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Developments in the protection of wood and wood-based products
1980 - IRG/WP 340
Technology is playing an increasingly important role in the field of wood protection. This current review highlights how modern techniques have provided greater insight into the biological and physical processes affecting the durability of wood and wood-based products. Emphasis is also given to developments in preservative testing methodology and to the encouraging changes towards both the correct use of timber and the improvement of Standards and Codes of Practice. A final section, on recent technical developments in wood preservation, considers subjects ranging from an evaluation of new specific biocides to methods of increasing the permeability of refractory timber species.
J M Baker


A direct method for testing plywood and particle boards against fungal decay
1984 - IRG/WP 2214
A method directly inspired from the French standard testing method of the resistance of particle boards against fungal decay (AFNOR N° 51.295 May 1980) is described. But in that experimentation, the infestation is localized and realized in non sterile conditions. Small blocks of Fagus sylvatica (60 x 20 x 10 mm³) used as " inoculates " are infested with basidiomycetes, in Kolle flask for 4 to 6 weeks, then tightly pressed against the middle part of the test specimens (190 x 15 x 15 mm³). The lower part of the inoculates is plunged in vermiculite kept constantly humid by water containing a selective fungicide. After twelve weeks of exposure in non sterile conditions, in a green house with constant temperature around 20°C, the test specimens are then submitted to a static bending test until fracture. The comparison of the fracture-stress between control test specimens and the specimens exposed to wood rotting basidiomycetes permits to evaluate the resistance of the studied materials against fungal decay.
L N Trong


Effect of water repellents on leaching from CCA treated wood
1995 - IRG/WP 95-50044
CCA treated fence boards brushed with a water repellent finish had consistently lower leaching losses of all CCA components compared to the rate for matched samples without the water repellent. These results are after 12 cycles of simulated rainfall in the laboratory (1800 mm rainfall total) and four months of natural rain exposure in Toronto.
P A Cooper, R MacVicar


Relationship between stacking, location and antisapstain preservatives on visible degrade of Eucalyptus regnans and Pinus radiata boards
1999 - IRG/WP 99-20162
An antisapstain trial was established at a Eucalyptus hardwood sawmill in Victoria, Australia. The trial incorporated two commercial formulations of antisapstain preservatives, used at four different concentrations on both hardwood (Eucalyptus regnans F. Muell) and softwood (Pinus radiata D. Don) boards. The trial also utilised different stacking methods (block-stacked, sticker-stacked, and block-stacked and wrapped in black plastic) and included replicates placed both outside in the drying yard, and inside under cover from the elements. The variation in stacking methods and in location was used to provide a variation in the fungal hazard. Worst degrade (mean of 83% at 36 weeks) was obtained for the hardwood block-stacked outside and wrapped in black plastic. Lesser extents of degrade were obtained for sticker-stacked hardwood outside (4.3%) and sticker-stacked hardwood under cover (1.2%). Degrade of softwood was less than that of hardwood under all conditions. Statistical analysis of the trial indicated that the probability of any individual hardwood board deteriorating outside was nearly 4 times greater than for a board kept undercover. In addition, the probability of degrade of a hardwood board which was block-stacked and wrapped in black plastic was 3.4 times that of a hardwood board which was block-stacked but not wrapped, which in turn was 10 times that of a hardwood board which was sticker-stacked. The probability of degrade in untreated hardwood timber was 20 times that of degrade in preservative-treated hardwood timber, with variations in preservative concentration having an insignificant effect. Over all conditions the probability of hardwood timber deterioration was 5 times that of the softwood. The results of this trial confirmed that timber stored closely stacked and under poorly ventilated conditions suffered a higher visible degrade, as expected for sapstain fungi. However, although preservatives effectively reduced visible degrade under all storage conditions and at all concentrations tested, selection of correct storage conditions was also an important part of minimising degrade.
J Snow, P Vinden, S M Read


Field trials of anti-sapstain products. Part 1
1991 - IRG/WP 3675
The results obtained in two field tests of anti-sapatain products, carried out in four locations in Portugal, are presented. Boards from freshly cut logs were hand-dipped, close staked and left to dry for periods from four to six months. The results obtained seem to indicate that some of the products tested performed at least as well and sometimes better, than a 3% NaPCP solution which was used as control product.
L Nunes, F Peixoto, M M Pedroso, J A Santos


Mycological testing of plywood and board materials. Part 1: Review of information supplied by IRG members
1978 - IRG/WP 284
In December 1975 IRG members were asked for published information, information of current work in progress and views on mycological test methods for board materials. The object was to stimulate discussion and possibly establish a joint research effort within IRG in order to establish a meaningful test with reproducible results.
C R Coggins


European standardization for wood preservation
1990 - IRG/WP 2359
G Castan


Water sprinkled pine wood: A microscope study on boards showing streaking
1993 - IRG/WP 93-10033
Boards sawn from the outer sapwood of pine lumber previously water sprinkled for periods of 10-18 weeks and kiln dried, showed streaking after staining. Two types of enhanced stain uptake were noted: 1) a more concentrated and localized form after 10 weeks and 2) a more diffuse type which developed in later stages of water sprinkling. Areas showing enhanced stain uptake were examined using light and scanning electron microscopy. For all samples, staining was most concentrated in rays (both fusiform and uniseriate) and axial resin canals. Studies suggest that increased permeability and enhanced stain uptake results primarily from microbial (fungal and bacterial) destruction of rays and axial resin canals (i.e. ray parenchyma, epithelia cells, window pit membranes), either by direct attack (i.e. close proximity of bacteria/fungal hyphae) or by diffusion of enzymes (probably cellulases) from microbes distant from sites of hydrolysis. Sapwood offcuts from the outer regions of water sprinkled wood lacking bark showed severe colonization and decay of ray tissues by both bacteria and sapstain fungi. Diffuse stain uptake in boards at later stages of water sprinkling appeared to be secondary and result from bacterial and/or fungal decay of bordered pit membranes.
G F Daniel, T Elowson, T Nilsson, A P Singh, K Liukko


Preservative requirements for exterior particleboard as predicted from accelerated laboratory evaluations
1976 - IRG/WP 265
Arguments for and against preservative treatment of exterior particleboard were considered; it was concluded that preservative treatment is desirable. Laboratory decay tests were conducted to determine levels of sodium pentachlorophenoxide required to protect exterior particleboard from decay fungi. The decay resistance of treated board was compared with that of timber (both naturally durable and preservative-treated) currently used in situations for which exterior particleboard is designed. A retention of 0.35% sodium pentachlorophenoxide per oven-dry board weight was considered to offer adequate protection to the board.
M E Hedley


Biodegradation of acetylated southern pine and aspen composition boards
1994 - IRG/WP 94-40020
This objective of this study was to investigate the influence of the acetylation treated wood fiber, Phenol-formaldehyde resin content level, two wood fiber species, three fungi species on the dimensional stability and decay resistence of high density composition boards. A standard ASTM method was used to evaluate weight loss and thickness change. The linear shrinkage and expansion of each species were also determined. All specimens were exposed to decay chambers for 16 weeks. Test results indicated that most of the main factors significantly influence the thickness and length changes and the decay resistance of the high density composition boards.
P Chow, T Harp, R Meimban, J A Youngquist, R M Powell


The effect of creosote and Basilit on the boards of 4 wood species against destructive fungi in Northern Iran
1989 - IRG/WP 3555
The results of the experiments conducted on the boards of maple, hornbeam, alder and beech, show that under the humid and moderate climate condition of Northern Iran, after 30 months, the witness samples were about 10% destructed by fungi, especially by Schyzophyllum commune and Coriolus versicolor. The impregnated samples by Creosote Basilite using Rueping and Bethell methods, were quite intact. There was no difference between these two chemicals. Among destructed boards, maple and hornbeam containing the most sugar and starch materials are more senitive than beech and alder. Until 50% destruction of witness samples, the experiments will follow up.
D Parsapajouh


The first two years of an area wide management program for the Formosan subterranean termite in the French Quarter, New Orleans, Louisiana
2000 - IRG/WP 00-10357
The Formosan subterranean termite, Coptotermes formosanus, is a serious pest in several parts of the world and is the most destructive insect in Louisiana. The density of the Formosan subterranean termite in the French Quarter, New Orleans, Louisiana, USA is very high. A large area pilot test for area wide management of this insect was begun in 1998 in the French Quarter to reduce densities of termites and demonstrate the effectiveness of the approach of treating all properties in a large area using area wide management. The pilot test is a cooperative effort between the LSU Agricultural Center, USDA-Agricultural Research Service and New Orleans Mosquito and Termite Control Board. All but four of 323 properties in a contiguous 15 block area in the French Quarter were treated using commercially available baits or non repellent termiticides selected by property owners and applied by professional pest control operators. Properties were inspected for conducive conditions and proper treatment after treatments were made. Data on termite activity were collected using glue boards for alates and in ground monitors for foraging activity. Alates were sampled two to three times weekly during the flight season (May through July 15) in both 1998 and 1999 using glue boards hung near lamps on street lights. Monthly monitoring of foraging activity began in January, 1999 to determine the number of stations with termites and amount of wood consumed. Reductions in densities of alates between years were not found; probably as a result of the limited time treatments had been in place. The percentage of in ground monitoring stations with termites was lower in the treated zone than outside the treated zone after September 1999. Continued treatment and monitoring are required to determine the extent of and the long term effects of the area wide management program.
D R Ring, A L Morgan, W D Woodson, A R Lax, X P Hu, E D Freytag, L Mao


Vapour boron treatment of wood based panels: Mechanism for effect upon impact resistance
1994 - IRG/WP 94-40036
Samples of medium density fibreboard, chipboard and oriented strandboard (OSB) were treated to two retentions of boric acid by a vapour phase treatment. The results of a range of mechanical tests were reported by Hashim et al. (1992, 1993) in which a small reduction in impact resistance was observed. Several investigations were carried out to study how and where this loss in impact resistance occured. Possible mechanisms for the loss in impact resistance are discussed.
R Hashim, R J Murphy, D J Dickinson, J Dinwoodie


Durability of surface preserved wood particle boards submitted to atmospherical influence
1995 - IRG/WP 95-40039
The worldwide problem of the continuously growing deficit of high quality natural wood material has caused the attempts of many research workers to find effective composites such as wood particle boards (WPBs) for replacing the massive wood for constructive purposes, depending on where the boards are exploited - in the open or under a shed, they are submitted to various climatic factors such as heating, drying, moistening, frosting, irradiation, that's why for reaching high atmospheric resistance, it is very important, a durable protection of the WPBs with suitable coatings against the atmospheric influence to be ensured.
L Valcheva


Worldwide in-ground stake test of acetylated composite boards
1997 - IRG/WP 97-40088
Acetylated wood composite stakes are being tested in ground contact (graveyard test) in seven fields around the world. Three types of acetylated wood composites were prepared: spruce fiberboard in Sweden, aspen fiberboard in Madison and rubber wood particle board in Indonesia. Two levels of acetylation were used, a high level of ~20% acetyl content and a low level of 10% acetyl content. Control boards of unmodified wood fiber/particle were also included. Stakes for the in-ground testing were taken from the boards and the size of each stake was 5x30x1.25 cm3. The stakes were put out in four continents: one test field in USA, one in New Zealand, two in Indonesia and three in Sweden. After three years of testing, results show that acetylation of wood provides excellent protection against fungal attack and minimizes swelling.
R M Rowell, B S Dawson, Y S Hadi, D D Nicholas, T Nilsson, D V Plackett, R Simonson, M Westin


Field trials of Sinesto B at some sawmills in Portugal
1989 - IRG/WP 3512
The efficacy of SINESTO B as antistain chemical for use in Portugal has been studied. The studies were done during the years 1987-1988 at several Portuguese sawmills in co-operation with the Instituto dos Produtos Florestais and the APCIM (Associacao Portuguesa de Comercio e Industria de Madeiras). SINESTO B was used in 5% and 8% concentrations. The storage time varied from 10 weeks to 6 months. In the tests, PCP was used as reference chemical as well as some other commercial antistain products. SINESTO B performed well in most of the tests. It was even better than 3% PCP. 8% concentration is recommended.
I A Linderborg


Evaluating the resistance of wood-based panel products to fungal attack
1995 - IRG/WP 95-20071
At present there is considerable disagreement among national research institutes within Europe and panel product manufacturers on the most appropriate method of testing and indeed the need for specific biological durability testing. This paper seeks to place before a broader international audience, the issues related to development of a European standard for evaluating the resistance to fungal decay of wood-based panel products. It rehearses the particular issues which need to be addressed. In particular it identifies as problems to be resolved, pre-conditioning of test samples to remove transient leachable/volatile preservative components, choice of weight loss or strength loss as efficacy criteria, and appropriate sampling levels.
R G Lea, R W Berry


Resistance to decay of particle boards: Presentation of a test method
1986 - IRG/WP 2260
The experimentations were undertaken on particle boards 35 and 50 mm thick. The rot resistance tests were carried out on specimens whose dimensions were 600 x 75 x 35 mm³ for particle boards 35 mm thick and 800 x 75 x 50 mm³ for particle boards 50 mm thick according to a method derived from the one described in the documents IRG/WP/2214 and IRG/WP/2243. Two exposure periods were used: 12 and 16 weeks. After exposure to the fungi, the extent of the attack on the specimens was measured by a static bending test according to the french standard NF B 51.224. The tests showed that if a 12 week exposure period to the fungi leading to losses of static bending resistance of 20 to 60% (depending on the fungi used) proved to be adequate for 35 mm thick particle boards, an exposure time of 16 weeks was necessary for particle boards 50 mm thick (losses of static bending resistance varied from 40 to 70% according to the strains of fungi used).
G R Y Déon, N Trong


European standardization for wood preservation. Progress report 91-92
1992 - IRG/WP 92-2398
Since the IRG 22 conference in Kyoto, CEN/TC 38 Plenary met twice in relation with several working group meetings. 5 upon 6 of the interpretative documents have been prepared by adhoc groups of the Standing Committee for Construction within the scope of the 89/106/EEC directive on Construction Products. The expected requirements attached to wood preservation are both requirements 1) and 3): 1) mechanical resistance and stability; 3) hygiene, health and the environment. A consequence should be a redrafting of the previous official mandate delivered on September 27, 1989: - direct mandate on wood (solid and reconstituted) as well as wood preservatives as construction products - horizontal joint-mandates on wooden-commodities in relation with the other TCs in charge of such commodities. Another consequence is a formal exploration by TC 38/WG 11 "Permanence of active ingredients in treated timber" through a first couple of standards entitled "methods for measuring losses of active ingredients and other preservative ingredients from treated timber - Part 1: Laboratory method for measuring losses by evaporation to air - Part 2: Laboratory method for measuring losses into fresh water or salt water". This works anticipates the mandate and means that TC 38 is currently making progress, towards air and water quality. Apart from building activities, TC 38 got also by the end of 1991 an order of standardization on Creosote, and Creosoted-timber following the 13th adaptation of 76/169/EEC Diretive Creosote specifications. This additional event results from the trend in Brussels to develop the so-called "new approach" where the EC authorities elaborates essential requirements with mandates to CEN explicit them in close cooperation with the industry.
R Hüe


Study on leaching of a magnesium fluorosilicate product (SF salt) from wood-boards by rain in the open and by artificial shower
1976 - IRG/WP 264
The test was performed in 1961 to obtain information about (1) the comparative leaching effect of natural rain and of artificial shower in the laboratory; (2) the comparative leaching effect on the active ingredient in proportion to the dye-stuff of the product. The results show that a continuos light rainfall with low precipitation has a much stronger leaching effect than short heavy showers with high precipitation. Thus the time of moistening with water flowing on the wood surface is the most decisive factor. The salt is not only washed off by rain but also transferred into the wood. This explains the relative resistance to leaching of a varying amount of salt with longer periods of exposure. The dye-stuff used fades away by leaching and light. much faster than the active ingredient.
S Cymorek


Factors affecting the resistance of fibre building boards to fungal attack
1975 - IRG/WP 252
Fungal decay is initiated at lower moisture contents in standard and tempered hardboards (18%) than in pine sapwood (26%). In contrast, in a saturated atmosphere, the equilibrium moisture contents of standard hardboard (14%) and of tempered hardboard (12.5%) are much lower than the moisture content permitting decay initiation whilst the equilibrium moisture content of pine sapwood (25.1%) approaches its decay initiation level. When immersed in water the hardboard, especially when tempered, took much longer to wet to decay initiation moisture contents than the pine sapwood but, on the other hand, the hardboards dried at much the same rate as the solid wood. It is concluded that the physical changes which occur during hardboard manufacture are such that under fluctuating service conditions, even when liquid water is intermittently present, hardboards tend to remain at risk from fungal attack to a much lesser extent than solid wood.
C Grant, J G Savory


Leaching of the copper component from full scale decking boards during one summer season
2009 - IRG/WP 09-50260
The leaching of copper has been tested in laboratory and in outside exposure for freshly treated pine sapwood samples with three different copper preservatives, Cu HDO, copper quat and copper triazoles. We found in the laboratory leaching test that a fixation with warming to 60 °C (140 °F) for 48 hours without drying and then drying in the laboratory in room temperature gave the lowest leaching of copper. We also found that surface treatments with wood oils reduced the leaching, and that washing of the surface before testing had no effect. Full scale decking board samples (0.25 m2) were then exposed outdoors for rain. The rain water was collected and analysed for copper. After one summer season (about 600 mm rain) we found that the leaching differ for the three preservatives. All samples with a water borne surface treatment had the lowest leaching, about half the amount of untreated.
F G Evans


Barefoot-heat-impact of oil-heat-treated wood: An important thermal property of decking boards
2009 - IRG/WP 09-40458
In this study the phenomenon of sensual heat impression was examined, when walking with bare feet on sun exposed wood based decking boards. A suitable method for measuring the heat flux from decking boards into an artificial foot was developed. The method and measuring device is described as well as results from measuring three different decking board materials: Oil-heat-treated spruce (OHT), untreated Bangkirai, and solid Wood Polymer Compound (WPC). The spruce OHT decking boards showed the lowest surface temperature after exposure to light (OHT 67°C, Bangkirai 76°C, WPC 85°C) and also caused the lowest temperature in the artificial foot (OHT 39.8 °C; Bangkirai 47.5 °C; WPC 52.3 °C). The measured heat flow density of the OHT decking boards was the lowest; the heat flow density of Bangkirai was three times and of WPC four times higher. The data obtained mirrored well the subjective sensation when walking on the three different materials with bare feet. After exposure to artificial solar radiation the OHT-spruce decking caused a feeling, which can be described as “conveniently warm”, whereas Bangkirai and in particular the solid WPC caused pain to the bare skin.
A O Rapp, C R Welzbacher, C Brischke


Effect of 4 Preservatives on Physical, Mechanical and Mold-Resistant Properties of Bamboo Oriented Strand Boards
2010 - IRG/WP 10-40483
This study investigated the effects of 4 preservative systems on physical, mechanical and mold-resistant properties of bamboo oriented strand board (OSB) panels bonded with urea formaldehyde resin. Preservative A (Zinc Borate), B (IPBC), C (AAC+Borate) and D (carbendazim + prochloraz) were incorporated with strands during blending at three loading levels. The results showed that the mechanical and physical properties of bamboo OSB experimental panels met the requirements for OSB/2 specified in the China Industrial Standard LY/T 1580-2000, with the exception of 24-hour water soaking thickness swelling properties of panels containing preservative C. The panels containing preservative A had the most excellent physical and mechanical properties while those containing preservative C presented the lowest quality, which indicated that addition of preservative C did have detrimental effects on the quality of panels. Of the 4 preservative systems, preservative B(IPBC) was proven to be the most promising as it fully inhibited the mycelia growth of the 3 experimental molds at the loading level of 0.5% and still provided the OSB panels with satisfactory physical and mechanical properties. Preservative A (Zinc Borate) and Preservative C (AAC+Borate) were tested to be only effective against the growth of Trichoderma lignorum at their corresponding highest loading levels, while preservative D showed no protection against the molds within the limit of this study.
Juwan Jin, Daochun Qin, Wanshu Wei, Kuan Fan


Copper distribution in soil leached from full scale decking boards during one year
2010 - IRG/WP 10-50265
The distribution of copper in the soil under exposed decking boards after one year has been analysed. The decking boards were impregnated with copper HDO, copper quat and copper triazoles. The decking boards were pine sapwood and pressure treated in a full cell process, fixed by heating and then dried. The samples were not surface treated. Each decking sample of five boards (0.25 m2) was placed on a frame of untreated spruce, 10 cm above the soil surface. In addition to the three treated samples, there was one untreated as a reference. After one year of exposure, the samples were removed and soil samples in different depths were taken. These were later boiled in de-ionised water and nitric acid (pH=2). The solutions were analysed for copper. Only the surface samples (0-2 cm) had elevated copper content compared to the back ground level. The copper fixes hard to the soil and only small amounts of copper will be washed out by rain.
F G Evans


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