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A practical method to evaluate the dimensional stability of wood and wood products
1990 - IRG/WP 2342
This paper presents a new simple method to evaluate wood and wood products for their resistance to swelling and to assess wood preservatives for their ability to dimensionally stabilize treated wood exposed to water. Permeable wood of various dimensions and treated with different preserving chemicals have been measured for swelling in the radial and tangential direction during immersion in liquid water. The results indicate that a simple exponential function describing the dimension of the samples during immersion can be used to evaluate both the water-repellency and anti-swelling effectiveness of wood preserving chemicals. The results can be achieved in reasonable time, and the parameters of the function can be determined by a commercial desk-top computer program.
J P Hösli


Effects of heat treatment on water repellence and anti-swelling efficiency of beech wood
2002 - IRG/WP 02-40223
The heating of solid wood to higher temperatures is the simplest and the cheapest means for stabilizing its dimensions. For the investigation of the effect of thermal treatment on water repellency effectiveness and anti-swelling efficiency of beech wood (Fagus orientalis Lipsky), air-seasoned samples of beech wood were heated in presence of air at temperatures of 130 C, 150 C, 180 C and 200 C for different periods (2, 6, 10 h). Subsequently, the heated samples and their controls were immersed in water at 20 C, 65 % relative humidity for various periods. Percent of the tangential swelling and rate of the water absorption values of the test and control samples were determined for 2, 4, 8, 24, 48, 72 h on basis of oven-dried measurements. The heat treatment brought about a considerable reduction in water absorption and tangential swelling of the beech wood.
S Yildiz


Investigation of the suitability of silver fir (Abies alba Mill.) for thermal modification
2004 - IRG/WP 04-40275
In this study the suitability of silver fir (Abies alba Mill.) was examined for thermal modification. Comparative experimental investigations were performed with silver fir and Norway spruce (Picea abies Karst.) after thermal treatments. Besides properties, which characterize the quality of heat treatments, like dimensional stability and resistance against fungal attack, strength properties of the heat treated material were tested, i.e. bending strength, modulus of elasticity (MOE), impact bending strength and resistance to abrasion. Silver fir was found to be slightly more suitable for thermal modification than spruce, when treated at 180 °C, whereas thermal modification at 220°C showed a comparable suitability for both species. Advantages of silver fir were found for its impact bending strength, durability, and formation of cracks after weathering.
C Brischke, A O Rapp


Influences of the hydro-thermal treatment on physical properties of beech wood (Fagus orientalis)
2005 - IRG/WP 05-40303
Influences of the hydro-thermal treatment on physical properties of beech wood were studied. Wood specimens (2×2×2cm) were treated in two steps. At first step, samples were treated at 160,180 & 200ºC for 4, 5 & 6 hours. At second step, treated samples were cured based on their first step treatment temperatures (160,180 & 200ºC) for 16 hours. The treated samples were soaked in water and oven dried for 24 hours. The soaking-drying cycles were repeated for seven times. Oven dried density (initial and final), swelling (initial and final), water absorption (initial and final) and density loss were analyzed. Results revealed that swelling was decreased due to the hydro-thermal treatment; while the water absorption was increased in wood. And oven dried density was slightly lost due to the treatment. The density loss and increase of water absorption are related to initial pyrolysis of wood which consequences with increase of wood porosity due to the treatment.
B Mohebby, I Sanaei


Evaluation of Water Repellency of Treated Wood Using Several Alternative Methods
2009 - IRG/WP 09-20419
In this study, the results of water repellency testing using a digital swellometer method for water-borne organic-preservative systems with water repellent additives are reported. The findings suggest that the traditional method of using matched untreated controls as a reference developed from historic solvent-based treatments for determination anti-swelling efficacy (ASE) may underestimate the actual effectiveness of a given water repellent (WR) system in water-borne treatments. The results show that using a water-treated control may provide a more accurate measurement of the water repellency with any given water repellent additive system for water-borne preservatives. The potential of using data generated from digital swellometer testing are also discussed. These outcomes include water resistance performance monitoring for commercial products, providing indications of the system differentiation in terms of formulation chemistries and their subsequent influence on the water repellency, developing practical guidance and prediction of performance for the WR use-level based on the intended applications, and using characteristics of the swelling curves to estimate important information regarding any dimensional stability imparted by the treatments.
L Jin, A F Preston


Relationships between heat treatment intensity and some conferred properties of different European softwood and hardwood species
2012 - IRG/WP 12-40593
Effect of treatment intensity on conferred properties like elemental composition, durability, anti swelling efficiency (ASE) and equilibrium moisture content (EMC) of different European softwood and hardwood species subjected to mild pyrolysis at 230°C under nitrogen for different durations has been investigated. Independently of the wood species studied, elemental composition is strongly correlated with the mass losses due to thermal degradations which are directly connected to treatment intensity (duration). In all cases, an important increase of the carbon content associated with a decrease of the oxygen content was observed. Heat treated specimens were exposed to several brown rot fungi and the weight losses due to fungal degradation determined after 16 weeks, while effect of wood extractives before and after thermal treatment was investigated on mycelium growth. ASE and EMC were also evaluated. Results indicated important correlations between treatment intensity and all of the wood conferred properties like its elemental composition, durability, ASE or EMC. These results clearly indicated that chemical modifications of wood cell wall polymers are directly responsible for wood decay durability improvement, but also for its improved dimensional stability as well as its reduced capability for water adsorption. All these modifications of wood properties appeared simultaneously and progressively with the increase of treatment intensity depending from treatment duration. At the same time, effect of extractives generated during thermal treatment on Poria placenta growth indicated that these latter ones have no beneficial effect on wood durability.
M Chaouch, S Dumarçay, A Pétrissans, M Pétrissans, P Gérardin


Effects of nano-wollastonite impregnation on fire resistance and dimensional stability of Poplar wood
2012 - IRG/WP 12-40595
The fire-retardant properties of Nano-Wollastonite (NW) in poplar wood (Populus nigra) were determined in this study. Some physical properties such as water absorption, volumetric swelling and Anti-Swelling Efficiency (ASE) were also measured. Specimens were prepared according to the ISO 11925 standard for the fire-retarding properties, and ASTM D4446-2002 standard for the physical properties. Impregnation of wood specimens with nano-wollastonite was carried out using the Ruping Method (empty-cell process) with a concentration of 10%. Three fire-retarding properties were measured; weight loss, ignition point and fire endurance. The results showed that fire-retarding properties increased in the NW-treated specimens. In addition, the NW-impregnated specimens gained higher dimensional stability. However, the water absorption also increased.
A Karimi, A Haghighi Poshtir, H Reza Taghiyari, Y Hamzeh, A Akbar Enayati


Superhydrophobic treatment of Norway spruce wood for improvement of its resistance against brown rot and moulds
2016 - IRG/WP 16-40734
Water repellence of wood can be increased and its some other properties influenced by introduction of hydrophobic chemicals into and on cell walls without affecting the wood’s bulk density due to lumen filling. Herein, a simple dipping method to insert octadecyltrichlorosilane (OTS) into cell walls and to deposit the self-assembled hydrophobic monolayers (SAMs) of OTS is reported. It was found out that the treatment of Norway spruce wood with OTS caused superhydrophobicity of the specimens. At the same time, liquid water uptake was reduced, the equilibrium moisture content lowered and the dimensional stability in terms of the anti-swelling efficiency was increased. Hydrophobicity and lower equilibrium moisture content are believed to be the reason for the observed increased resistance of the treated samples against Coniophora puteana and moulds.
A Kumar, P Ryparová, P Hajek, B Kričej, M Pavlič, A S Škapin, M Šernek, J Tywoniak, J Žigon, M Petrič


Hydrolytic stabilization of chemically modified Bambusa vulgaris Shrad ex JC Wendl
2018 - IRG/WP 18-40830
The main drawback which greatly limit the utilisation of bamboos is their high moisture intake, biodegradation and physical properties changes with environmental variations. To prevent excessive dimensional changes and improve moisture properties of bamboo, Bambusa vulgaris was chemically treated with acetic-anhydride without co-solvent. To evaluate the influence of acetylation on the moisture properties. The weight gain (WPG), Bulking coefficient (BC), Rate of reaction (RR), Volumetric Swelling (VS) and Anti-swelling Efficiency as well as changes in VS and ASE upon long term water soaking and weight loss to leaching (WL) were determined. The results indicated no significant effect of reaction temperature and time on the WPG, BC, VS and ASE of the acetylated bamboo while reaction time had significant influence on RR and WL. None of the bamboo samples had more than 3.67% WPG and 54.69 % ASE. The maximum values of ASE of acetylated bamboo was 54.69% at 2.785 WPG while the lowest 13.08% was recorded at 2.89% WPG. However, at the lowest WPG of 1.61 %, ASE of 35.88% was recorded while the highest WPG of 3.67% gave ASE of 32.84 %. ASE varied from 13.08 % to 54.69% the lowest being recorded at 140oC, 30 mins reaction time while the highest (54.69%) was recorded at 100oC, 90 minutes reaction time. Temperature had no influence on the initial and final volumetric swelling and final anti-swelling efficiency of the modified bamboo samples but reaction time had significant effect on initial ASE. Volumetric swelling of modified samples increased from 8.47 to 18.58% while the unmodified samples swelled from 9.42% to 43.22% within 7 days water soaking period. Acetic anhydride form chemical bonds that are stable to solvent extraction in B. vulgaris. Acetylating at 120°C for 30 and 60 minutes is suitable for B. vulgaris to positively influence its sorption properties.
N A Sadiku, S M Akintayo


Water interactions in wood polyesterified with sorbitol and citric acid
2020 - IRG/WP 20-40888
Polyesterifcation of wood with sorbitol and citric acid seems to be a promising chemical wood modification technique that is both low-cost and produced from bio-based chemicals. An interesting aspect of the modification is the interaction of water with the polyesterified wood since the relationship with moisture appears to be unique compared to other wood modification systems. This communication paper presents preliminary results from trials assessing the effect of weight percentage gain (WPG) on swelling properties and water saturated low-field NMR (LFNMR) spectra. Bulking coefficients indicated that the sorbitol-citric acid polymer penetrated the cell wall and higher WPGs led to greater bulking coefficients. Surprisingly, anti-swelling efficiency decreased with increasing WPG. This was due to an increase in water saturated volume at high WPG which suggests the modification alters the structure of the cell wall in a way that allows it to swell beyond its original volume. LFNMR spectra showed the development of a new peak with increasing WPG which may be attributed to water associated with the hydrophilic sorbitol-citric acid polymer.
G Beck, A Treu, E Larnøy


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


Some textile auxiliaries as wood protective agents
2007 - IRG/WP 07-30417
This study evaluated some textile auxiliaries applicable for wood protection. Commercial alkoxysilane quarternary ammonium formulation and fluorocarbon based water-oil repellent were tested for their ability to provide hydrophobicity and antifungal effect to solid wood samples. Scots pine (Pinus sylvestris L.) sapwood samples were impregnated with 25, 50 and 100 % concentrations of the above mentioned compounds and cured in an oven at 80 ?C for 24 h. Water absorption rate (WAR), anti-shrink efficiency (ASE) and compression strength parallel to grain of the wood samples were determined. Biological resistance of leached and unleached wood samples against fungal decay was evaluated with a modified soil block test using Postia placenta. Fluorocarbon based water-oil repellent and alkoxysilane quarternary ammonium treated samples demonstrated some improved durability against decay fungi and anti-shrink efficiency compared to the untreated controls. The water uptake of treated wood was significantly reduced, especially after the treatment with alkoxysilane quarternary ammonium. The initial water repellence was well pronounced with the both tested chemicals, but after a longer submersion time (2 weeks), the reduction in water uptake was significantly diminished. No significant decrease of the compression strength parallel to grain of wood samples was monitored. Although the improved durability of wood treated with the tested formulations, the performance is far poorer than that of the commercially available copper-based formulations.
E Dizman, A Temiz, N Terziev, Ü C Yildiz


Improving dimensional stability of thermally treated wood by secondary modification – potential and limitations
2014 - IRG/WP 14-40664
The potential of treating thermally modified wood with melamine resin to improve the dimensional stabilization is tested in this research. Two different boards of poplar (Populus ssp.) were cut into two halves. One half of each board was thermally modified (T1 and T2) in a commercial process, the other half was used as untreated reference material. The material was thermally modified using the vacu³ process under vacuum and maximum temperatures of 210 °C and 230 °C. Ten samples of each material were impregnated with a solution of a commercially available methyloated melamine resin and dry-cured in a laboratory oven at a maximum temperature of 120°C. The anti-swell-efficiency (ASE) based on the swell rate was tested during ten cycles of repeated drying and wetting. The melamine treatment caused a higher bulking in the references than in thermally modified wood. The ASE of T1 was improved by secondary modification, whereas the ASE of T2 remained higher than that of the secondary modified material. The melamine treatment of thermally modified poplar yielded good results for solution uptake and weight percent gain, but the bulking was lower than expected. Reasons may be found in the same mechanisms providing good dimensional stability of thermally modified wood in the first place: The cell walls are more inaccessible for melamine oligomers due to hydrophobation resulting from thermal modification.
G Behr, K-C Mahnert, S Bollmus, H Militz


Effectiveness of "Gang-Nail" plates in preventing splitting of Eucalyptus poles and Brazilian hardwood sleepers
1984 - IRG/WP 3262
This paper presents the results of some tests carried out with an anti-splitting device, placed on the end surfaces of Eucalyptus spp utility poles and Brazilian hardwood sleepers at the beginning of an air-drying period. The type of device used, a "Gang-Nail" plate, reduces significantly the splits at the end-surface of poles, but reduces only a little the splits occurring in sleepers.
A M F Oliveira, J A C Sodré, O B Neto


In search of alternative antisapstain chemicals for use in Papua New Guinea
1988 - IRG/WP 3472
The paper presents results of antisapstain field trials from three locations in Papua New Guinea as part of the Research Centre's programme to find suitable antisapstains to replace the hazardous sodium pentachlorophenate. Effectiveness of seven tested chemicals varied between indigenous pines (Araucaria cunninghamii, Araucaria husteinii) and white coloured hardwoods (Alstonia scholaris, Pterocymbium beccarii) but not between sites. The indigenous pines required lower chemical concentration for same level and period of protection than white coloured hardwoods like amberoi and white cheesewood. Period of protection ranged from four weeks to a maximum of 16 weeks depending on chemical concentration and species of timber. Potential chemicals recommended for use as antisapstain include Celbrite T, Busan 1009, Penacide and Woodguard E.S. and Woodguard E.C.
A Oteng-Amoako


Observations on the colonization of freshly-felled timber treated with prophylactic chemicals by mould and sapstain fungi
1989 - IRG/WP 1394
Field tests using freshly felled pine sapwood were set up to determine the effectiveness of a range of antisapstain compounds and to study the problems of colonization by mould and sapstain fungi. Differences were recorded both in the overall performance of the compounds and also their selectivity in controlling specific fungal types. These results were found to be useful in gaining a better understanding of biocide - fungal interactions.
G R Williams, D A Lewis


Proposed standard laboratory method for testing fungicides for controlling sapstain and mould on unseasoned lumber
1977 - IRG/WP 292
This laboratory method is for determining the effective concentration, or concentration for zero growth (CGo), for fungicides or preparations of fungicides which are potentially useful in protecting packaged or unseasoned lumber in storage and shipment from biodeterioration by sapstain fungi and moulds. The test is rapid and may be completed in three weeks and gives a good indication of the toxicity of a chemical against sapstain fungi and moulds.
A J Cserjesi


Commercially available anti-sapstain chemicals in New Zealand - An update
1987 - IRG/WP 3416
Six anti-sapstain chemicals or mixtures (NaPCP plus borax, Haipen 5F, Mitrol PQ375, Busan 1009, Protek S, Pinefol 50W) are available as commercial treatments in New Zealand. A further two (Hylite 20F and Isothon-35) have shown potential in field and mill trials and will be available for use. A number of other formulations are under evaluation.
J A Drysdale


Nouvelles techniques de lutte anti-termites à faible impact environnemental
1995 - IRG/WP 95-50040-32
P Martinet


Mould resistance of lignocellulosic material treated with some protective chemicals
1984 - IRG/WP 3294
Effectiveness of preserving lignocellulosic material against moulding by treatement with water solutions of commercial wood preservatives and mixtures of various inorganic salts was investigated and compared with the effectivenes of sodium pentachlorophenoxide and boric acid.
K Lutomski


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


Selective adsorption of antisapstain actives from two aqueous suspensions, and movement of actives into wood
1996 - IRG/WP 96-30103
Green-off-saw rough sawn Pinus elliottii (slash pine) boards were dipped in aqueous suspensions of two antisapstain formulations, NeXgenâ and Busanâ Sap Stain Preventative (Busan 1009), at three product concentration levels. Concentrations of active ingredients (NeXgen: CTL (chloro-thalonil) and MTC (methylene bisthiocyanate); Busan 1009: TCMTB (2(thiocyanomethylthio)-benzothiazole) and MTC) were monitored with respect to the amount of material dipped. Selective adsorption (removal of actives from the suspension at greater than simple volumetric transfer rates) varied with formulation and active ingredient, and increased with decreasing product concentration. Movement of active ingredients into dipped boards was monitored for 30 days after dipping. Mobility order was MTC >> TCMTB > CTL. Surface depletion characteristics were obtained for each active ingredient.
M J Kennedy, T L Woods


The identification and preservative tolerance of species aggregates of Trichoderma isolated from freshly felled timber
1992 - IRG/WP 92-1553
The surface disfigurement of antisapstain treated timber by preservative-tolerant fungi remains a major problem in stored timber. Identification of a range of isolates of Trichoderma based on microscopic morphological characteristics was found to be imprecise due to the variable nature of this organism. In addition, studies to compare visual (morphological) characteristics of these isolates with their tolerance to the antisapstain compound methylene-bis-thiocyanate (MBT) using minimum inhibition concentration (MIC) tests showed no clear correlations. Isoenzyme electrophoresis was used to investigate the taxonomic relationships between species aggregates of Trichoderma isolated from antisapstain field trials and to identify physiological differences between 30 isolates of Trichoderma which show tolerance to MBT at concentrations ranging from less than 4 ppm to 34 ppm. Results indicate that there is considerable variability in the preservative tolerance of different Trichoderma isolates from particular locality. This highlights the need for field testing of an antisapstain compound in the same locality and under the same conditions in which it will be used in practice.
R J Wallace, R A Eaton, M A Carter, G R Williams


Observations on the failure of anti-sapstain treated timber under non-drying conditions
1990 - IRG/WP 1437
A range of bacteria and yeasts were isolated from antisapstain treated timber and fresh sawdust. Solution samples containing 100 ppm of TCMTB in a nutrient medium were inoculated with these organisms and incubated at 25°C for 5 days. The levels of TCMTB remaining in solution were determined by HPLC analysis after this time. Results indicated high losses of active ingredient for a range of organisms. These results suggest that active biodetoxification of organic biocides could occur in a short period of time during storage of antisapstain treated timber under favourable conditions. The implications of these results are discussed.
G R Williams


Austrian field test method for anti-sapstain chemicals
1994 - IRG/WP 94-20020
Although Austria is a small country, the annual consumption of anti-sapstain products ranks to approximately 500 tons annually. In 1994, only three products will be approved by the Austrian Wood Preservation Committee (AWPEC). There is demand for a field test method, which demonstrates the efficacy of an anti-sapstain product and consequently implies the acceptance and approval of product by the AWPEC. Present field test was carried out in 1992 and 1993. The results were evaluated after six months storage of test stacks. A TCMTB based product was used as a reference. The results show that the AFPRL method proves very suitable for the simulation of practical situation in Austrian treatment plants, where pine and/or spruce are treated periodically and where different methods of stack storage are applied.
R Gründlinger, M Brandstätter, H Melzer, O Janotta


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