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Influence of different fixation and ageing procedures on the leaching behaviour of copper from selected wood preservatives in laboratory trials
2003 - IRG/WP 03-20264
The paper focuses on the role of different parameters, such as fixation, sample size, wood species, and leaching in internationally standardized ageing procedures for wood preservatives from Europe, Japan and the United States. The leaching protocols used were EN 84, JIS K 1571 and AWPA E11 protocols. The wood species were Scots pine, Sugi and Southern Yellow Pine respectively. Three types of commercially important copper-based wood preservatives were used as model formulations, namely copper/copper-HDO, ammoniacal copper/quat and CCA. The most important factors determining the extent of copper leaching in the different lab trials were the sample size (volume/surface ratio) and the fixation conditions prior to leaching. On the other hand, the wood species and the leaching protocol itself were found to have only minor influence on the copper leaching rate in the test methods included in this study.
J Habicht, D Häntzschel, J Wittenzellner

Xenon simulation of natural weathering of external joinery preserving - Finishing systems
1992 - IRG/WP 92-2412
Semitransparent wood stains ('lazures') for external joinery have developed by means of product combination towards complete wood finishing systems that are easy to applicate, have a good weathering resistance and low maintenance cost. The search for enhanced formulations and the possibilities to standardize these products or treatment systems are always facing long periods of weathering tests. Extensive research was conducted to compare natural weathering with artificial ageing, using a scheme based on two cycle units commonly used for artificial weathering and intermediate low temperature exposures. Statistical analysis of test results showed good similarity between both natural weathering and Xenon ageing
J Van Acker, M Stevens, M Nys

Durability of plywood made from soft- and hardwoods assessed according to ENV 12038 after artificial and natural ageing
2000 - IRG/WP 00-20191
Plywood was prepared from Norway Spruce and pure heartwood of Douglas Fir, Scots Pine, European Oak, False Acacia and Macoré using a phenol-formaldehyde glue. The panels of 38 mm in thickness were pre-conditioned according to the following procedures: a) 12 weeks storage at 20°C/65% rh, b) 2 weeks artificial weathering (with rain and UV-radiation at changing temperatures), and c) a natural weathering according to ENV 12037 for 3 month, 6 month and for 9 month whereby the ENV 12038 specimens were cut from the lap-joints. In general for softwood panels the decay was lowest after a 12 weeks` storage and the artificial weathering increased the decay rate more than the natural weathering applied. For False Acacia the durability was gained as predicted by EN 350-2 but not for the other species. Especially for European Oak and Macoré the durability was much lower than expected. Further, it has to be mentioned that the specimens usually showed a more intensive attack close to the nutrient media than at the top of the specimens. This indicates that the laboratory results might be influenced by the thickness of the panel tested because thinner material would be more equally degraded and thus would show a lower grade of durability.
H Leithoff, R-D Peek

Laboratory tests on artificial weathering of Quercus rubra crossties
1986 - IRG/WP 2252
Clear red oak (Quercus rubra) blocks were used to evaluate various types of accelerated aging tests including boil, steaming, and cyclic weathering. It was found that the repeated vacuum and pressure treatment of wood in water, steaming, oven-dry, and freezing appeared to be most effective in reducing the MOE in compression and hardness modules of wood specimens. Red oak crossties which were pressure treated with creosote - coal tar preservative were tested using the cyclic aging technique. This method will be used to establish correlation between short-term accelerated aging test results and long-term in service performance of wood crossties.
P Chow, A J Reinschmidt, E J Barenberg, S L Lewis

Artificial weathering exposure as an alternative for standard ageing according to EN 84 (leaching) and EN 73 (evaporation)
2002 - IRG/WP 02-20254
In order to verify potential weaknesses of wood preservatives fungal tests are carried out after ageing of wood preservative treated test blocks. The European standard EN 599 as a framework for efficacy assessment of wood preservatives includes the use of two ageing methods prior to fungal testing, namely a leaching method (EN 84) and an evaporation method (EN 73). The European research project "F.A.C.T." aimed amongst other objectives to provide in more realistic alternatives for both ageing methods. Artificial weathering systems generally used to assess the weathering resistance of exterior coatings was looked at as an alternative. For this purpose artificial weathering devices were selected which besides a control of temperature and light also allow for the impact of moisture by means of water spraying. UV cabinets with spray option were used to evaluate the effect of ageing of three wood preservatives: a waterborne Cu-HDO preservative, an oilborne triazole combination and a TBTO reference preservative. Based on EN 113 Basidiomycete testing of aged specimens a range of equivalent UVS systems proved to be suitable as an alternative ageing system prior to EN 84 and EN 73.
J Van Acker, M Grinda, D J Dickinson

Accelerated weathering test for the evaluation of wood preservative efficacy
2003 - IRG/WP 03-20262
Wood samples treated with ammonium copper quat (ACQ-1900 and ACQ-2200), Chromated copper arsenate (CCA), Tanalith E 3491 and Wolmanit CX-8 have been studied in accelerated weathering experiments. The weathering experiment was performed by cycles of 2 hours UV-light irradiation followed by water spray for 18 minutes. The changes on the surface of the weathered samples were characterized by FTIR Spectroscopy and color measurements on the samples with 0, 200, 400 and 600 hours of total weathering. The objective of this study was to investigate the changes created by weathering on impregnated wood with several different wood preservatives. This was performed study, accelerated weathering using UV irradiation and water spray was used to simulate natural weathering. FTIR and color measurement was used to investigate the changes after several intervals (0- 200 h- 400 h- 600 h) in artificial weathering of treated and untreated wood.
A Temiz, M Eikenes, Ü C Yildiz, F G Evans, B Jacobsen

Comparative study of blue stain resistance of various types of wood stains after artificial and natural weathering
1992 - IRG/WP 92-2411
For the determination of the protective effectiveness of a preservative treatment against blue stain in service, artificial weathering has been proposed as an alternative for the natural weathering period of 6 months in the European standard EN 152. Research on a range of products and on complete finishing systems for external joinery was conducted during 1986-1990. It revealed that the decisions drawn after 4 weeks Xenontest do not always confirm those of the EN 152 natural weathering test. Results were influenced by the nature of the formulation, the resin binder and the product combination (treatment system). However the variation among the ageing methods generally does not effect the practical conclusions on the blue stain resistance when well-defined limits are considered.
J Van Acker, M Stevens, M Nys

Alkyl dimethyl benzyl ammonium chloride: toxicity to Coniophora puteana when formulated in water and organic solvent
1986 - IRG/WP 2250
Results from agar block tests using Coniophora puteana demonstrate that the biological activity of alkyl dimethyl benzyl ammonium chloride is affected by the nature of the carrier solvent in which it is applied. In contrast to some earlier work, an alkyl ammonium compound in organic solvent formulation was identified that had significantly greater activity than its aqueous equivalent. A simple solution of alkyl dimethyl benzyl ammonium chloride in xylene did not exhibit increased activity relative to that of the same alkyl ammonium compound in aqueous solution. The reasons for the differences in performance cannot at present be fully explained.
D P Blow

Proposal for further work on accelerated ageing
1988 - IRG/WP 2314
M-L Edlund

Studies on accelerated ageing procedures with TBTO-treated wood
1985 - IRG/WP 2244
The efficacy of various procedures for accelerated ageing of organotin based wood preservatives in treated wood has been investigated. It was found that leaching of the treated wood samples in water according to the European Standard EN 84 was not satisfactory for organotin based preservatives and is probably also unsuitable even for other types of organic solvent preservatives. Keeping tributyltin oxide (TBTO) treated samples in a heating cabinet at 70°C for five weeks, however, had a considerable effect on the breakdown of TBTO and the subsequent decay test. Therefore, an ageing procedure involving a heating period should be considered for all organic solvent wood preservatives. The investigation also confirmed that elevated temperatures accelerate the degradation of TBTO and that there is a strong correlation between the percentage of TBTO in the wood and its resistance against decay.
J Jermer, M-L Edlund, B Henningsson, W Hintze

Report on the activities of the European Standardization Committee CEN/TC 38 'Methods of Testing wood preservatives'
1980 - IRG/WP 279 E
G Castan

Fungicidal combination products
1987 - IRG/WP 3426
Due to the increased pressure on some of the established fungicides used in wood preservation, possible alternative products become more interesting. The requirements for new chemicals are mainly lower toxicity and greater environmental acceptability. However the efficacy to target organisms should be as good as that of the currently used ones, preferably better. A possibility for progress in this direction could be fungicidal combination products showing broader spectrum of efficacy and synergistic effects. Mixtures of tributyltin compounds with Furmecyclox and K-HDO respectively are tested for this purpose. Toxic values with and without artificial ageing (wind-tunnel exposure and leaching) were determined. Investigations have been made with coating-formulations in order to test penetration, evaporation and the influence of UV-radiation. Aqueous formulations were tested for special purposes such as the treatment of freshly cut timber and the protection of brickwork. The results obtained are very promising, especially regarding long term durability. Further investigations mainly with the aqueous formulations including other test fungi and field trials are necessary to confirm the suggested application as wood preservatives.
H A B Landsiedel

Field tests out of ground contact in France: Definition of the test procedure and preliminary results after 18 months
1981 - IRG/WP 2161
M Fougerousse

Rapport sur l'activité du CNE/TC 38 'Méthodes d'essais des produits de préservation du bois'
1980 - IRG/WP 279
G Castan

Blue stain in timber in service. Results of co-operative tests to compare different artificial weathering systems 1981-82
1983 - IRG/WP 2193
The paper describes results of the third phase of co-operative laboratory experiments comparing the effects of different artificial weathering systems on chemicals to control blue-stain in service. Atlas, Xenotest and Marr equipments are shown to give essentially the same results for 5 of the 6 chemicals tested.
A F Bravery, D J Dickinson

Preventive action against fungal decay: A comparative experiment on the effects of natural and artificial infection of wood by Basidiomycetes
1981 - IRG/WP 2160
M Fougerousse

A comparison of the effectiveness of a vacuum oven and a wind tunnel in the accelerated ageing of treated wood by evaporation
1989 - IRG/WP 2334
R J Orsler, G E Holland

Accelerated ageing of preservatives in treated wood
1988 - IRG/WP 3476
New preservatives are tested in the laboratory and often in field tests before they are used commercially. Some preservatives, however, tested in the laboratory do not show the expected stability when used in service. The differences between laboratory tests and practical use can never be completely eliminated but must be minimized as far as possible by relevant testing methods. Studies of the effect of different accelerated ageing procedures on the chemical degradation and the wood preserving capacity of six different fungicides or combinations thereof have been carried out. Chemicals tested were tributyltinoxide (TBTO), tributyltin naphthenate (TBTN), furmecyclox, benzalkoniumchloride (AAC) + guazatin and pentachlorophenol. The ageing procedures included exposure of test specimens in a wind tunnel (according to EN 73), in an oven at 40°C, 60°C and 70°C, leaching (according to EN 84) and combinations of these procedures. The influence of the different accelerated ageing procedures on the chemical degradation and toxic effect of different fungicides was obvious and, for some procedures and chemicals, comparable with experiences from practice.
M-L Edlund, B Henningsson, B Jensen, C-E Sundman

A comparison between methods for evaluating the water repellency of wood
1989 - IRG/WP 2328
Wood specimens treated with a number of water repellent formulations have been tested for their water repellency according to four laboratory test methods, based on weight increase, swelling and contact angle measurements, in order to assess the degree of agreement between the different methods. Treatments representing formulations with a wide range of water repellent efficiency were tested both initially and after simulated weathering. A ranking of the water repellent treatments shows deviations between the different test methods although the general agreement is relatively good. Contact angle measurements are less appropriate due to a poor repeatability. The development of new standard test methods where the long-term performance or water repellent treated wood is evaluated by a weathering procedure is of great importance.
R Nussbaum

Electronic noses for detection of rot in wood
1996 - IRG/WP 96-20098
In an ongoing project an electronic nose is being studied and developed for detection of volatile organic compounds (VOC) emitted from wood colonised and decayed by fungi. The electronic nose consists of an array of gas sensors with different selectivity patterns for different groups of volatile organic compounds (VOC). The use of pattern recognition routines implemented by artificial neural networks (ANN) is used to evaluate data from the sensor array. The responses from the sensor array have been correlated to weight loss of and contents of chitin in the decayed wood samples. The results obtained so far indicate that the electronic nose qualitatively can detect significant differences between sound and decayed sapwood of Scots pine (Pinus sylvestris). Preliminary results also indicate that the electronic nose can detect differences between decay types like brown rot (Lentinus lepideus) and soft rot (Phialophora A). Results from a study aiming at investigating the abilities of the electronic nose to quantitatively detect different stages of decay is now being analysed statistically. The influence on the responses from the sensor array due to variation in relative humidity, moisture content of the decayed wood samples and temperature have also been studied.
K Nilsson

Artificial drying of impregnated wood
1987 - IRG/WP 3448
Sawn timber (Pinus Sylvestris) of dimension 50x150 mm was impregnated with CCA by a full-cell process. The timber was then dried in a conventional kiln or a special vacuum kiln where the timber was dried by circulating superheated steam. Drying time was 16 days and 2 days respectively. The aim of the investigation was to compare the physical appearence of the wood after drying by the two methods with particular reference to formation of checks. Moisture contents and checks were therefore recorded before and after drying. It was found that the number of checks formed was approximately the same by either drying system and no inner checks were found. The drying in superheated steam, however, caused bleeding of resin on the surface of the wood, which could be a disadvantage for some end uses.
M-L Edlund

Testing wood in ground contact: An artificial soil
1977 - IRG/WP 280
This document is an interim report on the development of the artificial soil medium. It includes some information on the relationship between soil, wood and water which is of relevance in testing.
E F Baines, D J Dickinson, J F Levy

Checking of sodium pentachlorophenate fixation in wood
1990 - IRG/WP 3620
In order to estimate the volatilization of sodium pentachlorophenate from treated wood, wood samples treated with pentachlorophenate were analysed after various durations of an EN 73 weathering The results giving no clear evidence of volatilization, treated wood samples were put in a test chamber with precise climatic conditions, the air used in the experiment being analysed. The pentachlorophenate content in air was quantified: 1.8 µg/m³
M Lamour, H Sageot

The potential for accelerated ageing to determine the persistence of active ingredients in timber
2006 - IRG/WP 06-20323
Fast screening methods for evaluating the persistence of active ingredients in timber are proposed. This is an outline proposal which is intended to provoke discussion and further development of the methods. Reliable and accurate analytical methods are key to these tests.
L D A Saunders, M R Powell

Effects of artificial UV weathering and soft rot decay on heat treated wood
2005 - IRG/WP 05-40302
Oil and inert gas oven heat treated pine wood strips 100 µm thick were mildly heat treated (200°C, 30 mins linseed oil, 120 mins oven). Following treatment, specimens were exposed to UV weathering (300 hours) and decay by the soft rot fungus, Chaetomium globosum. The effects of each treatment were assessed by zero span tensile testing, microscopy and by FTIR. Tensile testing of heat treated strips showed greater strength losses in the oil treated samples (73%) than in the oven treated samples (26% loss). Heat treatment darkened the wood strips but this was photo-bleached on exposure to UV artificial weathering. The UV exposure caused some loss in tensile strength (35%) but the additional effects of UV on the tensile strength were less in heat treated wood (oil 15%, oven 18%). The combined effects of UV and fungi on the tensile strengths were less severe for treated wood than in untreated wood, (oil 4%, oven 18%) thus some protection was afforded by the heat tretaments. Exposure of untreated wood strips to the soft rot fungus caused some loss in tensile strength (32%), but heat treated wood showed small but not statistically significant gains in tensile strength after fungal exposure (oil, gain 30%, oven, gain 3%). Microscopic examination confirmed that a soft rot was minimal in heat treated samples, i.e. it was mainly confined to wood cell wall penetration. The combined effects of UV and fungi caused further losses of tensile strength in both oven and oil heat treated samples, but this loss was less severe than that which occurred in untreated controls. However, due to the severity of the initial losses caused by the oil heat treatment, the highest losses overall were in those oil heat treated samples exposed to UV (82%) and UV and decay (78%). Microscopic examination revealed that decay was more advanced in UV exposed samples. The FTIR spectra of oven heat treated samples did not show any change, while the oil heat treated samples increased absorbance at 1737cm-1 and 1450cm-1 relating to the presence of oil. Following fungal decay, no changes were observed, this corresponds with the cavity attack by soft rot fungi, which leave adjacent portions of cell wall material untouched. The ultra violet exposure affected the spectra of all specimens, increasing the absorbance at 1737cm-1. This relates to photo-degradation of the hemicelluloses, forming new carbonyl groups. In the UV exposed untreated wood there were also increases in absorbance at 1510 and 1160cm-1 relating to alterations in lignin structure.
M D C Hale, S C Ghosh, M J Spear

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