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A behavioral assay for measuring feeding deterrency of a slow-acting biocide, A-9248, against the Formosan subterranean termite (Isoptera: Rhinotermitidae)
1988 - IRG/WP 1366
Concentration-dependent feeding deterrency of a slow-acting compound, A-9248 (diiodomethyl para-tolyl sulfone) was studied in a choice test against the Formosan subterranean termite, Coptotermes formosanus Shiraki. A-9248 was a feeding deterrent at concentrations ³8,000 ppm. Initially, Coptotermes formosanus fed on wood treated with 1,000-6,000 ppm A-9248 but learned to avoid the treatment as a result of ingesting sublethal doses of A-9248. Only those groups exposed to wood treated with <1,000 ppm continued feeding on the treated substrates, and ingestion of these concentrations resulted in 85-100% mortality at the end of the 4-week experiment.
N-Y Su, R H Scheffrahn


Evaluating the natural durability of a number of lesser known species of Ghanaian hardwoods using a short term laboratory assay
2004 - IRG/WP 04-10540
Resistance of a number of Ghanaian hardwoods to attack by the crustacean Limnoria quadripunctata was assessed by measuring the production of faecal pellets under forced feeding conditions over a two week period. Small sticks of commercially available, lesser known timber species, were leached in seawater for one week then placed in a cell culture chamber with one animal and 4 ml of seawater. At intervals, the number of faecal pellets per chamber was counted. The number of pellets produced by animals feeding on Scots pine sapwood, which is non-durable, and on greeheart or ekki, timbers with a reputation for resistance to marine borer attack, were used as a basis for comparison. Mortality rates were also compared. Lower pellet production rates and higher mortality rates were taken as measures of natural durability. Feeding on ekki (Lophira alata), kusia (Nauclea trillesii) and ananta (Cynometra ananta) was about one tenth of that on Scots pine. Mortality of animals with wonton (Morus mesozygia) was 90%, but high mortality did not occur with any of the other species.
J R Williams, S M Cragg, L M S Borges, B Shayler


Preliminary screening of diffusion formulations for the control of soft rot
1978 - IRG/WP 2104
We have an urgent need in Australia to develop in situ remedial treatments for the present population of in-service transmission poles. For various reasons we have opted for formulations which can be applied as bandage treatments and thus we are primarily concerned with assaying diffusable toxicants. Two basic approaches have been made: an assay of the formulation&apos;s toxicity; and a combination assay of the formulation&apos;s diffusibility and toxicity. Of the direct assay methods the filter-paper technique is the more rapid although with highly soluble formulations some leaching of toxicants will occur during the preparatory stages and probably during incubation also. Furthermore, filter papers are not strictly comparable to wood, and a modification we have considered is to use &apos;papers&apos; prepared from mechanically beaten pulps rather than chemically degraded pulps. An additional modification would be to substitute veneers for filter papers, although this may give rise to surface concentration effects since the veneers could prove difficult to impregnate homogeneously. By far the most valuable technique for our own screening programme of potential toxicants to control soft rot in standing poles is the Petri dish/wood slab technique. While agar diffusion systems are rapid and provide valuable &apos;short list&apos; data, the information obtained on diffusion rates cannot easily be applied to solid wood. Da Costa&apos;s slab technique is obviously advantageous in this respect. Furthermore, it can be so tailored that successive inocula can be sequentially assessed, thereby providing added information on component diffusion as well as total formulation movement. However, care must be taken in interpreting the data since it is not possible to distinguish directly which chemicals in a mult-component formulation have diffused first and hence which are the toxic ones. Similarly, it could be necessary to impose a time restriction on the test with certain types of formulations.
H Greaves


Towards a colour assay of wood degradation
1982 - IRG/WP 2180
A colour assay for the enzyme catalase is described. Since the activity of this enzyme has previously been shown to be correlated with degree of wood degradation as determined by other methods, this assay may provide a rapid quantitative indicator of superficial and internal wood decay.
M A Line


A rapid colorimetric assay for mold spore germination using XTT tetrazolium salt
2011 - IRG/WP 11-20462
A rapid colorimetric assay was developed to quantitate metabolic activity in mold spores during germination using 2,3-Bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[9phenyl-amino)carbonyl]-2H-tetrazolium hydroxide (XTT). The assay was used to demonstrate inhibition of spore germination following exposure to different biocides and variability in the inhibition of spore germination of different mold species to the same biocide.
C A Clausen, V W Yang


ATP assay for the determination of mould activity on wood at different moisture conditions
1992 - IRG/WP 92-2397
To determine fungal responses to fungicides and environmental conditions and for detection of microbial activity in wood, sensitive and objective methods are needed. We have developed a suitable assay based on analysis of adenosine triphosphate (ATP) by using the luciferin-luciferase reaction. With the aid of this assay the activity of Penicillium brevicompactum on wood at different RH levels was studied. The ATP content in a two week old culture responded quite rapidly to changes in humidity. The ATP content in the colony moved to 70% or lower RH for one week was 10 times lower than the ATP content in the colony kept at 100% relative humidity for the same time period. Increasing the humidity level to 100% RH one week before the ATP determination from a period at lower humidities did not result in a significant increase in the ATP content. This probably indicates that the mycelia of the fungus did not survive the low humidity treatment.
J Bjurman


An appraisal of methods for environmental testing of leachates from salt-treated wood; part 1
1998 - IRG/WP 98-50115
The magnitude and diversity of leaching tests with salt-treated wood, performed by institutes as well as industry, strongly appeal for harmonisation towards one single method. That procedure should be well-defined, cost- and time-effective and moreover be extended with a clear detection and interpretation scheme. The paper(s) presented here tend to evaluate 2 existing leaching methods, the ENV 1250.2 and the EN 84, for their potential use as an environmental standard in high hazard class wood preservation. The leachates obtained are chemically examined for their patterns and levels of metal emission and are biologically screened for their releavance towards in service biomonitored samples. Upon strengthening the objectives and characteristics of the EN 84 ageing test, the results reported here justify the support and upgrading of this procedure as an early stage leaching method within the standard efficacy testing of new or renewed wood preservatives.
G M F Van Eetvelde, M Stevens, F Mahieu, H-W Wegen, A Platen


Oxalic acid quantification, oxaloacetase assay and ESI localization of P, C, and Fe from the brown rot fungus Postia placenta
1994 - IRG/WP 94-10063
The mechanism by which brown-rot fungi initiate depolymerization of holocellulose in wood remains unknown. Recently, oxalic acid (OA) has received considerable attention in cellulose breakdown by brown-rot fungi. The OA could serve as a proton donor for hydrolytic or an electron donor for oxidative (Fenton&apos;s reaction-H2O2/Fe2+) cleavages of cellulose. The acid may originate via oxaloacetase&apos;s action upon oxaloacetate. We report electron microscopic imaging (ESI) to localize Fe and HPLC/oxalic kit colorimetry to purify/quantify OA from hyphae upon agar, southern pine wood blocks (WBs) or in liquid culture. Comparative ESI at 25, 59, 110, 222, and 710 ev of hyphae grown upon agar or WBs demonstrated hyphal Fe (710 ev). Although Fe was not visualized in cell walls of uninoculated WBs, it was in certain wood cell walls of inoculated WBs. The Fe distribution differed from C and P. Oxaloacetase activity was not observed in either Amicon YM10 filter-retained intra-or extracellular fractions of liquid cultured hyphae or in homogenates from decayed WBs. In contrast, HPLC detected OA in both Postia placenta liquid cultures and decayed WBs. The less sensitive oxalic kit (mg vs. ug) did not detect OA in liquid cultures. These results constitute additional evidence for an OA Fe2+/H2O2-Fenton&apos;s mechanism for brown rot-induced cellulose degradation. However, OA&apos;s origin was not established.
C R Jordan, W V Dashek, T L Highley


Early detection of brown-rot decay in southern yellow pine using immunodiagnostic procedures
1990 - IRG/WP 2356
Immunodiagnostic procedures have been used to detect incipient decay of southern yellow pine by six common brown-rot fungi. Rabbit polyclonal antibodies were raised to liquid culture fractions of the six fungi. The antibodies, after preadsorption to sawdust, were tested in particle agglutination assays, immuno-dot blot, and ELISA for their·ability to detect the decay organisms when they were grown in southern yellow pine. Results were correlated to wood block weight loss. Each method specifically detected five of the six test organisms at very low wood block weight loss. Agglutination assays were the least effective and lacked the sensitivity of the other assays, even though the latex particles were more sensitive and reproducible than charcoal particles. Cross-reactivity was only noted for one of the control organisms and only in the charcoal agglutination assay. Both dot blot and ELISA were sensitive test methods, but ELISA had the advantage of quantification. We feel that two of these assays, latex for presumptive results and ELISA for definitive results, could effectively detect incipient decay of common brown-rot fungi.
C A Clausen, F Green III, T L Highley


Comparing the resistance of a number of lesser known species of tropical hardwoods to the marine borer Limnoria using a short term laboratory assay
2003 - IRG/WP 03-10500
Naturally durable species of timber are used as an alternative to preservative treated timber for marine structures, but many species have not been evaluated for their potential for use in this environment. EN 275 specifies a 5-year test period - too long a period for screening tests to be economically viable. In this study, durability was assessed by measuring the production of faecal pellets by the crustacean Limnoria quadripunctata under forced feeding conditions over a number of days. Small sticks of a wide range of wood species, mainly of South American origin, were leached in seawater for one week then placed in a cell culture chamber with one animal and 4 ml of seawater. At intervals, the number of faecal pellets per chamber was counted, and the dimensions of the faecal pellets were measured. The number of pellets produced by animals feeding on Scots pine sapwood, which is non-durable, was used as a basis for comparison. Mortality rates were also compared. Lower pellet production rates and higher mortality rates were taken as measures of natural durability. Some lesser known species performed as well or better than species with a reputation for durability in the marine environment.
L M S Borges, S M Cragg, J R Williams


The biological effectiveness of wood modified with heptadecenylsuccinic anhydride against two brown rot fungi: Coniophora puteana and Gloeophyllum trabeum
1992 - IRG/WP 92-3705
A modified soil block test was carried out using wood samples reacted with heptadecenylsuccinic anhydride (ASA). This modification gave good resistance to decay brought about by the brown rot fungi Coniophora puteana and Gloeophyllum trabeum during the twelve week exposure period. Results indicated that there was a good correlation between increased loading of modifying reagent and an increase in effectiveness paralleled by a marked reduction in wood moisture content. The effective resistance threshold level was calculated to be about 30% weight gain of ASA. Further discussions regarding the mode of action are included.
C Codd, W B Banks, J A Cornfield, G R Williams


Preliminary evaluations of a small wafer assay for screening potential biological control agents
1989 - IRG/WP 2332
Screening potential biological agents for controlling wood decay fungi poses a dilemma. The ideal test would eliminate as many variables as possible. Most tests utilize pure cultures of the test organism on an artificial media which in no way resembles wood. The use of sawdust improves this approach, but the sawdust increases fungal access to the lignocellulose matrix, potentially inflating the importance of fungi which might not compete in the normal wood system. This report describes a simple wafer sandwich assay in which small test wafers colonized by the potential biocontrol agent and a Basidiomycete are placed above and below a sterile test wafer on moist soil in a glass petri dish. Weight loss of the middle wafer is used as a measure of biocontrol potential. Preliminary trials indicate that several previously identified biocontrol agents performed well in this test, inhibiting wood weight losses by both white and brown rot fungi. Because the wood structure is not disturbed, this method could also be used to screen wood treatments which might enhance colonization by the biological control agent.
C M Freitag, J J Morrell


Improved preservative penetration of spruce after pre-treatment with selected fungi. I. Fungal pre-treatment of pole sections
1998 - IRG/WP 98-40117
European spruce logs were pre-treated with either Phanaerochete chrysosporium, Dichomitus squalens, Trichoderma viride and Trichoderma aureoviride for incubation periods of between 1-4 weeks prior to pressure treatment with creosote in a commercial treatment plant and analysed for strength and creosote uptake (see part II Tucker et al.). A method to pre-treat logs was optimised. The pole sections were surface sterilised, inoculated with a spore suspension or blended fungal mycelium and supplemented with a nutrient solution. The colonisation of the logs was investigated by light microscopy, SEM and by an ergosterol method, quantifying the fungal biomass in the wood. The assays indicated a rapid and even colonisation of the wood down to the heartwood within a period of approximately 1 week. Dichomilus squalens was also seen to colonise the heartwood. The microscopic and quantitative assays correlated well and reflected the depth of penetration of creosote on subsequent treatment. SEM observations showed that the increased permeability is due to an enzymatic opening of the pit membranes rather than physical penetration of the pits by fungal hyphae.
B Rosner, K Messner, E J B Tucker, A Bruce


Comparison of two laboratory methods for screening potential anti-sapstain chemicals
1993 - IRG/WP 93-10036
Two methods were used to screen a number of potential anti-sapstain chemicals in the laboratory. In one method miniature boards of freshly felled Scots pine sapwood were dip treated with the candidate chemical, sprayed with a suspension of stainers or moulds and incubated for five weeks. In the other method antibiotic assay discs were treated with precise quantities of chemical, plated out on malt extract agar, inoculated with a spore suspension of one of four stainers and moulds and incubated for a few days. This was repeated for each of the four fungi. The results obtained from the two methods provided information on different aspects of the chemicals but the overall conclusions on efficacy were the same.
S M Gray, D J Dickinson


The potential application of rapid gas-chromatographic assay of microbial respiration to the monitoring of wood decay in field trial situations
1983 - IRG/WP 2196
Gas chromatographic detection of microbial activity (C02 production) within stakes in a field trial situation would appear to provide a sensitive, non-destructive and relatively rapid method for the quantitative assessment of preservative treatments. Most consistent results were obtained when stakes were removed from the soil, washed, saturated with water and incubated in sealed PVC tubes at 25°C for 24 h prior to assay of gas samples from the tubes. Each assay took 1.6 min to perform and stakes were returned to the field within 48 h. Microbial activity was readily detected in untreated Eucalyptus regnans stakes after 18 days field exposure. Stakes pressure impregnated with CCA, busan-30 or creosote displayed consistently low levels of activity to the present time (3 months after insertion).
M A Line


Degradation of polycyclic aromatic hydrocarbons by laccase
1998 - IRG/WP 98-10267
The degradation of polycyclic aromatic hydrocarbons (PAH) by laccase was investigated. Laccase catalyzed oxidation of phenanthrene, solubilized in the surfactant Tween 20, exhibited an absolute requirement for the mediator compound 1-hydroxybenzotriazole. When Tween 80 was used as the solubilizing agent, the oxidation rates were more than six times higher as compared to Tween 20. Using the thiobarbituric acid (TBA) assay, it was shown that the laccase-HBT couple peroxidized linoleic acid. The results suggest that unsaturated fatty acids present in Tween 80 are responsible for the enhanced degradation of phenanthrene by laccase-HBT. The system comprising laccase, HBT, and Tween 80 was applied to the sixteen EPA priority PAH with the result that all of the PAH were extensively degraded.
S Böhmer, E Srebotnik, K Messner


Effect of fungal degradation on the chemical composition of acetylated beech wood
2003 - IRG/WP 03-40267
This study investigated the impact of fungal attack on the chemical composition of acetylated wood. Beech wood acetylated to different degrees was exposed to decay by the white-rot fungus Trametes versicolor under solid-state fermentation conditions. Laboratory soil-bed assays were also conducted to study the degradation of acetylated wood by soft rot fungi and other soil-inhabiting microorganisms. Changes in the chemical composition of untreated wood and acetylated wood following exposure to fungal attack were examined by wet chemical analysis, as well as FT-IR and CP/MAS 13C-NMR spectral methods.
H Militz, Dong-won Son, L Gómez-Hernández, R Sierra-Alvarez


A method and apparatus for rapid assessment of termite barriers.
2007 - IRG/WP 07-20366
This paper describes an apparatus for rapid assessment of barriers to subterranean termite foraging. The method and apparatus arose from the development of a novel physical termite barrier. The barrier had to be flexible, resilient, able to be applied as a liquid and be neither toxic nor repellent. This posed a special problem as existing laboratory assessment techniques did not offer a sufficient incentive for termites to challenge the test samples. Previously developed laboratory methods of exposing a candidate barrier material provided either (i) only chance and incidental contact with the termites with termite damage restricted to the edges or (ii) an unnatural situation where termites were attempting escape. A method was required that would reliably provide sustained contact and challenge the termites to penetrate the test sample. Observation of termite attack on structures provided a means to use the termites’ own foraging strategy to situate the barrier sample in a location of maximum termite activity. A high density of termites in a restricted space has feeding activity focussed so as to ensure sustained contact and challenge for the material under test. The focus of termite attention is achieved by providing the termites with a minimally sized timber dowel as a food source. The dowel is hollow which leads the termites to concentrate their feeding activity within its confines. The test sample is held at the distal end of the dowel, in a separate container.
D McG Ewart


Effect of Cinnamomum kanehirae Extractives on the Compositions of the Fermentation Broth of Antrodia cinnamomea
2007 - IRG/WP 07-10632
The fruiting body of Antrodia cinnamomea, called niu-chang-chih, is well known and highly prized in Taiwan as a folk medicine. This fungus is endemic to Taiwan and the growth of which is restricted to the inner heartwood cavities of another endemic tree species, Cinnamomum kanehirae. The fungal basidiomes have been used for treating food and drug poisoning, diarrhea, abdominal pain, hypertension, itchy skin and cancer. The purpose of this study was to investigate the effect of C. kanekirae extractives on the fungal mycelium production and the spore germination. The heartwood was extracted using 70% ethanol, and then liquid-liquid partitions using n-hexane, ethyl acetate, n-butanol and distilled water were carried out respectively. The effects of treating the fermentation broths with C. kanehirae extractives on the fungal biomass, antioxidant scavenging activity using 1, 1-diphyenyl-2-picrylhydrazyl (DPPH) were examined, and the compositions of the fermentation broth were monitored using high-performance liquid chromatography analysis. The results indicate that C. kanehirae extractives treated fungal broths had higher growth promotional effect on their biomass then that of the control (0.0313 g). The n-hexane soluable fraction treated mycelia showed the greatest dry mass (0.0480 g), followed by ethyl acetate soluable fraction (0.0333 g). The addition of crude extract increased the spore germination activity from 8.1 x 106 cfu/ml to 1.1 x 107 cfu/ml. The n-butanol soluble fraction showed the best spore germination activity of 1.3 x 107 cfu/ml. The active fungal ingredient, dehydroeburicoic acid, was found to increase with the addition of C. kanehirae extractive fractions according to the HPLC analysis. The C. kanehirae extractives were effective DPPH free radical scavengers which masked the antioxidant effect of the fungal broth.
Ruo-Yun Yeh, Yuan-Min Shen , Shang-Tzen Chang


Ecotoxicity of furfurylated wood – Effect of leachate on aquatic bacteria
2008 - IRG/WP 08-50250
Environmental concern regarding the use of toxic preservatives such as CCA (chromated copper arsenate) has been put forward. In the EU, USA and Japan, CCA is now phased out for residential use and for use in water contact. Several ecotoxicological studies of wood treated with conventional preservatives were carried out in the late 1990s. In these studies it was concluded that the main impact is to water and thereby to aquatic organisms. Today, alternatives to conventional preservation, marketed as “environmentally friendly” or “non-toxic” are emerging on the market. Examples of such alternatives are modified wood, e.g. thermally modified, furfurylated and acetylated wood. So far, not enough ecotoxicological studies have been done on these new methods. In the presented study the Microtox assay with the marine bacterium Vibrio fischeri are used as a screening method. Vibrio fischeri were exposed to water leachates from furfurylated wood using two different leaching procedures. The results from the OECD 2 standard test show that Kebony 2 (one of the commercially used furfurylation processes) treated Scots pine have a lower toxicity than all the other samples at all points and that it is the lowest at every point for Radiata pine as well. The explanation might be that there is an immobilization of slightly toxic wood extractives by incorporation in the furan polymer. The lower toxicity for Kebony 2 than for Kebony 1 might be a result of the intermediate vacuum drying step for Kebony 2 that leads to a more efficient curing/polymerisation and less hydrophobic oligomers of a type that may be slightly toxic.
A Pilgård, M Westin


A rapid microscale assay for determining growth of wood inhabiting fungi against Lactobacillus metabolites
2009 - IRG/WP 09-20412
Lactobacillus sp. are well known for their ability to produce secondary metabolites with potent inhibitory activity against a wide range of bacterial species and there is increasing evidence to support their antifungal activity. These metabolites are often screened in laboratories using microscale 96-well plate optical density assays. The objective of this study was to develop an optical density assay using 96-well microplates to assess the activity of Lactobacillus metabolites against wood decay fungi. The method was also compared with the standard solid agar growth-rate assay. Furthermore, various nutrient media were used to optimise the growth of Lactobacillus and decay fungi. The microplate assay showed comparable results to the commonly used solid agar growth-rate assay. The effect of secondary metabolites of Lactobacillus grown on MRS media was evident against decay fungi with variance in tolerance level.
D O’Callahan, T Singh, I McDonald


Methods for Studying Penetration Depth of Wood Protection Products
2010 - IRG/WP 10-20432
EN 152 is an accepted standard in Europe for measuring how deep a wood protection product penetrates into the surface of treated pine wood. The method has provided consumers with a wide assortment of products that meet the specifications outlined in the standard. Because the test takes 8 or more months to carry out, artificial ageing procedures have evolved in order to standardize and speed up the procedure. Small changes in a formulation will often change a products physical parameters and especially its ability to penetrate into wood. It is therefore desirable to develop a method that can measure changes in a product’s penetrability quickly and accurately. A method is described where wood cores are drilled from treated wood, then sliced in 100 µm thick discs. Discs are then placed on nutrient agar plates seeded with conidia from Aspergillus niger. Plates are incubated for 24 hours and zones of inhibition are measured. It is believed that if a fungus is growing on the disc the biocide level will not exceed that of the fungus minimum inhibition concentration (MIC). In water based acrylic systems penetration depths are often less than one mm and it can impact the performance of a product if that changes. The procedure described in this study can show if penetration of a preservative product has been increased or reduced in as little as 24 hours.
K Hansen, L Sites, D D Nicholas


Comparison of gauge and assay retention in crossties treated with copper naphthenate
2014 - IRG/WP 14-40667
Creosote has been the most widely used preservative for wooden railroad crossties or sleepers for over 100 years. Alternative preservatives such as copper naphthenate (CuN) have been shown to provide equivalent performance against decay fungi and wood destroying insects; however, the use and specification of CuN involves an education process for treaters and railroad customers alike. One difference between the two preservatives is use of a diluent or carrier oil with CuN, where both copper and oil retention become treating factors. Another is the ability to easily determine copper concentration in various zones throughout the interior of ties treated with CuN. Assay retention and other results-based specifications may be somewhat new concepts to tie treaters accustomed to measuring gauge retention based solely on volumetric or gravimetric uptake of creosote or creosote solutions. The objective of this study is to compare preservative retention in oak/hickory and mixed hardwood crossties treated with CuN in diesel oil solutions when measured by gauge and assay, and to determine if minimum copper retentions are achieved even when gauge retention (net solution uptake) appears deficient. Gauge and assay retention was measured from 272 commercial hardwood tie charges treated with CuN solutions, and copper retention was determined in core borings at various assay zones. The data confirm that adequate copper retention is achieved in both oak and mixed hardwood charges even when at relatively low solution retention levels, either because of refractory species or low copper concentration in the treating solution. Copper retentions measured by assay exceeded by 26-67% the values for gauge retention estimated from solution uptake, in part due to selective adsorption of copper.
J Brient, H Tomlinson, J Hughes


Wood Protection Using Nano Metal Oxides in Propylene Glycol
2022 - IRG/WP 22-30760
Metals and metal oxides are known to have properties that can protect wood from degradation. Nanoparticles, due to its unique physical and chemical properties can enhance the protection to a much greater extent. Major constraints in dealing with nanoparticle dispersion can only be resolved by identifying a proper dispersive medium. Studies were carried out by preparing nanodispersion of four metal oxides (ZnO, CuO, CeO2 and TiO2) in propylene glycol using ultrasonication without addition of any surfactant or dispersant. The process yielded stable dispersions without agglomeration or settling of nanoparticles and can be stored for longer durations. CuO dispersion showed less stability though complete settling of CuO nanoparticles was not observed. Antifungal assay as plate test show that 0.01 to 0.05% of nanoparticle dispersions can prevent white-rot and brown-rot fungal growth. Fungal resistance tests using nanodispersion treated wood specimens shows that nano-ZnO dispersion in propylene glycol inhibited decay more effectively than commercially available ZnO aqueous dispersion. CuO was more efficient in preventing decay than ZnO dispersion of same concentration. Nanodispersion provided termite resistance and 5% CuO treated specimens prolonged service life of treated wood specimens to more than one year. UV stability of wood surfaces coated with nanodispersion of ZnO, CeO2 and TiO2 was evaluated under laboratory conditions in an accelerated weathering tester. Increase in concentration of nanoparticle from 1% to 2.5% significantly enhanced UV resistance. However, increase in nanoparticle concentration reduced transparency particularly in ZnO and TiO2. Results indicate that propylene glycol can be considered as a viable dispersant to prepare nanoparticle dispersions, as it provides stability to the dispersion without affecting the photo-screening effect of nano metal oxides. The results of the study will help in developing a nano-based wood preservative formulation with increased antifungal and anti-termite properties.
S Nair, G B Nagarajappa, K K Pandey