Treated Wood Specimens Research Articles

Durability assessment of one-component polyurethane adhesives for bonding of preservative treated wood subject to artificial ageing

Advancements in the use and applications of engineered wood products is receiving much interest in the construction industry. This is because wood has highly credible characteristics in relation to sustainability. It acts as a carbon store and is a natural renewable material. However, achieving adequate durability requirements and ensuring satisfactory adhesive bondline integrity is fundamental for such engineered products particularly when subjected to an exposed exterior service class environment. Little information exists on the durability performance of preservative treated wood bonded using one-component polyurethanes (1C-PURs). This study therefore involved the accelerated ageing of two 1C-PUR adhesives for the bonding of untreated, copper chromate arsenic and micronised copper azole preservative treated wood of fast growing Radiata pine. The ageing involved both vacuum-pressure soak drying cycling and exposure to a constant long-term high temperature and humidity environment. Resorcinol formaldehyde bonded specimens and solid wood specimens were used as controls. The testing showed that the standard requirements for delamination were satisfied when bonding preservative treated wood with 1C-PUR adhesive. The shear strength of specimens bonded with 1C-PUR adhesive subjected to vacuum-pressure soak drying compared well to the performance of the controls. The predominant failure behaviour was wood failure. The shear strength of all bonded preservative treated wood specimens with both 1C-PUR and resorcinol formaldehyde which were exposed to a constant long-term high temperature and humidity environment demonstrated a general and comparable reduction in strength over time which was statistically significant. High wood failure percentages were recorded at the bond interface which indicated weakening of the wood adherend when subject to the ageing rather than weakening of the adhesive bond. Chemical analysis of bonded specimens after ageing demonstrated that no significant variations were experienced.

The effects of increasing preservative uptake by microwave pre-treatment on the microstructure and mechanical properties of Oriental spruce wood

ABSTRACT In the microwave (MW) pre-treatment process, a constant MW energy intensity of 2158 MJ/m3 was applied by using 925 W (3700 sec.), 1295 W (2640 sec.) and 1850 W (1850 sec.) powers. Tanalith-E preservative material was used to determine the increase in impregnability of MW pre-treated wood. The mechanical properties of the treated wood specimens were tested to determine the degradation caused by exposure to the MW radiation. Additionally, scanning electron microscope (SEM) was used to determine the changes in wood microstructure with the effect of microwave pre-treatment. According to the impregnations, the average preservative material retention rates increased 62% for the specimens with MW groups, compared to the reference specimens. The mechanical properties of the MW pre-treated specimens decreased by (average) 5% in compression strength, 12% in the bending strength and 16% in the modulus of elasticity. SEM observations of the reference specimens showed that there were many aspirated bordered pits before MW pre-treatment. After the MW pre-treatment, parts of the pit membranes were damaged. The torus ruptured and cracked, while the structure of the micro-fibrils on the margo remained intact. In the observations of the intercellular microstructure of wood, it was observed that micro cracks with a width of 1–10 μm were formed.

Evaluation of water related properties of birch wood products modified with different molecular weight phenol-formaldehyde oligomers

Abstract This study investigated the effect of phenol-formaldehyde (PF) resin treatment on the dimensional stability of birch solid wood and plywood. Therefore, three different low molecular weight PF resins with average molecular weights (M w ) of 292, 528, and 884 g/mol were synthesized and used for silver birch (Betula pendula) solid wood (20 × 20 × 20 mm3) and veneer (100 × 100 × 1.4 and 300 × 300 × 1.4 mm3) impregnation to produce plywood. The weight percent gain (WPG) and bulking after curing of resin treated wood specimens were determined. The leaching was performed to evaluate the PF resin fixation stability. All tested resins at all concentrations were similarly fixed in wood blocks after the leaching (1.5–2.0% WPG loss). The dimensional stability of birch wood after treatment with all tested PF resins was significantly improved. The anti-swelling efficiency (ASE) of birch wood blocks treated with PF resins after seven water soaking-drying cycles was in the range of 39–53%, 46–65% and 49–65% using 10, 15 and 20% solution concentrations, respectively. Whereas, the ASE of plywood obtained from veneers treated with 10% of PF solution was improved by 6–20%. The equilibrium moisture content (EMC) and volumetric swelling (VS) of PF treated plywood at 98% of relative humidity (RH) decreased significantly. All PF resin treated plywood surfaces were more hydrophobic compared to untreated plywood.

Preservative effect of Tetraclinis articulata and Cedrus atlantica wood extractives against fungal decay

Testing environmentaly-friendly plant essential oils for their ability to protect non-durable wood against wood decay fungi is a research topic of current interest. In this study, wood preservative potential of extracts from the wood of the durable species, Tetraclinis articulata and Cedrus atlantica were assessed on non-durable maritime pine sapwood, Pinus pinaster var atlantica, after exposure to three wood decay fungi, according to the EN 113 Standard. Significant differences were observed between treatment effects of these extracts, between fungal decay levels and between oils concentrations. Overall, mean mass losses of treated wood specimens were above 8%. T. articulata root burl extract gave the best protection level for this type of wood against Gleophyllum trabeum and Rhodonia placenta but only at test concentrations above 0.1%v/v. However, efficacy levels of both extracts’ treatments, applied at the tested concentrations, were judged insufficient on the basis of the NF EN 113 standard used.

Effects of heat treatment on the behavior of teak wood adherends bonded joints

The main aim of this work is to investigate the effect of heat treatment on the teak wood adherend bonded joints. Indian teak wood samples were kept in an oven at 150 °C for 2 h for the heat treatment process. The surface roughness values of the wood adherend before and after the heat treatment process were measured using a surface profilometer. Wettability of un-treated and heat-treated teak wood samples was determined with the contact angle measurements by using the sessile drop method. Single strap joints with un-treated and heat treated wood specimens were tested at ambient temperature. The results show that, there is a clear dependency observed in between the heat treatment and the surface roughness of the wood adherends. Wettability of teak wood adherend surface is degraded after the heat treatment process. An adverse effect of heat treatment of wood adherend on the bonding strength was observed, but the surface roughness was improved.

Mold Resistance of Nano and Micronized Particles-Treated Wood After Artificial Weathering Process

Wood and wood based materials under outdoor conditions may lose their appearance and performance properties by time. Color differences, cracks, rough surface may occur within a few years in unprotected wood. These undesired formations could be avoided by technical applications such as coatings on wooden surfaces by paints and varnish since such coating materials include special additives in their formulations such as UV absorbents, pigments, etc. Novel systems with nano or micronized particles may have superior properties when compared to conventional wood preservatives. In this study, we compared nano-scale, micro-scale and common wood preservatives in treated wood in terms of their effectiveness against mold fungi before and after artificial weathering process. Accelerated weathering tests of the test specimens were performed in a Xenon arc radiation cabinet with water spraying property. Artificially weathered and treated wood specimens were evaluated for resistance to mold fungi according to the ASTM D4445. General mold score results collected before and after artificial weathering process showed that CCA and MCQ-treated specimens had the best performance properties; however, nano zinc oxide-treated wood specimens had the weakest performance against mold fungi.

Water Related Properties of Birch Wood Modified with Phenol-Formaldehyde (PF) Resins

In this study, Silver birch (Betula pendula) wood veneers and solid wood blocks were treated with commercial phenol-formaldehyde (PF) resin water solutions. Birch veneers and solid wood blocks of different size were impregnated with PF resin solutions in water with concentrations of 10, 20 and 30 wt%. The weight percent gain (WPG) and bulking after drying and curing of resin treated wood specimens were determined to evaluate the impact of specimen sizes and density. The leaching procedure according to EN 84 was performed to evaluate the PF resin fixation stability. The anti-swelling efficiency (ASE) of untreated and treated specimens during seven soaking-drying cycles was examined. Higher WPG values were obtained for specimens with lower density, but no correlation was found between the specimen size and WPG. The WPG of veneers and solid wood was 8.7 - 17.7% and 8.5 - 24.4%, respectively. The ASE of wood blocks treated with PF resins after the 1st cycle was in the range of 37 - 51% depending on the resin loading in the wood. However, the ASE values decreased after every next soaking-drying cycle, reaching 33 - 48% after the 7th cycle. After leaching, the WPG of specimens decreased by 2.3 - 3.0%.

Decay resistance of polymerized ionic liquid-modified woods

A functional ionic liquid 1-butyl-3-vinylimidazolium iodide ([BuVyIm]I) was synthesized, and it exhibited the features of both decay resistance and leaching resistance after in-situ polymerization within wood. Treated wood specimens of Cryptomeria japonica were evaluated in this preliminary study using leaching tests with distilled water and decay tests for 12 weeks with brown rot fungi Fomitopsis palustris. The [BuVyIm]I polymerized by 100 kGy 60Co gamma irradiation was retained in wood after 10 wash and dry cycles, whereas nearly all of the [BuVyIm]I was washed out in the cases of 10 kGy and no irradiation. The decay testing of these specimens showed that sapwood had a different decay resistance depending on the strength of gamma irradiation used, whereas the treated heartwood did not support fungal growth. The results of this study imply that [BuVyIm]I polymerized by 100 kGy gamma irradiation have potential for wood preservation.

Biological performance, water absorption, and swelling of wood treated with nano-particles combined with the application of Paraloid B72®

We evaluated fungal decay and mold resistance, leaching, and water absorption of nano-compounds and Paraloid B72® (PB72) in treated wood specimens to develop new methods of consolidation by combining nano-particles and consolidants. Scots pine wood specimens were treated with dispersions of nano-CuO, nano-ZnO, nano-B2O3, nano-TiO2, and nano-CeO2. PB72 treatments of nano-particle-treated wood specimens were then carried out by either vacuum or immersion for 24 h. Previously, decayed wood specimens were also consolidated with the nano-compounds and PB72. PB72 treatments reduced element release from treated wood specimens. Nearly all nano-compounds + PB72 treatments increased the biological performance of treated wood specimens against decay fungi tested. PB72-only treated wood specimens had the highest weight losses in decay tests. No improvements were obtained in mold resistance tests when the nano-compounds and PB72 were combined. In nano-compound-only treatments, unleached specimens showed slightly lower water absorption values compared to untreated control specimens. Incorporation of PB72 into nano-compound-treated wood specimens resulted in considerably lower water absorption and volumetric swell. In previously decayed specimens treated with the nano-compounds and PB72 solution, water absorption after 2-h immersion declined compared to control specimens.

Detection of outdoor mould staining as biofinish on oil treated wood

Stains on wood are often unwanted in outdoor applications, dark stain formation however is essential to the development of a new protective, self-healing and decorative biotreatment for wood. The biotreatment is based on the formation of surface covering mould staining on linseed oil treated pine sapwood during outdoor exposure. This specific stain formation is called biofinish and an assessment method is proposed in this study. Analysis of the visual stain coverage and quantification of the darkness generated useful input for the detection of biofinishes. Analysis of the microbial composition of a biofinish by PCR amplification and (Sanger) sequencing of fungal DNA sequences was appropriate for identification of Aureobasidium, as the dominant genus in several biofinishes, however our results indicate, that a more in depth, next generation sequencing method is preferred for a more elaborate biofinish assessment method. With the basic assessment method, biofinish formation was determined for oil treated wood specimens exposed outdoors in the Netherlands and some selected sites outside the Netherlands. Biofinish formation was demonstrated to be reproducible for pine sapwood, which was treated with raw linseed oil and exposed in the Netherlands. Furthermore olive oil is discovered in this study as a supportive factor for biofinish formation, regardless of the wood type, whereas biofinish formation was not detected on wood treated with stand linseed oil.

Reaction to fire and water vapour resistance performance of treated wood specimens containing TiO2and clay nanoparticles

SUMMARYThe effect of TiO2and/or clay nanoparticles on water vapour permeability and the reaction to fire performance of coated and impregnated spruce wood were studied. Water vapour permeability properties were used to assess the moisture transfer properties and durability of the specimens using the cup test. The reaction to the early stage fire development properties of the specimens was analysed using a small scale cone calorimeter test. Comparisons between the different treated and untreated specimens on the moisture and reaction to fire performances were performed. The results revealed poor reaction to fire and water vapour resistance of specimens treated with TiO2and/or clay nanoparticles containing treatments. Copyright © 2013 John Wiley & Sons, Ltd.

Antifungal properties of some plant extracts used as wood preservatives

This study evaluated antifungal resistance of some commercial and environmentally friendly plant extracts. Four different concentrations of mimosa (Acacia mollissima), quebracho (Schinopsis lorentzii) and pine (Pinus brutia) bark extracts known with their high condense tannin amounts were used to impregnate Scotch pine (Pinus sylvestris L.), beech (Fagus orientalis L.) and poplar (Populus tremula) wood specimens. Extract treated wood specimens were tested against two types of white rot fungi (Trametes versicolor and Pleurotus ostreatus) and two types of brown rot fungi (Fomitopsis palustris and Gloeophyllum trabeum) for 16 weeks. The lowest mass loss rates were recorded for mimosa and quebracho extract treated wood blocks at the 9% and 12% concentration levels against both white and brown rot fungi. Pine bark extract, on the other hand, seemed to be ineffective against all fungi species tested even at the highest concentration level (12%). The current study suggests that commercial mimosa and quebracho extracts can be utilized as alternative wood preservative chemicals against common wood decay fungi in indoor applications.

Resistance of smoked wood to subterranean and dry-wood termite attack

Specimens from Sengon (Paraserianthes falcataria), Sugi (Cryptomeria japonica), and Pulai (Alstonia sp.) trees were exposed for 3, 8, or 15 days to the smoke generated during Mangium wood (Acacia mangium) pyrolysis, and their resistance to termite biodeterioration was compared to that of polystyrene-treated or untreated woods. All treated-wood specimens were exposed to subterranean termites (Coptotermes curvignathus Holmgren) and dry-wood termites (Cryptotermes cynocephalus Light) under laboratory conditions. The results showed that: (1) All three untreated woods were classified as class V (or very poorly resistant) to subterranean termite attack. On the other hand untreated-wood specimens of Pulai and Sugi tree were classified as class IV (or poorly resistant) and specimens of Sengon tree as class III (or moderately resistant) to dry-wood termites, based on the national Indonesian standard; (2) for all three wood species, 3-day exposure to Mangium wood smoke increased their resistance to class I (or very resistant) to subterranean termite attack; and (3) smoke treatment for 3 days for Sengon and Pulai wood specimens, and 15 days for Sugi wood specimens was required to increase their resistance to dry-wood termite attack to class I, which is the resistance level characterizing polystyrene-treated woods for all three species.

Preliminary evaluation of storax and its constituents: Fungal decay, mold and termite resistance

Essential oils and their derivatives might be one of the promising preserving agents to prevent fungal decay and termite/insect attack in wood since such compounds have a long history of safe usage as antimicrobial agents in various industries. Considerable research has focused on utilizing bioactive essential oils and wood extractives based on green technologies to develop environmentally friendly wood preservatives. This study evaluated biological activities of storax from Liquidambar orientalis tree, some storax constituents and commercial styrax against wood-decaying fungi, mold fungi, and termites in laboratory conditions. Scots pine sapwood specimens were treated with various concentrations of styrax, storax and storax constituents i.e. cinnamyl acetate, cinnamyl alcohol and ethyl cinnamate. Treated specimens were subjected to leaching followed by soil block decay tests using two brown rot and two white rot fungi. Specimens were also subjected to two different laboratory termite resistance tests based on the standards methods by the American Society for Testing and Materials (ASTM) and Japanese Industrial Standards (JIS). Inhibitory effects of the compounds were evaluated in vitro against Basidiomycetes, mold, and staining fungi. Treated wood specimens were also tested for mold growth. The storax constituents, storax and styrax did not inhibit fungal decay by the brown rot fungi. The constituents and storax-treated specimens resulted in mostly “moderate resistance” to fungal decay by the white rot fungi based on the ASTM D2017 classification. Styrax only was effective against the Basidiomycetes fungi in vitro tests; however, the mold and staining fungi tested were not completely inhibited. Natural storax at the concentration level of 0.5% inhibited all fungi except Trametes versicolor and Ceratocystis pilifera. Cinnamyl alcohol inhibited fungal growth with the exception of Aspergillus niger. In mold tests, complete inhibition was not observed for any of the test fungi; however, cinnamyl alcohol reduced mold growth considerably on treated wood specimens. Cinnamyl alcohol was also effective against termites in unleached specimens; however, styrax and natural storax at the concentration level of 10% reduced wood consumption in treated specimens.

EFFECTS OF LEACHING MEDIUM ON LEACHABILITY OF WOOD PRESERVING N'N-HYDROXYNAPTHALIMIDE (NHA)

Laboratory leaching test procedures usually call for the use of distilled or deionized water; however, treated wood is generally exposed to different types of water, soil, and weather conditions. Thus, factors such as salinity, hardness, pH, temperature etc. might be important in the release of different amounts of biocide compounds. This study evaluates the release of the sodium salt of the calcium precipitating and wood preserving agent N’N-hydroxynapthalimide (NHA) from treated wood specimens exposed to different types of leaching media. Scots pine wood specimens were treated with NHA at three different solution strengths. Treated specimens were then leached with distilled water, tap water, rain water, synthetic sea water, natural sparkling water, or 1% CaCO3 solutions for 2 weeks. Leaching with higher ion concentrations reduced NHA losses from the specimens in comparison with that of distilled water and rain water leaching trials. Microscopic evaluations were in good accordance with the results from leaching trials, revealing NHA precipitation onto the tori of pit elements and tracheids. In distilled water and rain water leaching trials, less NHA precipitation on to the tori of pit membranes and tracheid surfaces was observed, whilst the specimens leached with tap water, 1% CaCO3, sea water, and sparkling water showed higher NHA precipitations on the cell elements. We conclude that the leaching of NHA from treated wood can be decreased by precipitation with ions coming from tap water, sea water, sparkling water, and 1% CaCO3 solutions as leaching media rather than distilled water or rain water with no or much less ion composition.

Effect of novel consolidants on mechanical and absorption properties of deteriorated wood by insect attack

The influence of chemical treatments based on novel organic products on the consolidation of deteriorated wood by insect attack was evaluated on two hardwoods and one softwood: fir (Abies alba), beech (Fagus sylvatica) and deciduous oak (Quercus sp.). Degraded and intact specimens of the three wood species were impregnated with two different chemical treatments aimed to verify the potential synergic action of the novel products on wood. Then, the specimens were subjected to bending, compression parallel to the grain, impact, hardness and water absorption tests. Untreated specimens of the same botanical species, both degraded and non-degraded, were examined for comparison purposes. The experimental results showed a different effectiveness of the proposed chemical treatments to improve the mechanical and absorption properties of degraded wood. The most effective treatment was the one assuming the concurrent use of the studied novel consolidants. The species more susceptible of the enhancement in mechanical properties were fir and beech. The observed differentiations were most likely caused by the different structure of the botanical species considered, leading to a consequent different product penetration in the wood structure. The dimensional stability in terms of water repellent and antiswelling efficiency, after a three-month immersion in deionized water, was found to improve in all the treated wood specimens. Overall, experimental results showed that the impact of the chemical treatments was higher on degraded samples than on intact ones.

Efficacy of tar oil recovered during slow pyrolysis of macadamia nut shells

Decay and termite resistance of wood treated with tar oil obtained from a commercial pyrolysis process of macadamia nut shells was evaluated. Vacuum-treated pinewood specimens were subjected to two brown- and two white-rot fungi based on the soil-block test method specified by the American Wood Protection Association after a 10-day-leaching process. Treated specimens were also subjected to the subterranean termite attack according to Japanese Industrial Standards (JIS) for 3 weeks under laboratory conditions. In the study, growth inhibition of selected fungi with the tar oil was also tested in vitro. Treated wood specimens at a retention level of 460 kg m−3 showed good protection against all the fungi tested. Mass losses in leached specimens were less than those observed in unleached specimens. Similar results were seen when the specimens were subjected to termite attack. Inhibition tests showed that higher concentrations of the tar oil are critical for inhibition of the brown-rot fungi compared to the concentrations required to impede the white-rot and sap-staining fungi tested.

Durabilty of 25 Local Specific Wood Species from Java Preserved With CCB Against Marine Borers Attack

This study was conducted to provide basis information of the 25 local specific wood species indigenous from Java treated by copper bichromated boron (CCB). The full-cell process for 2 hours and 150 psi during the pressure-keeping period was employed. The IUFRO method was applied for the determination of wood treatability class. The treated and untreated wood specimens were tied together using plastic cord, arranged into a raft like assembly, and then exposed for 3, 6, and 12 months to the brackish water situated at Rambut Island’s coastal area. The Nordic Wood Preservation Council (NWPC) standard No.1.4.2.2/75 was used to determine the intensity of marine borer infestation. The results revealed that 19 out of those 25 species were classified as easy to be preser ved, four species as moderate, and the remaining two were difficult to be preser ved. Those 19 species, i.e. T amarin d u s indica L., D i plodiscus sp., F icu s variegate R .Br., Ehretia acuminata R .Br., M e li oco p e l u n u -a nk e n d a (Gaertn) T.G. Hartley, C o l o n a javanica B.L., P ou teria d u c l i t a n Bachni., S tercularia oblongata R .Br., F icu s vasculosa Wall ex Miq., C a l l o p h y ll u m g r an d i florum JJS., T u r pi n i a sphaerocarpa Hassk., N e o l i tse a triplinervia Merr., A c e r niveum Bl., Sl oa ne a sigun Szysz., Castanopsis acuminatissima A.DC . , C i nnamomum iners Reinw. Ex Blume., L it s e a angulata Bl., F icu s nervosa Heyne., and H or sfi eldia glabra Warb . were more permeable implying that the CCB retention and penetration were greater and deeper. H y m e n e a e ca r b o r i l . L., L i t s e a od o r i f e r a Val., G i ronniera s u b a squ a li s Planch., and L ind e r a p o l y a n t h a Boerl. were moderately permeable. Castanopsis tunggurut A.DC . and A z a d i r a ch ta indica Juss. were the least permeable judging that the CCB retention and penetration were lowest and shallowest. The treated wood specimens in this regard were able to prevent marine borers attack. Meanwhile, the untreated specimens were susceptible to marine borers attack, except A z a d i r a ch t a indica . The attacking borers consecutively are M a r t e s i a s t r i a t a Linne that belongs to the Pholadidae family ; and T e r e d o b ar t s c h i Clapp., D i c ya thifer manni Wright., and B a n k i a cieba Clench. to the Terdinidae family.

Evaluation of decay and termite resistance of wood treated with copper in combination with boron and N′-N-(1, 8-naphthalyl) hydroxylamine (NHA-Na)

This study evaluated the relative ability of various combinations of copper sulfate with either boric acid or calcium-precipitating agent, N′-N-(1, 8-naphthalyl) hydroxylamine (NHA-Na), to inhibit fungal degradation and attack by Formosan subterranean termites ( Coptotermes formosanus Shiraki). Wood specimens were treated with either 1%, 0.5%, or 0.1% concentrations of copper sulfate, boric acid, NHA-Na, copper sulfate + boric acid, or copper sulfate + NHA-Na mixtures. Treated specimens were subjected to laboratory decay-resistance tests by using petri dishes inoculated with the Basidiomycetes fungi Tyromyces palustris and Trametes versicolor for 12 weeks. Treated wood specimens were also subjected to termite-resistance tests under laboratory conditions. Increased efficacy of copper sulfate against the brown-rot fungus T. palustris was observed when either boric acid or NHA-Na was added. The most effective treatments against the fungi tested were NHA-Na only treatments at 1% and 0.5% concentration levels. Boric acid treatments were not able to protect wood against decay after leaching because of excessive leaching of boron. Similar results were obtained in termite-resistance tests in comparison with decay-resistance tests. These results indicate that the efficacy of the treatments in preventing fungal and termite attack is a function of the type of preservative.

Do the unique properties of nanometals affect leachability or efficacy against fungi and termites?

Nanotechnology has the potential to affect the field of wood preservation through the creation of new and unique metal biocides with improved properties. This study evaluated leachability and efficacy of southern yellow pine wood treated with copper, zinc, or boron nanoparticles against mould fungi, decay fungi, and Eastern subterranean termites. Results showed that nanocopper with and without surfactant, nanozinc, and nanozinc plus silver with surfactant resisted leaching compared with metal oxide controls. Nearly all nanoboron and boric acid was released from the treated wood specimens during leaching. Mould fungi were moderately inhibited by nanozinc oxide with surfactant, but the other nanometal preparations did not significantly inhibit mould fungi. Mass loss from Gloeophyllum trabeum was significantly inhibited by all copper preparations, while Antrodia sp. was not inhibited by nanometal treatments. Nanometals imparted high resistance in southern yellow pine to the white-rot fungus, Trametes versicolor. Unleached specimens treated with nanoboron or nanozinc plus surfactant caused 100% and 31% mortality, respectively. All specimens treated with nanozinc or nanozinc plus silver inhibited termite feeding, but the copper treatments were less effective against termites. Nanozinc possessed the most favorable properties: leach resistance, termite mortality, and inhibition of termite feeding and decay by the white-rot fungus.