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Interaction mechanisms of F/Cr/As/B type preservative and wood
1981 - IRG/WP 3183
The paper reports results of investigations on the fixation of the components of a F/Cr/As/B preservative in wood and its lignin and cellulosic components.
N Ermush, I Andersone

Literature survey on the permanence and distribution of salt-type wood preservatives
1969 - IRG/WP III 1B
The objective of this survey is generally to review some of the more important published work dealing with the distribution and permanence of salt-type waterborne wood preservatives in treated timber. The survey is limited to the major chrome-containing formulations and the classification system proposed by Becker (1964) has been adopted throughout. CK - chromium, copper (copper, chrome); CKA - chromium, copper, arsenic (copper, chrome, arsenate); CKB - chromium, copper, boron (copper, chrome, boron); CFK - chromium, fluorine, copper (copper, chrome, fluorine); CFA - chromium, fluorine, arsenic (fluor, chrome, arsenate); CF - chromium, fluorine (fluor, chrome). The literature compilation covers the performance of these preservatives assessed from laboratory tests, field tests and practical experience; their application and distribution in the treated wood; and their influence on materials such as glues, paints or metals and the wood itself. It is not the purpose of this survey to draw conclusions regarding the relative merits of the various formulations, the choice of a formulation in a given situation depending upon many factors outside the terms of reference of this review, and not all of a technical nature. In general, there is insufficient directly comparable data for a definitive assessment and in the few comparisons available special factors frequently apply.

Study on the treatment of construction timbers by diffusion methods
1983 - IRG/WP 3252
Several species of timber that could be used for constructional purposes have to be pressure impregnated before such use. Pressure impregnation requires expensive equipment, and needs specialized trained operators, etc, which is not possible in most parts of India. Some timbers cannot be pressure impregnated, but can be treated by diffusion. Diffusion treatments could protect these timbers with simple inexpensive apparatus, using local resources and labour. It is our purpose, therefore, to locate such species which are commonly used in India for constructional purposes, and to preserve these by diffusion; to check if the results are satisfactory, and to find a preservative and simple procedure for the treatments of these timbers based on their treatability.
V R Sonti, B Chatterjee

Applications of the shower test. Part B: Results from CC and CCB treated wood: influence of fixation process
1993 - IRG/WP 93-50010
This report outlines the results of shower tests conducted on CC and CCB treated wood. The results indicate the fairly good fixation of chromium and the reasonable fixation of copper in CC and CCB formulations, as judged by the leaching limits within the Environmental Regulations. In general boron leaches to a higher extent than chromium and copper. The shower test has proven to be a useful quality control and research test. It determines reasonably accurately the leaching under simulated conditions and, admittedly from a limited number of tests, it can determine differences between various fixation cycles. Natural fixation, controlled climate room fixation and steam fixation were compared. Overall the sleam fixation process gave the lowest leaching figures although the selection of an appropriate fixation facility is a question for individual companies, taking into account capital, customer base, throughput etc.
W J Homan, H Militz

A suggestion for the improvement of the chemical protection of wooden poles
1987 - IRG/WP 3445
Insufficient drying of white poles in Sweden causes inadequate penetration of the impregnation compounds, CCA salts and creosote, in a varying proportion of the treated poles, and with pretreatment decay present, sooner or later, internal fungal attack in the ground-line zone of the standing poles is the result. The application of a diffusing fungicide in the ground-line zone in connection with the erection of poles would protect the "pockets" of untreated sapwood and thereby create a more uniform performance, delaying the necessity of early inspection and eliminating a considerable number of premature interchangements of poles.
H Friis-Hansen

Effect of boron compounds-furfuryl alcohol treatment of wood on dimensional stability, termite resistance and boron leachability
2001 - IRG/WP 01-40195
Sapwood blocks of Japanese cedar (Cryptomeria japonica) and Caribbean pitch pine (Pinus caribaea) measuring 20 (tangential) x 20 (radial) x 10 (longitudinal) mm were impregnated with furfuryl alcohol (FFA) by a vacuum-diffusion process followed by curing under heating. Boron compounds (boric acid, ammonium borate and ammonium biborate) were mixed in the impregnation solution of FFA. Anti- swelling efficiency, water holding capacity and moisture exclusion efficiency were measured. Boron leachability was determined by ion chromatography with ten leaching cycles according to JIS 9201 (1992). The specimens were exposed to termite attack testing, before and after the cyclic leaching process. The results indicated that FFA imparted to wood greater dimensional stability when mixed with boron compounds. Boron when mixed with FFA behaved differently to boron alone treatment, although it was still leachable. The wood specimens treated with FFA-boron compounds were quite resistant to termites even after severe leaching.
S K Ozaki, M K Yalinkilic, Y Imamura, M F Souza

Leachabilty and efficacy of fatty acid derived boron esters as wood preservatives - leachability and efficacy of fatty acid derived boron esters as wood preservatives
2004 - IRG/WP 04-30351
Borates have many advantages as wood preservatives. However, boron is susceptible to depletion under humid conditions and this restricts its outdoor use. In order to reduce boron leachability in treated wood, one of the anticipative approaches is to use organic fixed boron-based preservatives. This study investigated the leachability of six boron ester compounds as potential preservatives. Scots pine sapwood (Pinus sylvestris L.) test specimens were vacuum treated at different concentrations of BAE (Boric Acid Equivalent) of each boron ester active ingredient with and without 10% addition of commercial resin product. Stand-alone boron treatment using 1% BAE disodium octaborate tetrahydrate (DOT) is conducted as a reference. The results of chemical analysis of leachates taken at different periods showed significant differences in boron leachability between the DOT treated samples and specimens treated with both boron esters. Although there are significant differences between the pure boron treatment and the resin protective addition treatment, minor differences were found between boron ester treatments irrespective of resin addition. However, these data allowed the selection of one boron ester compound for further biotesting based on its leaching performance. Results of the biological assays with both Scots pine sapwood and poplar (Populus trichocarpa x deltoides) samples using the European standard EN 113 confirmed the efficacy of the selected boron ester compound against Coriolus versicolor, Coniophora puteana, Gloeophyllum trabeum and Poria placenta. After sixteen weeks of exposure to fungal attack all specimens treated with the new organic boron compound at 0.66 % BAE, irrespective of resin addition, exhibited insignificant mass loss for all four fungi and both wood species tested, which proved the decay resistance of the treated wood.
A Mohareb, J Van Acker, M Stevens

Bibliography on the use of boron compounds for the preservation of wood
1973 - IRG/WP 315
This bibliography is based on an earlier literature survey prepared by J. Thornton and Wm. E. Bruce (O.E.C.D. Document No. 27/DAS/CSI/M/91) which was enlarged and revised for a meeting in Paris in October 1968 (Document 27/DAS/CSI/M554) by Professor W. Bavendamm of Reinbek. The latter (1968) document with its 166 references has now been extended and brought up to date. Acknowledgments are due to Borax Consolidated Ltd. and to the New Zealand Forest Research Institute who have both helped by providing us with further compilations of their own. Boron compounds have been in use in the past and are still found useful in medicine in the form of boric acid solutions and boracic ointment. They have also been used for the conservation of foodstuffs. In the treatment of wood they were first mostly used as fire retardants. Since the Second World War they have become increasingly important in the field of wood preservation.
R Cockcroft, J F Levy

Borates as wood preserving compounds: The status of research in the United States
1989 - IRG/WP 3542
This paper describes the extensive, on-going cooperative research effort among government and university research laboratories and industry to fully evaluate the potential for borates as wood preservatives in the United States. Research is discussed in terms of laboratory evaluations, field testing and mill trials, pilot plant pressure treatment studies, and remedial treatments. Future research plans are also presented.
H M Barnes, T L Amburgey, L H Williams, J J Morrell

Investigation of copper fixation in timber by sodium nitrit
1992 - IRG/WP 92-3707
Solutions containing mixtures of water soluble copper salts and sodium nitrite have been shown to be capable of producing leach resistant copper treatments when impregnated into timber. A rapid leaching trial showed that copper fixation levels of 85-90% were possible which compared well with the fixation level obtained with conventional hexavelant chromium containing systems in the same test regime. The fixation process appears to be dependant only upon the presence of copper and nitrite ions and is not affected significantly by the nature of the copper salt or other components present. Optimum fixation is obtained with a molar ratio of copper to nitrite ion of between 1:4 and 1:5.
C Waldie, J A Cornfield

Addition of boron compounds and octanoic acid for improvement of biocidal properties and copper fixation at copper-ethanolamine based wood preservatives
2006 - IRG/WP 06-30408
Copper-ethanolamine based wood preservatives became important active substance (formulation) for wood protection, novelty. As copper itself can not ensure sufficient protection against wood destroying organisms and fixation in wood we combine it with other biocides like ethanolamine, boron and octanoic acid. This investigates were performance on spruce wood impregnated with different combination of copper-ethanolamine, boron and octanoic acid in aqueous solution. Copper fixation was determined according to the modified ENV 1250 standard method, while fungicidal testing against Trametes versicolor, Gloeophyllum trabeum and Antrodia vaillantii were performed according to the mini block procedure and termiticidal activity was determined using Kalotermes flavicollis. The results showed that addition of boron increases copper leaching, but on the contrary improves efficacy against wood decay fungi and termites. On the other hand, addition of octanoic acid improves copper fixation, and slightly decreases effectiveness against copper tolerant fungi.
F Pohleven, M Humar

Development of boron/linseed oil combined treatment as a low-toxic wood protection. Evaluation of boron fixation and resistance to termites according to Japanese and European standards
2007 - IRG/WP 07-30448
Combinations of boric acid as a first step of treatment and linseed oil as a second step have been performed in order to enhance boron retention to leaching and wood resistance to termites. Classic leaching and termites resistance standards are inappropriate to evaluate this combination which can be considered as both a wood core preservation treatment and a coating. Japanese Industrial Standard (JIS K1571, 2004) on Japanese cedar (Cryptomeria japonica) Japanese beech (Fagus crenata) exposed to subterranean termite Coptotermes formosanus, and, European standards EN84 and EN117 on Pine (Pinus sylvestris) exposed to termite Reticulitermes santonensis have been performed for the same boric acid/ linseed oil treatments. Addition of oil as a water repellent to boron treated wood gave promising results with about 30% of initial boron retained. Termite mortality rates and efficiency thresholds using the different standards are determined and compared. Moreover, the relevance of Japanese mass loss indicator and European visual evaluation are discussed in the case of unconventional wood protection system such as boron/linseed oil combination.
F Lyon, M-F Thevenon, Y Imamura, J Gril, A Pizzi

Influence of Polyvinyl acetate emulsion (PVA) on boron leaching and fungicidal properties
2008 - IRG/WP 08-30451
Boron compounds are very effective fungicides, but unfortunately they leach from wood. In order to improve boron fixation, boric acid, borax were combined with polyvinyl acetate emulsion (PVA). For comparison copper salts were included into this research as well. Selected preservative solutions were chosen for impregnation of Norway spruce wood specimens (Picea abies). Wood blocks were exposed to three wood decay fungi Antrodia vaillantii, Gloeophyllum trabeum and Trametes versicolor according to the mini block procedure. Part of impregnated specimens was leached according to the EN 1250-2 procedure. The results showed that addition of PVA emulsion slightly improves copper and boron fixation. Spruce wood impregnated with the lowest concentration of boron based solutions (cB = 0.1 %) was found resistant against tested fungi. In contrast, wood blocks impregnated with copper were sufficiently protected against G. trabeum and T. versicolor but not against A. vaillantii. Furthermore, PVA itself has a negative impact on fungal growth, and it improves performance of boron and copper based aqueous solutions.
M Humar, B Lesar, P Kralj

The Comparison of Fixation and Leachability of Bark, Fruit and Leaf Tannin Extracts with Boron Minerals
2008 - IRG/WP 08-30473
Tannins extracted from several plants have natural durability properties. Due to these properties, some of the researchers have studied them for protecting wood. In this study, Scots pine (Pinus sylvestris) and beech (Fagus orientalis) wood samples were treated with bark, fruit, and leaf extracts as well as water-based wood preservative salts at various concentrations to increase fixation. The penetration, fixation, and antifungal properties of different treatment solutions were compared. Retention levels were generally higher for Scots pine wood than beech wood. The highest retention levels were seen in wood treated with valex and sumex, which are extracts of oak fruits and sumac leaves, respectively. Leaching tests indicated that both wood types treated with sumac extracts showed higher retention levels than wood treated with the other fruit and bark extract solutions. Adding 1% water-based wood preservative salts to valex and sumac extracts increased the retention levels. Higher concentrations of wood-preserving salts accelerated and increased the amount of leaching. We found that the extract alone was resistant to leaching. Mycological tests showed that bark extract solution was the most effective at preventing mycelium penetration and that adding water-based wood-preservative salts to all extract solutions significantly affected the resistance of the wood against fungal infection.
S Sen, C Tascioglu, K Tirak

Effects of new fixative additives on leachability of boron wood preservatives
2009 - IRG/WP 09-30507
Borates are well known with their protective capacity against both fungi and insects with low mammalian toxicity and environmental acceptable. However, boron itself does not ensure the appropriate protection for wood in the exterior applications because of their easily depletion from the treated wood under wet conditions. In this study, the potential use of monoglyceride and polyvinyl alcohol products as boron fixative agents was investigated. Two levels of these selected compounds (10%, 15% for the monoglyceride and 2.5%, 4% for the polyvinyl alcohol) were evaluated separately with three boric acid equivalent concentrations (1%, 2% and 4% BAE) in double vacuum impregnation processes using Scots pine sapwood and European beech specimens. Leaching was performed according to a laboratory leaching procedure (ENV 1250-2). Results of boron analysis using atomic absorption spectrometer (AAS) for the wood specimens and the leachates showed a significant reduction in boron leachability for the samples treated with both tested fixation additives when compared to the stand-alone boron-treated specimens. For boron protective additive treatments, the percentages of residual boron ranged from 20% – 37% of the initial boron retention. In all cases for these treatments, the detected boron retentions were above the toxic limit (1 kg BAE/m3) set for wood protection against basidiomycete fungi. Polyvinyl alcohol additive was the most promising product with approximately the same boron fixation effect but at lower levels when compared to the high levels of the tested monoglyceride compound.
A Mohareb, J Henry, E Wozniak, P Gérardin

Effects of polyvinyl alcohol on leachability and efficacy of boron wood preservatives against fungal decay and termites attack
2010 - IRG/WP 10-30526
In this study, the use of polyvinyl alcohol (PVA) as boron fixative agent was investigated. Two levels of PVA (2.5 and 4%) were evaluated with disodium octaborate tetrahydrate (DOT) at three concentrations (1, 2 and 4% boric acid equivalent (BAE) using a double vacuum impregnation processes on Scots pine sapwood specimens. Leaching was performed according to a laboratory leaching procedure. Boron analysis using atomic absorption spectrometer showed a significant reduction in boron leachability for the samples treated with both concentrations of PVA when compared to the stand-alone boron treatment leading to boron retentions capable to prevent wood biological degradations. Decay resistance of the leached specimens was evaluated using the brown rot fungus Poria placenta. Even if complete protection was not fully achieved, an improvement of decay resistance was observed for the samples treated with DOT in presence of PVA. This leak of efficacy was attributed to a decrease in the biological activity for the complexed boron against fungi. Durability of treated wood against termites attack, evaluated using Reticulitermes santonensis, indicated a significant enhancement for the samples treated in presence of the fixative agent comparatively with the pure boron treatment.
A Mohareb, M F Thévenon, E Wozniak, P Gérardin

Tannin resin-boron associations: Leaching and biological resistance
2012 - IRG/WP 12-30587
The easy leaching of boron in wood preservation formulations has allowed to use this fungicide only for short term applications. The recently discovered adduct with flavonoids allows boron to resist longer periods of time within wood and consequently extend its life. Two different leaching treatments were compared and the fungal and termite decay was examined. The biological tests have shown extremely high resistance of the leached samples against both, fungus (Coriolus versicolor and Coniophora puteana). The resistance towards termites (Reticulitermes flavipes ex. santonensis) was also evaluated. A threshold concentration for the efficacy of boron as wood preservative was determined. Furthermore, the solid state 13C-NMR analysis of the tannin resin has permitted to prove the anchorage of boron to flavonoids.
G Tondi, S Wieland, N Lemenager, A Petutschnigg, A Pizzi, M-F Thevenon

Preliminary testing of spiroborate esters as wood preservatives
2013 - IRG/WP 13-30614
Fungicide and insecticide properties of boric acid are known since 30’s of the last century, but high solubility and leachability of inorganic borates limit their use for only applications not directly exposed to liquid water. A number of attempts were made to fixate borate salts into the wood structure but this research topic is still up to date and undiscovered. Water insoluble organoboron esters were tested in laboratory scale as wood preservatives. Although affected by leaching, the studied spiroborate esters were highly efficient even at very low retentions.
D Panov, N Terziev

Aspects of diffusion of boron through wood
1984 - IRG/WP 3298
Boron compounds have been shown to be toxic to a wide range of wood destroying insects and fungi. They are cheap, have low mammalian toxicity and their application in the treatment of wood does not demand specialized equipment. These attributes make them specially attractive to developing countries. Currently, however, little is known about the mechanism of diffusion of boron through wood. Effective treatment with boron preservatives requires good understanding of how the preservatives diffuse through wood. This paper presents a research proposal with the overall objective of determining the relative importance of structural wood components in determining diffusion rates.
S Iddi

Utilization of curcumin for detection of presence of boron in wood
1982 - IRG/WP 3191
It has been shown that curcumin is not a reliable reagent for detecting boron in wood that has been attacked by fungi
M-L Edlund

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

Proposed methodology for the assessment of safety indexes
1990 - IRG/WP 3562
Safety Indexes (SI)s are developped on the same concept as Efficacy Indexes (EI)s: EIs are retentions of wood preservatives (percentages of the critical values "efficacy") which are presumed efficient for a given biological class of risk. In the same way, SIs are retentions of wood preservatives (percentages of the critical values "safety") which are taken as acceptable for human health and the general environment. EIs and SIs as well are derived from different types of bioassays and related to objectives of quality which may be either regulatory or harmonized within the programmes of the Standard Committees (CEN TC/38 for example). Critical Values are characteristics of wood preservatives; EIs and SIs are characteristics of treated wood; they vary with the different classes of risks.
G Ozanne

Strength loss associated with steam conditioning and boron treatment of radiata pine framing
1987 - IRG/WP 3438
The combined effect of included defects and wood moisture content on the strength loss of second rotation radiata pine framing following conventional steam conditioning is investigated. The green Modulus of Elasticity (MOE) is reduced by approximately 13% after steaming. When dried after steaming, however, neither the MOE nor MOR is significantly different from unsteamed dried controls.
M J Collins, P Vinden

Synergistic effect of boron on Streptomyces rimosus metabolites in preventing conidial germination of sapstain and mold fungi
1992 - IRG/WP 92-1565
We evaluated the synergistic effect of boron (4% BAE solution of Tim-Bor or 4% boric acid) on Streptomyces rimosus metabolites in preventing spore germination of sapstain and mold fungi using plate bioassay, Southern yellow pine and sweetgum block tests, and green pine log sections: sapstain -- Ceratocystis coerulescens, Ceratocystis minor, and Aureobasidum pullulans; mold fungi -- Aspergillus niger, Penicillium spp, and Trichoderma spp. Inhibition of spore germination in plate bioassay by metabolites with boron was more effective than without added boron. Treatment of wood samples with the mixture of boron and unconcentrated metabolites also resulted in the synergistic effect and completely inhibited spore germination of sapstain and mold fungi.
S C Croan, T L Highley

Non-pressure treatability of plywood by CCA, CCB and boron
2005 - IRG/WP 05-40295
Study on diffusibility and absorbability of CCA, CCB and boric acid in 3 mm thick 3-ply hardwood plywood at water saturated and air-dry conditions and dipped at same concentration (5%) and same duration of time (12 hours) revealed complete diffusion of all the preservatives at water saturated condition. Only the CCA-C was found absorbed by the plywood at air-dry condition. The rate of absorption and diffusion of CCA-C was found about 4.5 times higher than CCB and boric acid.
A K Lahiry

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