while samples treated with 5% aqueous borax solution were partially degraded by the fungus. These results clearly indicate the effectiveness of hydrogel to retain boron in wood.
F Obounou Akong, P Gérardin, C Gérardin-Charbonnier

Study on the Effect of Combined Nanosilver-Hygrothermal Treatment on Wood Properties
2012 - IRG/WP 12-40581
In this study, the impregnation process with nanosilver solution, before hygrothermal treatment was carried out to investigate its effect on some physical and mechanical properties of Iranian beech (Fagus orientalis Lipsky) and Russian imported spruce (Picea abies). Wood specimens were impregnated with nanosilver solution (400ppm) in an impregnation tank under pressure of 0.25 Mpa, for 20 minutes. Hygrothermal treatment was carried out at the temperatures of 120, 150 and 180ºC for 1, 3 and hours. One group of specimens was only hygrothermally treated and considered as controls. Values of volumetric swelling after 24 hours soaking in water, bending strength, impact load resistance and compressive strength parallel to the grain were measured. The results showed that by increasing the temperature of hygrothermal treatment volumetric swelling and mechanical properties of specimens were decreased. The duration of treatment has no significant effects on mechanical properties. Also, in wood specimens which were impregnated with nanosilver solution and treated at 180ºC, volumetric swelling were lower than controls, without any significant decrease in mechanical properties. On the whole, it could be said that with nano silver impregnation of wood, hygrothermal treatment can be carried out at higher temperature (180ºC) to achieve better dimensional stability with no more decrease in mechanical properties.
G Rassam, H Reza Taghiyari, A Karimi, B Jamnani, M Ebrahimi

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