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Wood kiln drying. Simple process of material treament or soft method of preservation? (Le séchage arificiel du bois. Simple opération de traitement du metériau ou méthode douce de préservation?)
1993 - IRG/WP 93-50001-14
Among the processes enabling to extend wood durability, kiln drying can be considered as a treatment and soft preservation method. Dry woods are naturally durable provided they are not subject to important retaking of the moisture. Drying thanks to the application of temperatures from 50 to120°C enable to execute a thermic treatment which kills grubs and mushrooms to ensure a sterilization that can be durable if wood doesn't retake water. Noumerous connections and analogies between drying process and the preservation one enable to conclude that kiln drying is a real operation of wood treatment either curative or to a smaller extent preventive.
F More-Chevalier

Copper naphthenate-treated Southern Pine pole stubs in field exposure. -Part 2: Chemical characterization of full size pole stubs 12 years after treatment
2000 - IRG/WP 00-30246
This study examines the influence of pre-treatment and post-treatment steaming on the character and physio-chemical nature of copper naphthenate in hydrocarbon solvent treated pine in larger, pole diameter, pole stub-length samples. This work is the continuation of two projects that began almost a decade ago. Previous reports indicated that certain morphological changes might occur in small laboratory steamed samples of copper naphthenate treated southern pine. Toluene-methanol extraction, UV-Vis spectroscopy, X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM) were used to investigate the nature and properties of the copper naphthenate present in the wood after 12 years of exposure. The formation of solid cuprous oxide occurred regardless of pre- or post-steaming conditioning.
H M Barnes, D P Kamdem, M H Freeman

Heat treated timber in Finland
2000 - IRG/WP 00-40158
Heat treatment permanently changes the physical and chemical properties of wood by means of high temperatures (150 - 240°C). Heat treatment darkens the colour of the wood. Heat treatment improves the equilibrium moisture content of the wood and the shrinkage and swelling of the wood is reduced. Very high temperatures improve the resistance to rot and also reduce the susceptibility to fungal decay. At the same time the strength properties of the timber are reduced: the bending strength can fall by 30%, depending on the treatment conditions and the cleavage strength (tensile strength perpendicular to fibres) may be reduced to a half, which makes heat treated timber split easily. The improved characteristics of heat treated timber offer the timber product industry many potential and attractive new opportunities. Also wood species having no commercial value as such can be heat treated and in this way new uses can be found for these species.
T Syrjänen, E Kangas

Investigation of some technical properties of heat-treated wood
2003 - IRG/WP 03-40266
The objective of this study was to investigate some technical properties of heat-treated wood. Wood heat-treated according to a process intended for wood in above-ground end-uses (European hazard class 3) was subject to the following: · A delamination test according to EN 391 with glulam beams made of heat-treated pine (Pinus sylvestris) and spruce (Picea abies) laminations, assembled with PRF and PVAc adhesive respectively. · Determination of the withdrawal load for screws and nails. · Determination of the emission factor for VOC and the identification of major compounds. Results: · PRF adhesive performed very well whereas PVAc adhesive showed an unacceptable percentage of delamination and thus seems to be unsuitable for gluing heat-treated wood. · There is an indication that the withdrawal load for heat-treated wood is generally lower than for untreated wood. However, the number of tests carried out was quite small and definitive conclusions are difficult to draw. · The emission factor for the heat-treated wood, expressed as TVOC, was less than 10 µg/(m2 x h) and this was less than for untreated reference.
C Bengtsson, J Jermer, A Clang, B Ek-Olausson

Effects of a formaldehyde and sulphur dioxide treatment on decay and mechanical properties of aspen waferboard
1983 - IRG/WP 3242
Aspen wafers were sequentially treated under vacuum with formaldehyde and sulfur dioxide gas and pressed into waferboard bonded with powdered phenol formaldehyde resin. Decay resistance and strength properties were determined before and after simulated weathering. The water resistance of the phenol bonding system was lost in board made from the gas-treated wafers. This white rot fungus Coriolus versicolor was unable to decay treated waferboard in a soil block test, but the brown rot fungi Gloeophyllum trabeum and Poria placenta decayed the samples as severely as untreated controls.
E L Schmidt

Chemical Analysis of Southern Pine Pole Stubs Thirty-Nine Months Following Treatment with Three Methylisothiocyanate-Based Fumigants
2004 - IRG/WP 04-30349
Agricultural fumigants have been commercially used in the United States for over 20 years to control internal decay in utility poles and other wooden structures. Of the four fumigants which are currently used in the remedial treatment of utility poles, three are based on methylisothiocyanate (MITC) as being the principal fungitoxic component. Two of these MITC-based fumigants, liquid metham sodium and granular dazomet, chemically decompose within a utility pole to release methylisothiocyanate. The third MITC-based fumigant consists of 97% methylisothiocyanate in a solid melt form. Laboratory and field studies conducted as part of the Cooperative Pole Research Program at Oregon State University have demonstrated the efficacy of all three MITC-based fumigants. However, studies conducted to date have not evaluated the three fumigants under the same experimental conditions. As a result, a field study of the three commercial MITC-based fumigants was established in June, 2000 in southern pine utility pole sections. At the second inspection conducted 39 months following fumigant treatment, chemical assay borings were removed at various pole heights and depths and analyzed for concentrations of MITC using GCMS. The 39 month results showed that MITC concentrations were greatest at all pole heights and core depths in the pole stubs treated with the 97% MITC product. In addition, similar concentrations of MITC were found in the metham sodium and dazomet treated pole stubs. When compared to the corresponding chemical assay results at 13 months following fumigant treatment, the 39 month results showed a sharp increase in concentrations of MITC in the 97% MITC treated pole stubs and a sharp decrease in MITC concentrations in the metham sodium treated pole stubs. MITC concentrations remained relatively unchanged in the dazomet treated pole stubs from 13 to 39 months following fumigant treatment. When compared to a MITC threshold value for decay fungi proposed by Oregon State University, the chemical assay results at 39 months indicated all three fumigants are effectively protecting the zone of fumigant treatment (15.2 cm below to 15.2 cm above groundline) of southern pine pole stubs. However, the greatest protection within and above the zone of treatment was provided by the 97% MITC treatment. Future sampling and chemical analysis of the southern pine pole stubs are planned to monitor long term efficacy of the fumigant treatments.
R J Ziobro, J Fomenko, D J Herdman, J Guzzetta, T Pope

Practical consequences of the clarification of the chemical mechanism of CCA fixation to wood
1983 - IRG/WP 3220
Practical consequences derived from the chemical investigation of the mechanism of fixation of CCA to the wood constituents are discussed. Among these, formulas for the calculation of the time of hexavalent chrome fixation are presented. Furthermore, three parameters are shown to be important to the long-term effectiveness of CCA-treated timber: (i) the temperature of treatment, (ii) the initial pH of the CCA solution and (iii) its concentration. Variation in the values of these three parameters cause drastic differences in the distribution between lignin and holocellulose of the preservative chemicals which will considerably affect the durability of CCA-treated timber. New, more economical and more effective application schedules and CCA formulations both in chemical composition and requiring lower retentions (softwoods) and imparting equal or superior durability to the treated timber can be devised from the results presented. From the results it appears that CCA formulations producing better soft-rot resistant hardwoods can be devised and the changes necessary to obtain this, are outlined.
A Pizzi

Treatability problems - Relationships between anatomy, chemical composition and treatability
2001 - IRG/WP 01-40213
This report documents the results of phase 1 and 2 of a 3-phase research program. In phase 1, two hundred and fifty-six (256) Southern pine (pinus spp.) nominal 2 x 6's (38 mm x 140 mm) from a single mill in Georgia (southeastern US) were evaluated for treatability with CCA preservative. After treatment, 128 pieces representing a broad range of treatment characteristics were selected and more fully evaluated for anatomical and chemical composition. No direct correlation was noted between CCA treatability and any of the anatomical characteristics evaluated in this study. Neither did a direct correlation between chemical composition and treatability seem to exist. The pit tori of all pits evaluated in this study were aspirated against the pit wall for this difficult to treat Southern pine lumber. This pit aspiration might have resulted from pre-treatment kiln drying. Later reductions in kiln temperature and increased kiln humidity (i.e., lowered wet-bulb depression temperature) reportedly resulted in improved treatability. In Phase 2, a methodology was developed to assess treatability after 3 treating schedules and then compare those results to permeability measurements and anatomical characteristics of matched material from 7 growth regions.
J E Winandy, F Green III, D Keefe

Properties of hot oil treated wood and the possible chemical reactions between wood and soybean oil during heat treatment
2005 - IRG/WP 05-40304
Thermal treatment with hot oil as the heating media based on the original idea from oil-heat treatment in Germany was investigated. The treatment was mainly carried out at 200ºC and 220ºC for 2 hours and 4 hours, and the wood species were mainly spruce and fir. This paper focuses on the difference between soybean oil and palm oil and the possible chemical reactions between wood and soybean oil. Generally palm oil was slightly better than soybean oil in improving the moisture resistance properties of heat-treated wood. But soybean oil treated wood appeared to have better decay and mould resistance. The mass loss of wood treated in soybean oil at 220ºC for 4 hours was below 20 % after exposure to Gloeophyllum trabeum in a soil block test, so the treated wood can be classified as “Resistant” according to ASTM D 2017 standards. Natural weathering exposure also shows that soybean oil treated wood is more mould resistant than palm oil treated wood. In order to investigate the effects of absorbed oil on the properties of treated wood and the possible reactions between wood and oils, extraction of different vegetable oil treated wood with chloroform and other solvents was carried out. The results suggest that part of the soybean oil could undergo chemical reactions with wood that renders it of low extractability.
Jieying Wang, P A Cooper

Improvements of stability and durability of beechwood (Fagus sylvatica) by means of treatment with acetic anhydride
1991 - IRG/WP 3645
In the present investigations, beechwood (Fagus sylvatica) was treated with non-catalysed acetic anhydrid at 120°C and some physical- and biological parameters of the treated wood were compared with those of non-treated wood. The radial and tangential shrinkage and swelling, respectively, and the absorption capacity of the acetylated wood against moisture is considerably lower. The durability against fungi improves. The results are discussed.
H Militz

Preliminary results of the treatment of wood with chlorosilanes
1981 - IRG/WP 3172
It is clear from the initial data reported here that the treatment of pine sapwood with chlorosilanes under the reaction conditions employed did not significantly reduce the decay by both white rot and brown rot fungi. Only the dichlorosilane compounds showed to possess some protective action against fungal attack. Before drawing conclusions on the application of organosilicon compounds as potentially alternative wood preservatives much more work is needed. At present the anti-blue stain activity of the different types of chlorosilanes is being tested. Further investigation on the treatment is also required with respect to the effect of wood moisture content and the use of other types of acid acceptor on the silylation reaction. Current studies also deal with the effect of the treatment on physical and mechanical properties of wood. The initial physical tests on the sorptive and dimensional behaviour of treated wood revealed that the dichlorosilanes might give better results again.
M Stevens

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

Chemical evaluation of borate treated pine sapwood attacked by the subterranean termite Coptotermes acinaciformis
1993 - IRG/WP 93-20003
Sapwood of hoop (Araucaria cunninghamii Ait. ex D. Don) and slash (Pinus elliottii Englem.) pines were treated by Vacuum Pressure Impregnation (VPI) to provide test specimens. The concentration of boron was defined by chemical analyses of the timber, in the zone of primary attack by the termite being bioassayed. A common method of definition of preservative retention, weight uptake of preservative fluid of known concentration, was compared to the chemical assay method for slash pine treatments. Analyses of gradient zones reflect the variable concentration of boron within test specimens. The test specimens were exposed to field termite colonies in a clear of ground completely protected from weather and wetting situation. Termite response was determined by mass loss over 5 weeks and modelled.
A R Moffat, B C Peters

Effects of alkali treatment on some mechanical and chemical properties of creosote treated oaks
1991 - IRG/WP 2366
To date, there is a lack of information on the effects of chemical treatment on the performance of creosote preservative treated oak sleepers. This factorial experiment was designed to analyze three main effects: species (Quercus alba and Quercus rubra) creosote treatment (treated and untreated), and alkali (NaOH) soaking (0, 1, and 10 percent). The modulus of elasticity (MOE) and fiber stress at proportional limit in compression perpendicular to grain, hardness modulus, surface hardness, alcohol-benzene extractives, hot-water extractives, 1% NaOH extractives, lignin, pentosans, holocellulose, and alpha-cellulose content were determined on specimens. The test results indicated that species, creosote treatment, and alkali soaking significantly affect both the mechanical and chemical properties of the oak sleepers.
P Chow, A J Reinschmidt, E J Barenberg, L C Chang

Remedial ground-line treatment of CCA poles in service. Results of chemical and microbiological analyses 6 months after treatment
1986 - IRG/WP 3388
CCA-treated poles in service with incipient internal soft rot were remedially treated by inserting borate rods, brushing with a boron/glycol solution and injecting boric acid paste, copper/creosote paste or a commercial product (DFCK paste). The spread of active chemicals in the treated zone as well as the change in microflora have been studied with time. After six months chemicals had spread to most parts of the pole in the ground-line zone and the microflora had been changed - in some cases drastically. The test is still in progress. Chemical and microbiological analyses after 12, 28 and 60 months will be published at a later date.
B Henningsson, H Friis-Hansen, A Käärik, M-L Edlund

Preservative treatment and field test monitoring of spruce pole stock: Pressure and diffusible chemical treatments
1990 - IRG/WP 3605
One hundred and forty four spruce (test species) and southern yellow pine (reference species) poles were variously treated by center boring, incising, or kerfing, followed by pressure treatment with CCA and/or diffusible preservatives. The diffusible preservatives included NaF/creosote, borax and ammonium bifluoride. The poles were set at a test site and evaluated for preservative distribution and fungal invasion after one year of exposure. A narrow incising pattern was needed to obtain adequate CCA penetration even when a 'pulsation' pressure treatment schedule was used. Of the internally applied diffusible preservatives, both borax and ammonium bifluoride were found to diffuse successfully throughout the groundline region of the spruce pole stock. This treatment prevented invasion of decay fungi into the poles. A low incidence of fungal attack was observed in the CCA treated spruce that had been kerfed but not additionally treated with diffusible preservatives. Although additional years data are needed to make definitive recommendations, protection of spruce poles appears to be achievable through the use of either kerfing, or diffusible chemical treatment, in incised/CCA pressure treated stock.
B Goodell, A J Pendlebury

Chemical treatment of ten Amazonian timber species of low natural durability
1991 - IRG/WP 3640
The objective of this work was to evaluate the performance of 10 amazonian wood species of low natural durability, to treatment with CCA preservative (2% concentration): it was concluded that all species studied are easily treated with this preservative. The sapwood showed high absorption and total penetration. The heartwood is relatively easy to preserve, exception to Parkia nitidae (Fava), Qualea paraensis (Mandioqueiras), Erisma unicatum (Quarubarana), and Virola sp (Ucuúba), which presented some restrictions. Nevertheless, it does not mean that their treatment is impossible.
C S Neta, B F Vianez

The effect of chemical treatment on the moisture distribution of Pinus radiata D.Don subjected to wick action
1999 - IRG/WP 99-40135
Radiata pine sapwood stakes were treated with a range of chemicals, including an ammoniacal copper quaternary ammonium compound (ACQ), a copper-chrome and arsenic (CCA) solution and a CCA-oil treatment, potassium linoleate copper linoleate, a paraffin wax and a proprietary alkyd resin. The effect of these treatments on the extent of water absorption and moisture movement through the stakes was investigated. Results indicate that pre-treatments could affect uptake and flow of water through the wood, which in time could be attributed to the properties of the solutions and whether they had surface active, bulking or water repellent attributes.
J Hann, P Vinden

Silafluofen: Novel chemistry and versatility for termite control
1995 - IRG/WP 95-30069
A novel silicon - containing insectizide, HOE 084498 ('Silafluofen'), with a favourable toxicological profile, has shown activity against a broad spectrum of agricultural and environmental health pests. Results from laboratory and field studies around the world have demonstrated that silafluofen is effective at protecting timber from attack by various species of termite and wood-boring beetle. As a termiticide, silafluofen, applied as a dust-toxicant, may suppress/eliminate Coptotermes sp. Ongoing field trials in France, in cooperation with CTBA, indicate that silafluofen, injected directly into masonry, has controlled Reticulitermes santonensis. No signs of termite activity have been observed in the treated part of an infested house since the application was made, 2 years ago.
A J Adams, A Jermannaud, M-M Serment

Chemical Analysis of Southern Pine Pole Stubs Thirteen Months Following Treatment with Three Methylisothiocyanate Based Commercial Fumigants
2002 - IRG/WP 02-30294
Agricultural fumigants have been commercially used in the United States for over 20 years to control internal decay in utility poles and other wooden structures. Of the four fumigants which are currently used in the remedial treatment of utility poles, three are based on methylisothiocyanate (MITC) as being the principal fungitoxic component. Two of these MITC based fumigants, liquid metham sodium and granular dazomet, chemically decompose within a utility pole to release methylisothiocyanate. The third MITC based fumigant consists of 97% methylisothiocyanate in a solid melt form. Laboratory and field studies conducted as part of the Cooperative Pole Research Program at Oregon State University have demonstrated the efficacy of all three MITC based fumigants. However, studies conducted to date have not evaluated the three fumigants under the same experimental conditions. As a result, a field study of the three commercial MITC based fumigants was established in June, 2000 in pentachlorophenol treated southern pine utility pole sections. At the first inspection conducted 13 months following fumigant treatment, chemical assay borings were removed at various pole heights and depths and analyzed for concentrations of MITC using GCMS. The 13 month results showed the concentrations of MITC were greatest at all pole heights and core depths in the pole stubs treated with the 97% MITC product. In addition, higher concentrations of MITC were found in the metham sodium versus dazomet treated pole stubs. The results of the initial sampling of the southern pine pole stubs are compared to results of the fumigant efficacy studies conducted at Oregon State University. In addition, the chemical assay results are compared to a proposed MITC threshold value based on the results of the Oregon State University fumigant studies. Future sampling and chemical analysis of the southern pine pole stubs are planned.
R J Ziobro, T C Anderson, D J Herdman, J Guzzetta, T Pope

The effects of preservative treatment and exposure to wood degrading fungi on fiber reinforced polymer (FRP) materials used for structural wood reinforcement
2001 - IRG/WP 01-40204
Glass fiber reinforced phenolic (GFRP) composite materials are becoming increasingly accepted for use in the construction industry because they combine advantages of both wood and advanced polymeric materials. Addition of only 1-3% FRP in the tension zone, for example, can typically improve the strength of the hybrid system by 200%. As more applications are found for wood/FRP hybrids, (e.g. laminated wood for bridge applications, waterfront piers) their use in exterior and high-decay-hazard environments would be expected to grow. Since FRPs were designed to be used with wood material for use in exterior exposures, they will be exposed wood preservative chemicals, and to wood decay fungi as well. Therefore, currently developed glass-fiber reinforced phenolic polymer materials for wood reinforcement were examined to determine the effects of wood preservative chemicals and exposure to wood degrading fungi. Several common wood preservative chemicals (oil-and water-borne) were used for treatment of FRP materials. While chemically "fixing" preservatives resulted in significant strength loss, oil-borne preservatives systems did not affect the mechanical properties of the FRP material. When the common brown and white rot fungi (Gloeophyllum trabeum and Trametes versicolor) were used for fungal exposure studies, after 24 weeks of exposure G. trabeum exposed FRP coupons showed reduction in interlaminar shear strength. Scanning electron microscopy (SEM) and fluorescent photomicrograph 58 analysis supported the mechanical test results, indicating that fungal growth and possible consumption of organic sizing material on the wood/fiber interface had occurred. Further studies are underway with different organisms to provide a more detailed explanation of biodegradation mechanisms of FRP composites for wood reinforcement.
C Tascioglu, B Goodell

Chemical treatment of chips for outdoor storage. Evaluation of sodium N-methyldithiocarbamate + sodium 2,4-dinitrophenol treatment
1980 - IRG/WP 2134
Fresh slash pine chips were treated by spraying them with a dilute aqueous solution of sodium N-methyldithiocarbamate and sodium 2,4-dinitrophenol. The were then formed into an experimental chip file 10 feet high, and the pile was maintained for seven months. The treatment effectively slowed heat release and retarded losses in wood substances, tall oil, pulp yield, and pulp strenght. Under certain conditions, use of the treatment may be economically feasable.
E L Springer, M Benjamin, W C Feist, L L Zoch, G J Hajny

Shorter-term biological control of wood decay in pre-seasoning pine roundwood as an alternative to chemical methods
1992 - IRG/WP 92-1555
Previous studies on the long-term control of decay in creosoted transmission poles, using Trichoderma and other antagonistic moulds, have met with limited success. However, it is possible biological control is more suited to control of decay on shorter time scales. An earlier study, focusing on pre-seasoning treatment of transmission poles showed that favourable porosity increases could be brought about by an isolate of Trichoderma. Furthermore, it was evident that considerable improvement could be made in developing antagonistic strains of Trichoderma. A study further investigating the use of antagonistic primary mould fungi as biological control agents is outlined.
M W Schoeman, D J Dickinson

Chromated copper arsenate preservative treatment of hardwoods. Part 1: CCA fixation performance of seven North american hardwoods
1997 - IRG/WP 97-30131
There has been an increased interest in utilisation of hardwoods from eastern North America for exterior applications which require protection with preservatives such as CCA. We have examined CCA fixation at two selected temperatures of seven common North American species: red maple (Acer rubrum L.,), white birch (Betula papyrifera ), yellow poplar (Liriodendron tulipifera L.), trembling aspen (Populus tremuloides ), red oak (Quercus rubra L.), basswood (Tilia Americana ) and beech (Fagus grandifolia Ehrh.). The softwood red pine (Pinus resinosa) was included in all studies for comparison. Chromium fixation was followed by the expressate method at both ambient temperature (21°C) and at 50°C under high humidity (95%) conditions. Cr, Cu and As contents of the expressate were determined by X-ray fluorescence method and chromium (VI) was determined by diphenyl carbazide method at different times during fixation. Based on CCA fixation results it was possible to divide the examined hardwoods into a fast fixing group (beech, red oak and red maple), intermediate group (white birch and red pine) and slow fixing group (aspen, yellow poplar and basswood). Variable fixation rates for the different species are discussed in relation to different densities and different cell wall components and their contents in the different hardwoods.
T Stevanovic-Janezic, P A Cooper, Y T Ung

Resistance of pine and spruce heartwood against decay - The effect of wood chemical composition and coating with water-borne wood oil product
2006 - IRG/WP 06-10597
Natural durability of wood has been widely studied, but the combination of the natural durability and different treatments has not been the focus of many studies. The durability of wooden products is mainly based on the water permeability and the resistance against organisms. In this study, the water absorption and decay resistance of sapwood and heartwood of Scots pine and Norway spruce were examined. The effects of the wood origin and the coating with water-borne wood oil were also observed. The wood oil is penetrating treatment which is recommended for decking and garden furniture. The results were compared to the chemical composition of wood. The water absorption of untreated pine sapwood was significantly higher than that of pine heartwood or spruce. Decay resistance of pine heartwood was relatively high. However, the decay resistance was widely varied among different pine heartwood samples and in some cases this variation was significantly higher than that of pine sapwood or spruce. The effect of wood oil coating on decay resistance of pine heartwood was more significant than on pine sapwood. Elevated decay resistance was also found among coated spruce samples, but no significant difference between sap and heartwood was found. Decay resistance was comparable with water permeability and pinosylvin content of wood.
H Viitanen, S Metsä-Kortelainen, T Laakso

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