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The use of ESR spectroscopy to assess the photostabilising effects of wood preservatives
2000 - IRG/WP 00-20186
The degradation of wood surfaces exposed to UV light which leads to poor performance of clear coatings is understood to be due to delignification via a mechanism involving free radicals. Certain wood preservatives most notably CCA are able to photostabilise wood and therefore they may reduce the concentration of free radicals formed when treated wood is exposed to ultraviolet light. As a first step to prove this hypothesis we have treated a number of thin Scots pine veneers with two different commonly used wood preservatives (CCA, ACQ) and two effective photostabilising treatments (HEBP, DHBP). Treated veneers were then placed in an ESR spectrometer which allowed the samples to be exposed to UV radiation while the spectra were recorded. The spectra were compared with that obtained using untreated wood. The results are very encouraging showing a smaller concentration of free radicals in preservative treated veneers than in untreated controls and there is also marked differences between the various treatments. More work is needed to establish a direct relationship between free radical concentration as measured by ESR spectroscopy and prolonged longevity of a wood surface exposed outdoors. Ultimately ESR spectroscopy has the potential to substitute time consuming and costly weathering trials, at least for screening of large numbers of unknown compounds for their ability to prevent the photodegradation of wood.
S Schmid, R D Webster, P D Evans

Experiments on the degradation of tributyltin oxide: A progress report
1984 - IRG/WP 3287
A variety of experiments designed to assess the chemical and physical factors affecting the degradation of tributyltin oxide in treated timber are described. Simple procedures in which temperature and oxygen availability were increased in the presence of wood and water suggest that the wood itself was of prime importance. Attempts to decrease degradation with antioxidants were unsuccessful but led to the idea that free radicals may be instrumental in the degradative mechanism. Subsequent work in which a range of antioxidants and free radical producing systems were used confirmed the susceptibility of tributyltin oxide to the action of free radicals. It is suggested that the presence of free radicals in the painted and treated wood system may be an important factor in the eventual degradation of tributyltin oxide.
R J Orsler, G E Holland

Fungal Attack on Lignin and Cellulose: Elucidation of Brown- and White-Rot Mechanisms Comparing Biomimetic and In-Vivo Degradation Patterns
2010 - IRG/WP 10-10714
This paper examines research and hypotheses that have been developed over several years on wood degradation mechanisms. This information is combined with new data and analyses to explain why wood decay patterns caused by brown-rot fungi and specific types of white-rot fungi are different. New data, including work with both biomimetic studies on low molecular weight compounds, degradative enzymes, and wood decayed by brown- and white-rot fungi support a role for these compounds, which results in different types of fungal decay. Specifically the presence or absence of low molecular weight phenolate compounds that bind and reduce iron to generate oxygen radicals is related to brown-rot, as well as “selective white-rot” decay of wood. Free radicals generated by the low molecular weight systems are important in opening up the structure of wood in advance of, or concurrent with, enzymatic attack in both brown-rot and selective white-rot decay. “Simulataneous white-rot” fungi do not typically posses a highly expressed low molecular weight phenolate system and this may help to explain the erosion pattern of decay observed in decay by this type of white-rot. New analytical techniques including Pyrolysis-molecular beam mass spectrometry and 13C-labeled tetramethylammonium hydroxide thermochemolysis are used to provide new information, particularly regarding how lignin is attacked, and either repolymerized or solubilized depending on the type of fungal attack. Discussion of the mechanisms involved, and how new wood protection schemes may be developed to exploit these mechanisms is reviewed.
V Arantes, B Goodell, A M F Milagres, Yuhui Qian, T Filley, J Jellison, S Kelley

Susceptibility of angiosperm sapwood to white-rot fungal colonization and subsequent degradation: a hypothesis
1997 - IRG/WP 97-10211
It has long been recognized that angiosperm sapwood in nature is relatively easily and preferentially degraded by white-rot fungi. This susceptibility to white-rot fungi is generally believed to be mainly caused by the structure and concentration of angiosperm lignin. However, an explicit explanation as to why lignin structure makes a particular wood vulnerable to white-rot colonisation and subsequent degradation has apparently never been given. We propose that free phenolic groups in wood, such as those present in the lignin or heartwood extractives, can act as free radical scavengers (antioxidants) which disrupt the various white-rot free radical degradative mechanisms. Consequently the presence of a relatively high free phenolic "density", such as that present in gymnosperm sapwood or angiosperm heartwood, may inhibit white-rot degradation. Conversely, white-rot fungi may find wood with a relatively low free phenolic content, such as angiosperm sapwood, easy to colonize. The complex structure of angiosperm wood, in which different cell types have different amounts and types of lignin -- and consequently different levels of free phenolic "densities" -- influences the susceptibility of angiosperm wood to initial white-rot colonisation and, perhaps, also the subsequent decay rate. In addition to the free phenolic ``density" other factors, some as yet unknown, undoubtedly also affect the decay resistance of a particular wood.
T Schultz, D D Nicholas

The effect of low molecular weight chelators on iron chelation and free radical generation as studied by ESR measurement
2000 - IRG/WP 00-10367
The focus of this work was to improve our current knowledge of the non-enzymatic mechanisms involved in brown-rot decay. Electron Spin Resonance (ESR), also known as Electron Paramagnetic Resonance (EPR), is an attractive technique for the identification and study of chemical species containing unpaired electrons (such as radicals and certain transition metal species). ESR spin-trapping techniques are also commonly used to study very reactive and short-lived free radical species. It has been proposed that low MW chelators as well as Fenton reagents are involved in wood brown-rot decay, at least in early non-enzymatic stages. In this work, the binding between a chelator model compound and ferric iron was studied by ESR spectroscopy. The effects of the chelator model compound, Fenton reagents, as well as the reaction conditions on free radical generation were also studied using ESR spin-trapping techniques. The results indicate: 1. The relative amount of ferric iron bound to chelators is directly related to the chelator / iron ratio in the system. The relative quantity of the chelator-iron complex can be determined by measuring the intensities of the characteristic g4.3 ESR signal. 2. The effects of the chelator/iron ratio, the pH, and other reaction parameters on the hydroxyl radical generation in a Fenton type system could be determined using ESR spin-trapping techniques. 3. Data support the hypothesis that superoxide radicals are involved in the chelator mediated Fenton processes.
Yuhui Qian, B Goodell

Wood degradation mechanisms by the brown rot fungus Gloeophyllum trabeum
1997 - IRG/WP 97-10229
A mechanism for the degradation of wood by the brown rot fungus Gloeophyllum trabeum is outlined. The mechanism includes the function of redox-cycling, low molecular weight phenolic derivatives which sequester and reduce iron in acidic environments. The role of oxalate for the sequestration of iron (hydr)oxides and the pH dependent transfer of iron to the G. trabeum phenolic chelators, as well as for the maintenance of a pH gradient within the cell lumen and wood cell wall is discussed. A hypothesis for the generation of reactive oxygen species from the redox cycling of the phenolate compounds produced by G. trabeum as well as from free phenolics derived from the wood cell wall is outlined. Site specific production of hydroxyl radicals within the wood cell wall is discussed.
B Goodell, J Jellison

Controlling the sapstain fungus Ceratocystis coerulescens by metabolites obtained from Bjerkandera adusta and Talaromyces flavus
1993 - IRG/WP 93-10024
Sapstain causes severe damage to wood and wood products, posing a major economic problem for the wood industry. The purpose of this study was to determine if metabolites from Bjerkandera adusta and Talaromyces flavus would (1) decolorize stain in wood caused by Ceratocystis coerulescens and (2) prevent sapstain by Ceratocystis coerulescens. We studied the interaction of the sapstain fungus Ceratocystis coerulescens against the test fungi Bjerkandera adusta and Talaromyces flavus in dual cultures on agar medium. The metabolites obtained from test fungi were examined on pine veener disks stained by Ceratocystis coerulescens. Our results indicate that the test fungi were antagonistic to the sapstain fungus Ceratocystis coerulescens. The combination of metabolites from the antagonists decolorize the sapstained pine veener disks and killed the existing growth of Ceratocystis coerulescens.
S C Croan, T L Highley

Generation of hydroxyl radical by the brown-rot fungus, Postia placenta
1988 - IRG/WP 1360
In an electron spin resonance (ESR) survey of various liquid cultures and wood slivers innoculated with the brown-rot fungus, Postia placenta, the spin trap dimethyl-l-pyrroline N-oxide (DMPO) was used to detect the presence of the hydroxyl radical. The ESR spectra for the paramagnetic DMPO- hydroxyl radical adduct was observed in (1) nitrogen-limited, liquid cultures having 1.0% glucose or 0.1% cellobiose as the carbohydrate source and (2) fungal infected wood slivers of Douglas-fir (Pseudotsuga menziesii) and white fir (Abies concolor). The 4-line ESR signal had a 1:2:2:1 intensity ratio, 15 G line splitting, and a g-factor of 2.003. The signal was stronger and more stable in wood slivers than in liquid cultures. The effect of free radical scavengers on the DMPO-hydroxyl adduct signal is currently being studied.
B Illman, D C Meinholtz, T L Highley

Targeted inhibition of wood decay (Using everything but the kitchen sink)
1997 - IRG/WP 97-10203
Low molecular weight oxidative decay agents have been implicated in the degradation of wood by brown-rot decay as evidenced by chemical analysis of brown-rotted wood and detection of oxalic acid and hydroxy radicals. Fenton chemistry (H2O2 / Fe++) is often proposed as the mechanism for generating hydroxy radicals. Previous authors have shown iron to enhance the brown-rot hydrolysis of wood, while others have shown suppression of brown-rot by organic and inorganic metal chelators. We have attempted to inhibit brown-rot and white-rot decay of southern pine and maple wood blocks in a series of soil block decay tests using a variety of chemicals targeted specifically at key components of proposed brown-rot mechanisms. Included in these tests were inorganic and organic chelators, calcium coordinating compounds, wood binding dyes, microbial siderophores and common antioxidants -- some previously tested. All chemicals were screened at 1% aqueous (w/v). Only 2 of 28 compounds were effective in significantly reducing wood weight loss by all fungi tested in 12 weeks: napthaloylhydroxylamine (NHA) -- a calcium precipitating agent; and ruthenium red (RR) -- a pectin stain. Both compounds bind preferentially to pit tori and ray parenchyma cells as observed by light microscopy. Targetting the woody substrate for inhibition of decay looks more promising than targetting fungal physiology
F Green III, T A Kuster, T L Highley

Recent development in North American industrial wood preservation plants
1988 - IRG/WP 3467
After remaining static for many years there have been a number of changes in plant design and treating cycles in recent years. This has been particularly true in the USA where few restrictions are placed on plant treating cycles by specifications; since only results type specifications are used. It is also important to realize that the AWPA Specifications for Southern Yellow Pine only call for treatment of the sapwood since the heartwood has a high natural resistance to termites and decay. This is evidenced by old plantation houses on Southern and West Indian sugar Plantation houses that have stood for several hundred years. This paper attempts to set out these changes and the reasons for them. Industry often appears to have jumped ahead of research or the results of research have not filtered down to the industry and these knowledge gaps are mentioned in the appropriate sections. These sections try to separate the many inter-related factors into simple headings covering plant components and other factors influencing treatment. Some of the criteria presented in this paper have only been recently recognized as of importance so that results from past research is often found to be inconclusive when studied under the light of present day knowledge (e.g. rate of pressure rise was not noted).
J F Bridges

Environmentally benign wood preservatives based on organic biocide antioxidant combinations: A brief review of laboratory and field exposure results and discussion of a proposed mechanism
2004 - IRG/WP 04-30335
The combination of various organic biocides with commercial antioxidants generally increased the biocides’ efficacy 2-3 fold against wood-destroying fungi in short-term laboratory decay tests, and some positive results have been obtained after 2-4 years of outdoor exposure. The two antioxidants principally examined, propyl gallate and butylated hydroxytoluene, are low cost and, since both are food additives, benign. The biocides studied have either been examined as potential wood preservatives or are used in commercial wood preservative systems. The purpose of this paper is to: 1) briefly summarize our prior laboratory decay results; 2) briefly discuss results obtained so far from outdoor exposure tests, both above-ground and ground-contact exposure; 3) discuss differences in results between laboratory decay tests and the outdoor exposure data; and 4) propose a mechanism by which antioxidants could protect wood.
T Schultz, D D Nicholas, W Henry, C Pittman, D Wipf, B Goodell

Fungal detoxification of organotin biocides
1985 - IRG/WP 1258
The ability of a range of wood decaying fungi to inactivate bis(tri-n-butyltin) oxide (TnBTO) in the extracellular growth medium, in stationary liquid culture was determined. A distinction between the ability to tolerate the fungicide and to inactivate it was made: the white-rot organism Coriolus versicolor being the most efficient inactivator. In an attempt to determine the extracellular agents responsible for any detoxification, Coriolus versicolor was shown to produce significantly greater levels of extracellular free radicals/peroxidase. Preliminary tests have shown the nature of the associated anion on the fungicide effects the susceptibility of tributyltin compounds to free radical attack in a chemical system. The ability of an free radical scavenger to reduce detoxification in such a system has also been demonstrated.
P S Belford, D J Dickinson

Some fundamental thoughts on the prediction of field performance from lab-testing based on comparison of lab and field test results of some copper-free materials
2003 - IRG/WP 03-20269
In the paper results from lab testing (ENV 807 and EN 113) are compared with field results (EN 252) of differently treated wood. Depending on the type of the organic biocide containing material and depending on type of soil and type of decay differences were found in suitability of the lab methods to predict field performance. The attempt is made to interpret the found differences. Furthermore it is examined to which extend the applied short term tests meet the general requirements for prediction of field performance and in service performance given by CIB/RILEM ISO TC 59. Based on the experimental results reported suggestions for possible adaptations of the currently used methods are discussed.
A O Rapp, U Augusta

The role of oxygen and oxygen radicals in one-electron oxidation reactions mediated by low-molecular weight chelators isolated from Gloeophyllum trabeum.markup
1994 - IRG/WP 94-10086
The KTBA assay for determination of one-electron oxidation activity was used to assay reactions of low-molecular weight chelators isolated from the brown rot fungus Gloeophyllum trabeum. The assay, performed either under air or nitrogen showed that molecular oxygen was an important factor in chelator-mediated oxidation reactions. A reduction in oxidative activity was observed when superoxide dismutase was introduced to the reaction, indicating that superoxide radicals also involved in the reaction and were scavenged by SOD. The KTBA assay showed, similarly to other assays in our laboratory, that the chelators could reduce Fe(III) to Fe(II). However, once chelators were 'oxidized' in this process they appeared to be redox inactive. Preliminary results indicate that chelator redox activity can only be regenerated in the presence of a reductant such as NADH or oxalate.
Jun Lu, B Goodell, Jiang Liu, A Enoki, J Jellison, H Tanaka, F Fekete

Further steps in the development of above ground wood preservative systems
2002 - IRG/WP 02-30300
Metal and organo-metallic wood preservative systems have provided the consumer with cost effective wood preservative systems which satisfy the performance requirements in a wide range of end uses. With increasing environmental and legislative control, metal-free formulations have emerged as the dominant preservative systems for the protection of timber in the lower hazard classes. In higher hazard classes however, and particularly where the preservative is subject to exposure to the elements, susceptibility of these biocides to chemical and biological degradation processes markedly increases the difficulty in the evaluation and eventual determination of wood preservative performance. This paper discusses aspects of the development process required to produce effective wood preservatives with emphasis on unprotected hazard class 3 end uses.
P Warburton, A S Hughes

Free radical process controlled by manganese peroxidase and lipid-related metabolites produced by Ceriporiopsis subvermispora
2001 - IRG/WP 01-10412
Ceriporiopsis subvermispora, a specific lignin-degrading fungus produced free unsaturated fatty acids (USFAs) including 9,12-octadecaienoic asid, together with saturated fatty acids (SFAs) at an incipient stage of cultivation on wood meal cultures. In prolonged cultivation period after two weeks, the amount of intact fatty acids decreased with increasing in organic hydroperoxide and TBARS production. To analyze the free radical reactions of linoleic acid with MnP, the fungal metabolite was reacted with MnP from C. subvermispora and the radicals produced were analyzes by ESR. The in vitro spectroscopic analysis demonstrated that MnP-dependent lipid peroxidation is not initiated by direct ion of hydrogen from bis-allylic position during turnover but proceeds by a Mn(III)-dependent hydrogen ion from enols and subsequent propagation reactions involving the formation of acyl radical from lipid hydroperoxid. This finding expands the role of chelated Mn(III) from a phenol oxidant to a strong generator of free radicals from lipids and lipid hydroperoxides in lignin biodegradation. Possible roles of the free radical reactions in selective lignolysis is discussed.
T Watanabe, M Enoki, S Sato, Y Honda, M Kuwahara, N Shirai, K Messner

Degradation of resin constituents in various wood species by the white rot fungus Bjerkandera sp. strain BOS55
1999 - IRG/WP 99-10301
In previous studies, the white-rot fungus Bjerkandera sp. strain BOS55 was shown to cause extensive degradation of lipophilic extractives (resin) in Scots pine wood. Further research was carried out in order to investigate the ability of Bjerkandera sp. for reducing resinous constituents in various softwood (Douglas fir, larch and spruce) and hardwood species (birch, beech and poplar). The greatest resin reduction occurred in beech (79% in two weeks). High levels of resin elimination were also observed in softwood species like spruce (36%) or Scots pine (35%), as well as in hardwood species like poplar (32%) or birch (24%). In contrast, Bjerkandera sp. only caused a negligible loss of resin components in Douglas fir wood chips. HPLC analysis of acetone extracts from control and fungal-treated samples showed a rapid elimination of triglycerides, diglycerides, free fatty acids and sterols. Toxic constituents in softwood species like resin acids were partially removed in Scots pine, spruce and larch (29-34% in two weeks).
J Dorado, T A Van Beek, F W Claassen, R Sierra-Alvarez

Bethoguard; A new wood protecting fungicide for use in metal free ground contact wood preservatives
2002 - IRG/WP 02-30301
Research has identified the limitations in both the spectrum of activity and permanence of organic biocides placed in wood in high hazard environments, particularly in the absence of heavy metals such as copper. More specifically, the control of soft rot decay in wood in soil contact has proven to be most problematic. The new organic biocide, Bethoguard; an oxathiazine, has demonstrated excellent potential for these end uses and has shown particularly good soft rot performance in both laboratory and simulated field exposure evaluations. During this research, emphasis has been placed on the inclusion of additional active ingredients necessary to complete the spectrum of activity towards other wood degrading organisms such as white rot and brown rot. This paper presents an overview of this molecule as a new wood preservative and presents preliminary results from laboratory screening procedures.
S C Forster, G R Williams, M Van Der Flaas, M Bacon, J Gors

PXTS; A Metal Free Oligomer Wood Preserving System - A Summary of Data To Date
2004 - IRG/WP 04-30350
The world is continually looking for new wood preservative technology, especially to address environmental concerns. Recent changes in the USA have limited the use of arsenical containing formulations to industrial use through a negotiated voluntary cancellation of most residential label uses. PXTS (Polymeric Alkylphenol Polysulfide) offers a brand new technology that is an all organic system, like creosote or pentachlorophenol, but without the associated human toxicity. PXTS has been extensively tested and evaluated over the last 6+ years in both laboratory and field efficacy tests, and has undergone extensive physical and chemical property tests on both the active ingredient and on the PXTS treated wood . This paper summarizes the results of the testing on PXTS and PXTS treated wood through 2003. Lengthy field trials have now proven the efficacy of PXTS in both harsh and very severe test sites where attack is rampant from insects and decay organisms. Additionally, laboratory efficacy tests have shown that the PXTS performance profile is superior to creosote in many applications, extending the life of wood treated with PXTS many fold over that of untreated controls. Laboratory soft rot test indicate that PXTS may be as much as 6 times more effective than AWPA P-1/P-13 creosote. Tests in marine waters, although not presented here, have also proven PXTS superior to creosote in harsh Florida environments riddled with Limnoria. Although work is continuing on the evaluation of this new preservative, this document represents the most complete portfolio of information on PXTS presented to an international audience.
M H Freeman, D D Nicholas, D Renz, R Buff

Paintability and gluability of wood treated with arsenic-free and chromium free preservative treatments
2006 - IRG/WP 06-40342
The objective of this project was to study, in comparison with traditional CCA treatment, the paintability and gluability of wood treated with arsenic-free and chromium-free preservative treatments. Four formulations, all certified CTB P+, were selected in accordance with their representativeness of the preservative product market: one CCA reference formulation and three chromium and arsenic free formulations (S1, S2, and S3). The species of wood chosen was the Scots pine. A wettability study has shown that the four preservative treatments lead to very different surface characteristics. CCA and S1 treatments make wood hydrophobic whereas S2 and S3 make wood hydrophilic. The paintability phase was carried out on six types of coatings including waterborne and solventborne products, paints and stains. The performance of the coatings on the different treated woods was characterised by artificial and natural weathering tests. For the paints tested, the overall appearance of the test specimens after weathering was the same irrespective of the wood preservative. As regards the transparent coatings tested, the general appearance of the test specimens after weathering is generally better on CCA treated wood. However, the adhesion testing showed a tendency toward poorer adhesion for coatings on wood treated with new generation preservatives. The objective of the gluability phase was to qualify: Glue-laminated treated northern Scots pine with RPF, MUF and PU type structural adhesives, used for load bearing structures, Glue-laminated treated regional Scots pine with an EPI type non-structural adhesives, used for joinery. As such, the initial mechanical performance of the different glue bonds was evaluated through shear testing by compression. The durability of the assembly was evaluated by delamination testing. The wood treated with new generation products therefore displays satisfactory gluability with RPF, MUF and PU type structural adhesives. Results are more variable with EPI type non-structural adhesives.
L Podgorski, G Legrand

Chapter 11 - Preservation of talla bamboo
2007 - IRG/WP 07-10635-11
Researches revealed that the talla bamboo (Bambusa tulda Roxb.)) in Bangladesh could be full-cell pressure treated with CCA in green and dry conditions. The dry bamboo gives higher loading absorptions than green one when impregnated at same treating conditions. Also higher absorptions are obtained at nodes rather than internodes. Adequate penetration and retention results for ground and water contact uses are only possible by treating bamboos pre-dried to 10-15% MC. The green bamboo is easily treatable for indoor and overhead outdoor uses. The service life of this socio-economically important bamboo can easily be increased at least two times than nominal by CCA treating either green or dry bamboo. Two small holes made before pressure treatment in each internode will give split-free bamboo.
A K Lahiry

Chapter 12 - Treatment Groups of Bamboo
2007 - IRG/WP 07-10635-12
Study on distribution of CCA in three major bamboo species in Bangladesh, full-cell pressure treated at green and dry conditions revealed two treatment groups and some treating principles. Higher adequate treatment for ground and water contact use is only possible by treating problematic bamboo species pre-kiln dried up to half of its FSP and non-problematic species pre-dried up to FSP (20% MC). The non-problematic species can be treated in green conditions for indoor and overhead outdoor uses. Two smallest holes made before treatment in each internode will give split-free bamboo.
A K Lahiry

The Effect of Water Repellent on Semi-Field Leaching of Active Substances from Metal Free Wood Preservative Formulation
2013 - IRG/WP 13-30615
The risk assessments for the use of wood preservatives proposed by the OECD and used under the Biocidal Products Directive (BPD) (98/8/EC) require the derivation of leaching rates for active substances. These rates are to be used as input data in to agreed exposure scenarios. A comparison of the leaching of active substances from wood treated with a metal free preservative formulation with and without water repellent is presented. The water repellent was selected to have good beading properties rather than conferring dimensional stability. The wood is exposed horizontally in a semi-field test based on the principles of NT Build 509. The volumes of leachates recovered after rain events are analysed to inform a discussion of the action of the water repellent. The leachate analysis data indicate that initially the leaching by natural rainfall is unaffected by the water repellent. However, after approximately 3 weeks (~ 45 mm rain) the leaching of active substances from the wood treated with water repellent is suppressed. After approximately 871mm of natural rainfall, active A shows 25% reduction in leaching and active B shows 24% reduction in leaching. The leaching of active substances from wood in service is an important consideration in environmental risk assessments. These results indicate that the environmental impact of wood preservative active substances can be reduced by the inclusion of water repellents in the formulation.
D G Cantrell

Performance of biocide-free preservative-protective systems modified with organosilicon compounds
2013 - IRG/WP 13-30628
The objective of the research was to determine the influence of organosilicon compounds in preservative-protective systems on the selected properties of pine wood aimed for outdoor use. The investigations were made for biocide-free systems based on alkyd resin and natural oils modified with alkylalkoxy-, amino- and glycidoxysilanes. The special attention was paid on the influence of hydrophobic properties of wood surface on the resistance to abiotic and biotic factors. The scope of the research comprised of wood properties related to water soaking, durability to ageing including water and UV radiation as well as resistance to fungi and microfungi. The study has shown that wood surface treated with the preservative-protective systems containing silanes demonstrated increased hydrophobicity, hence higher resistance to abiotic and biotic factors. Favorable fungicidal properties of the systems allowed to consider them as a good alternative to the conventional preservatives containing fungicides.
B Mazela, P Hochmańska, T Krystofiak

Field performance of wax treated wood
2014 - IRG/WP 14-30649
The durability and outdoor performance of wax treated Scots pine sapwood was investigated in above ground field tests. Therefore wood impregnated with three different waxes was exposed in horizontal lap-joint test which is running since eight years. Durability, wetting resistance and the susceptibility to checking has been investigated. In summary, all wax treated wood performed better compared to untreated material. However, the principle of wood protection through moisture protection became evident in both above ground set ups. Durability and moisture performance were significantly better compared to untreated controls, but diminished with preceding exposure time.
C Brischke, E Melcher

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