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Water-based wood preservatives for curative treatement of insect-infested spruce constructions
1998 - IRG/WP 98-30171
On laying down sanitation measures for wooden constructions infested by wood boring insects, we must take into account static risks for the construction - and, thus, for the security of the user - as well as risks for humans and environment due to the chemical preservative compounds of the treated wood. Analyses on many roof constructions made with spruce (Picea abies L.) have revealed that Hylotrupes bajulus L. and Anobium punctatum De Geer have not the significance given to them for decennies. That often allows to replace solvant-based with water-based wood preservatives in old buildings, for the protection of humans and environment. Therefore, a method has been developed in Switzerland for testing wood preservatives with delayed curative efficacy against the house longhorn beetle. Like the European Anobium Standard EN 370 this method intends to prevent the emergence of Hylotrupes beetles. Laboratory tests with diverse water-based wood preservatives available on the market in Switzerland have shown that particularly boron and benzoylphenylurea derivatives containing products get a sufficient penetration in the wood and prevent the emergence of the beetles.
E Graf, P Manser, B Lanz

Potentialities of protein borates as low-toxic, long-term wood preservatives - Preliminary trials
1999 - IRG/WP 99-30212
Boron compounds are efficient wood preservatives, as well as safe for the mammals and environmentally acceptable. Their natural solubility allows them to treat almost any wood species, but is also the cause of their high depletion from treated timber in outside exposure. In order to reduce this leachability, potentialities of proteinic polymer networks retaining boron within the wood have been investigated. Several mixtures of boric acid and proteins (including ovalbumin, collagen, casein, soya flour) have been used to treat pine sapwood miniblocks. The insoluble networks were obtained by protein gelation or coagulation, induced by a physical and/or a chemical factor. These systems appeared to retard boron leaching, the decrease of the leachability rate depending on the protein and the denaturing agent involved in the network creation. The best results have generally been observed for the irreversible heat-induced protein gels. These associations are also able to conserve some boron mobility and activity. Accelerated biological tests of leached wood samples showed good durability performances against Basidiomycetes. The use of protein borates seems to be an interesting basis for low-toxic wood preservatives. Furthermore, in some cases, proteins could add their anti-nutritional factors to boron efficacy to enhance wood protection.
M-F Thévenon, A Pizzi, J P Haluk

The rate of redistribution and loss of leachable preservatives under service conditions
1993 - IRG/WP 93-30026
This paper describes experiments carried out to determine patterns of preservative redistribution and any associated losses which occur when wood containing unfixed water-soluble wood preservatives is exposed to service conditions where leaching is possible. Scots pine sapwood treated with disodium octaborate was used as a model system. Results are recorded and discussed for trials representing painted joinery out of ground contact and unpainted stakes half buried in the ground. The results indicate that in the painted samples out of ground contact the water-soluble compound was redistributed longitudinally and away from the joint zone during the first months of exposure, although little redistribution occurred laterally. No difference in redistribution patterns could be associated with paint type. Ground contact stakes showed a loss in the water-soluble compound of about 40% in the first six months exposure. Most of this appeared to occur from the surface zones of the stake exposed to the weather, particularly from the extreme top. In addition, the compound appeared to migrate upwards from the below-ground portion of the stake to the above-ground portion. These results provide new information on the extent of movement of water-soluble preservatives in painted, jointed timber out of ground contact and in unpainted timber in ground contact. It is concluded that the long-term significance of the observed redistribution effects for painted joinery should be evaluated to confirm that there is no likelihood of shortcomings in performance in practice. For the ground contact situation, results confirm that rates of redistribution and loss are high enough to indicate inappropriateness of such materials for practical use without associated technologies to reduce mobilities.
R J Orsler, G E Holland

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.

Developments in wood preservation processing techniques in New Zealand
1980 - IRG/WP 3143
P Vinden, A J McQuire

Chemical analyses of IRG/COIPM INTERNATIONAL MARINE TEST (to determine the effect of timber substrate on the effectiveness of water-borne salt preservatives in sea-water) samples
1987 - IRG/WP 4114
Chemical analysis of CCA and CCB treated timber was carried out after exposure at tropical and temperate marine sites. Results indicated that losses of all elements had occurred. In particular, losses of boron were severe. Arsenic and copper were also lost. The chromium components in both formulations was the most dominant metal remaining. The results suggest that chromium modification was important in timber treatments for the marine environment, since there appeared to be little difference in timber protection between the CCA and CCB systems.
L E Leightley

Assessment of the toxicity of some copper-, zinc- and boron-based wood preservatives to the cellar fungus Coniophora cerebella Schröet
1974 - IRG/WP 242
This article reports the use of a method based on the determination of the probability of the protection of timber against destruction by fungi. By converting the probability values to probit values and plotting them as a function of the amount of preservative retained in the timber, curves of the toxic effect are obtained, enabling any timber protection probability to be assessed.
V N Sozonova, D A Belenkov

Comparison of the effects of borate, germanate and tellurate on fungal growth and wood decay
1992 - IRG/WP 92-1533
The tetra-hydroxy borate ion is known to undergo complexation with polyols and has been shown to inhibit dehydrogenase enzymes in this way. It has been previously suggested that this complexation is responsible for the inhibition of fungal growth and the protection of boron treated timber. Other ions that have the ability to complex with polyols have also been shown to inhibit dehydrogenase activity. The effect of two of these ions on fungal growth and wood decay was compared to that of borate. It was found that both germanate and tellurate could reduce fungal growth and provide protection of wood against decay at similar molar concentrations as borate. The results have been used to further develop our understanding of the mechanisms of action of borate wood preservatives and substantiate the theory that borate ion/polyol complexation is responsible for the protection of boron treated timber.
J D Lloyd, D J Dickinson

Inorganic preservatives in wood dust - Cause of nasal cancer?
1997 - IRG/WP 97-50085
Since 1985 dust particles from beech and oak trees have been classified by the Senate Commission of the German Research Council (DFG) as being ,,working materials which are definitely carcinogenic to humans". All other wood dusts, including those from softwoods, are classified as being materials ,,with reasonable suspicion of carcinogenic potential". The carcinogenic principle of action continues to remain unclear despite some partial findings of new studies. The load of wood dust with non-genuine chemicals especially heavy metals is one of a number of possible triggering principles. This study describes wood dust collected in 33 German wood processing companies, with regard to concentration of the dust in the air and load of the dust with chromium, copper and boron. More often than expected the machining of preservative treated wood was found. Besides wood preservatives other sources of contamination of wood dust have been identified. Woodworkers are exposed to higher levels of chromium, copper and boron than average citizen, but are far away from threshold values. The heavy metal exposure levels found seem to be unlikely the sole carcinogenic principle of action.
A O Rapp, K Brandt, R-D Peek, U Schmitt

Observations on the performance of copper-based wood preservatives in fungal cellar (soil-bed) tests
1994 - IRG/WP 94-20047
Fungal cellar (soil-bed) tests are considered to be an important tool for the evaluation of the performance of ground contact wood preservatives. Facilities of this type have been established world wide although caution has been exercised in their introduction into standard testing methods for the approval of wood preservatives. This is the result of concerns over the variability in the biological activity between different facilities, and thereafter the determination of effective preservative retentions. This paper presents results of tests on copper based wood preservatives from four different fungal cellar facilities. The results show consistent trends in preservative performance and the high decay rates demonstrate the value of this type of test in determining the potential of new wood preservatives for long term protection in ground contact.
G R Williams, D Rudolph, M E Hedley, J A Drysdale, R F Fox

Borates as wood preservatives - an environmental, health and safety perspective
1993 - IRG/WP 93-50001-03
Boron compounds are highly effective wood preservatives and have an established safe use in the timber treatment industry. Their widespread background occurrence in nature, low acute mammalian toxicity and useful properties make them versatile active ingredients within today's environmentally aware society. A critical review of health, safety and environmental data on the borates, their use and eventual disposal is used to illustrate many of the issues that have to be addressed by the chemical industry today in assessing the performance of their products in the marketplace. This current state of knowledge is contrasted to the detailed requirements of life cycle analysis with an assessment made of its future role in environmental management.
J B Rainer

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

Effect of thickened boron in preventing conidial germination of sapwood-inhabiting fungi
1994 - IRG/WP 94-30059
We evaluated the efficacy of thickened boron preservative "Diffusolä" in preventing conidia germination of sapwood-inhabiting fungi using plate bioassay, Southern Yellow Pine and sweetgum block tests, and green pine log sections. The test fungi were sapstain fungi Ceratocystis coerulescens, Ceratocystis minor, and Aureobasidum pullulans and mold fungi, Aspergillus niger, Penicillium spp, and Trichoderma spp. Conidial germination were inhibited in plate bioassay by Diffusol. Treatment of Southern Pine and sweetgum blocks and green pine log sections with a 10 percent boric acid equivalent of Diffusol inhibited conidial germination of sapstain and mold fungi. In the field exposure, the same Diffusol treatment of green pine log sections inhibited natural basidiospore and conidial germination of forest-inhabiting fungi, thus preventing wood discoloration and deterioration
S C Croan

Protection of rubberwood timber. Part 1: Impregnation with boron preservatives
1989 - IRG/WP 3551
Rubberwood (Hevea brasiliensis) were treated with a 3% proprietary mixture of borax/boric acid using three different treatment schedules i.e. full-cell, full-cell to refusal and full-cell with 12 cycles of vacuum/pressure. Freshly cut samples had mean preservative retentions of 187 kg/m³, 214 kg/m³ and 178 kg/m³ respectively. Pre-air dried samples for one week had retentions of 252 kg/m³, 308 kg/m³ and 282 kg/m³ respectively. An increase of pressure time from 45 minutes to 90 minutes allowed for slightly higher retention values. Preservative retentions of the core (20 mm² around the centre) from freshly sawn samples were 0.08-0.13% m/m BAE (boric acid equivalent), 0.04-0.19% m/m BAE and 0.04-0.21% m/m BAE for the full-cell, full-cell to refusal and full-cell with 12 cycles vacuum/pressure treatment respectively. Retention values of similar samples from the surface up to a depth of 10 mm were 0.36-1.51% m/m BAE for the 3 different treatments.
L T Hong, C C K Liew

On the use of probit analysis for assessing the toxicity of wood preservatives
1974 - IRG/WP 244
To elucidate the general character of the action of the toxic material on the fungus, it is sufficient to carry out preservative tests using the previously described procedure, but in doing so, it is necessary somewhat to change the number of specimens and their arrangement in jars. Five concentrations of toxic material are tested simultaneously. For the testing of one preservative ten jars should be used in each of which are placed 50 specimens, comprising 10 of each of the five concentrations. The proposed arrangement of the specimens in jars makes due allowance both for the variation in the reaction of the individual sections of the mycelium in one jar (ten specimens) and for the variation in the reaction of the fungus in the different jars (ten groups of specimens). The effect of each concentration of toxic material on the fungus may, therefore, be assessed from the result of observing its reaction on a hundred specimens tested in all ten jars. With this procedure the author investigated the toxicity to Coniophora of sodium fluoride, sodium chloride and sodium silicofluoride, copper sulphate, zinc chloride, ammonium fluoride and ammonium pentaborate. The results are given in Table 1. Complete curves of the toxic effect were not obtained for all the formulations, but for the majority of them levels of transition from incomplete to practically complete protection of the timber against destruction by the fungus were established. The test results for sodium fluoride, using the given procedure, are represented graphically in Fig.1 (curve 2). It can be seen from Fig.1 that the change of reaction of Coniophora in timber containing different amounts of NaF is well described by an S-shaped curve, similar to the integral function of a normal distribution. Similar graphs are also obtained when testing other preservatives. The nature of the curve shows yet again that different probit-analysis methods may be used when testing preservatives in timber. Fig.3 shows the probit curves of the effect of sodium fluoride. Since in our case the curve is symmetrical and not lengthy, there was no need to use a logarithmic scale for the axis of abscissae. It can be seen from Fig.3 that, by using a normal distribution as a model for transforming the NaF toxic effect curve, rectilinear graphs are obtained. With such graphs it is easy to find the different levels of timber protection, and also to assess the variation of the reaction of the wood-destroying fungus by computing the mean dose and the standard deviation by the known methods of probit-analysis. From the probit v. NaF content graph (Fig.3) is found the amount of sodium fluoride necessary for protecting the timber of pine sapwood against destruction by Coniophora in 95 per cent of cases. It is 0.168 kg/m³. When determining the said level of protection by the author's proposed procedure, the value obtained was 0.136 kg/m³, i.e. 0.032 kg/m³ less. This is due to the fact that in the latter case the number of specimens tested was comparatively small. The proposed method, therefore, gives an overall picture of the protection of the timber by a specific preservative against the action of wood-destroying fungus and enables the amount of toxic material, which should be selected for a more detailed investigation by the previously reported procedure, to be determined.
D A Belenkov

The extraction of boron from treated wood for quantitative analysis: A comparison of procedures
1992 - IRG/WP 92-2414
The extraction of boron preservative from treated rubberwood and scots pine samples was compared using methods based on refluxing and extraction in 1N NaOH or distilled water at 80°C. The extract solutions were analysed by Inductively Coupled Plasma spectroscopy (ICP/AES). A simple extraction procedure based on immersion of wood samples of approximate dimension 2 x 1 x 1 cm³ in distilled water at 80°C was found to give boron retention values comparable to values calculated from solution absorption and values from analysis of the internal standard extract (refluxed). The practical advantages of the simple hot distilled water extraction method are outlined.
R J Murphy, D J Dickinson, P W McCormack, M K Lung

Preliminary screening of a boron based wood preservative for biological efficacy (fungicidal) in treated timber
2006 - IRG/WP 06-30396
The resistance of Pinus radiata D.Don sapwood blocks, treated with a boron based preservative, to attack by five wood destroying fungi (Fomitopsis lilacino-gilva, Coniophora olivacea, Gloeophyllum abietinum (boron resistant), Serpula lacrymans and Perenniporia tephropora) was investigated. A phenyl pyrazole termiticide (fipronil) was also incorporated into the formulation to examine if its presence affects biological efficacy. The raw linseed oil, liquid wax, terebene and trimethyl borate formulation inhibited decay by the trial fungi. Incorporation of fipronil did not impact the fungicidal properties. Fipronil alone exhibited no fungicidal activity. Further investigation of the preservative formulation is currently being carried out by evaluating field test stakes from an ongoing graveyard trial.
S R Przewloka, J A Hann, P Vinden

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

Synthesis of boric acid ammonium oleate salt for wood preservation: Leachability and termite resistance test
2007 - IRG/WP 07-30435
A new chemical compound coupling boric acid and oleic acid through a joint of ammonium salt has been produced and its synthesis followed and validated by Fourier Transformed Infra Red (FTIR). This compound named ammonium borate oleate (BAO) combining biocidal properties of boron and water repellence of fatty acids has then been studied as a wood preservative. Synthesis of BAO involved different molar rates of oleic acid to determine the best formulation regarding boron retention and resistance to termites. Formulations including four moles of oleic acid for one of boric acid and one of ammonia (1:1:4) have shown the best efficiency compared to formulations 1:1:1, 1:1:2 and 1:1:3 with about 52% of boron remaining after weathering when other formulations retained respectively 10%, 29 % and 46% of boron in the case of an impregnation of Japanese cedar sapwood specimens. Seven solutions of 1:1:4 BAO in ethanol of different concentrations were then produced and impregnated sapwood blocks of C.japonica and F.crenata exposed subterranean termites Coptotermes formosanus. Toxicity threshold around 2.0 Kg/m3 BAE for F.crenata and 2.4 Kg/m3 BAE for C.japonica are a bit lower than toxicity thresholds found in previous studies from 2.0 to 4.5 Kg/m3 BAE indicating that boron is available despite its combination with fatty acids. Extremely low mass losses indicate a positive effect of this combination, hydrophobic effect of oil reduces termite attack and boron leaching when boron provides a biocidal protection. Termite mortality rates recorded along the three weeks of exposure precised the action mechanism of BAO as an intermediate between biocidal boric acid and non toxic fatty acid. Termite mortality rates increase with BAO concentration but an inflexion occurs for highest concentrations due to high oil content.
F Lyon, A Pizzi, Y Imamura, M F Thevenon, S N Kartal, J Gril

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

Smart hydrogels from low molecular weight amphiphilic compounds: toward a solution to decrease leachability and increase efficacy of boron preservatives?
2012 - IRG/WP 12-30589
A new catanionic system associating amphiphilic carnosine (AlaHisC8) and lauric acid forms supramolecular hydrogel at very low concentration. This gel was investigated and we have checked the validity of the concept of hydrogels utilization to reduce boron leachability and to develop new wood protection treatments. Impregnation with 5% aqueous borax solution (w/w) and 0.3% gelator agent (w/w) allows to improve resistance of Scots pine sapwood subjected to water leaching towards the brown rot fungus Poria placenta, while samples treated with 5% aqueous borax solution were partially degraded by the fungus. These results clearly indicate the effectiveness of hydrogel to retain boron in wood.
F Obounou Akong, P Gérardin, C Gérardin-Charbonnier

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

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