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Principles and procedure of the planeing test
1981 - IRG/WP 2162
Small end-sealed samples of pine-sapwood (1.5 x 2.5 x 5 cm³) are treated by brushing and afterwards different parts of the treated surface are removed. The remaining part of the sample is tested against either insects or fungi. If no attack occurs sufficient amounts of biocides have been penetrated at least beyond the zone which has been removed. In spite of some problems the test seems the only suitable method, to evaluate organic solvent preservatives, mainly those containing resins, for simple treating methods.
H Willeitner, M Gersonde


Biological resistance of wood treated with waterbased resins and drying oils in a mini-block test
1998 - IRG/WP 98-40107
In recent years it was found that the resistance of wood against fungal degradation could be increased by impregnation with an etherificated melamine formaldehyde resin. Using this resin as a reference, a waterbased fatty acid modificated alkyd-resin and two drying-oils were assessed for their biological performance in a mini-block laboratory test. Although drying-oils, like linseed-oil, are often used as a binder in paints, little information is available about the resistance of wood impregnated with these oils against wood destroying basidiomycetes. The fungi used in this test were the brown rot fungi Coniophora puteana, Gloeophyllum trabeum and the white rot fungus Trametes versicolor. The results showed considerable less mass loss of the melamine resin and the drying oils treated wood compared to the untreated Scots pine (Pinus sylvestris) controls. The mass loss of the oil treated specimens, however, was obviously depending on the fungus and the applied treatment and the wood species.
M Sailer, A O Rapp, R-D Peek


Leaching of components from water-borne paints and fungitoxic effects
1995 - IRG/WP 95-20062
Water-borne model paints, acrylics and alkyd emulsion paints, of known composition were leached according to a procedure modified in accordance with ASTM 6271.1. The effectiveness of fungicidal compounds in the painted specimens before and after leaching was evaluated with a biotest in which Penicillium brevicompactum was used as a test fungus. The leaching of the fungicide Troysan Polyphase according to the biotest varied to a high extent depending on differences in paint composition. Fungicide efficiency in relation to paint formulation and fungicide mobility in a paint film is briefly discussed.
J Bjurman


Time dependent over-uptake of etherificated melamine resins
1998 - IRG/WP 98-40109
Waterbased methanol-etherificated melamine-formaldehyde resins can increase the fungal resistance of the treated wood though they are known to be non-toxic. Therefore melamine-resins are at the present an object of research activities of European projects and of some companies. The paper highlights the importance of quoting the duration of the diffusion when immersed in the treating solution, as major differences in the effectiveness against fungal attack can be obtained by extending the diffusion period. This paper also critically reviews the practice of referring the concentration of the solutions used for impregnation to a fixed solids content of this type of resins.
D Lukowsky, R-D Peek


Analysis of organotin fungicides in wood preservative solutions and double-vacuum treated wood
1983 - IRG/WP 3250
A new analytical method using high-performance thin-layer chromatography (HPTLC), for the assay of organotin compounds in preservative-treated wood, is presented. The organotin compounds are extracted from the ground wood sample with a mixture of hydrochloric acid and ethanol. After HPTLC-separation, exposure of the thin-layer plate to ultraviolet light, and dipping of the plate into a 0.1% pyrocatechol-violet solution, the different organotin compounds are quantitated using a scanning densitometer.
W Hintze, S V Ohlsson


Termiticidal chemicals derived from tropical tree resins
1991 - IRG/WP 1477
To test the hypothesis that defensive chemicals protect tropical primary forest trees against biological attack, a bioassay and fractionation program was conducted in Indonesia. Fresh dipterocarp resins were fed in no-choice tests to Neotermes dalbergiae termites on 4.5 cm filter papers, or tested for inhibition of fungal growth. Fractionation of biologically active resins via flash column chromatography, followed by subsequent bioassay and analytical chemical studies, revealed that several sesquiterpene compounds inhibited fungal growth and killed 50% of test termites in 3-7 days. Toxic fractions contained caryophyllene, caryophyllene oxide, alloaromadendrene, and other compounds. From the relatively non-toxic a-gurjunene, novel termiticidal compounds were synthesized, indicating the potential for manufacture of insecticides from natural products.
A Messer, K McCormick, D Richardson, Sunjaya, H Hagedorn, J Meinwald


Improvement of some technological and biological properties of poplar wood by impregnation with aqueous macromolecular compounds
1992 - IRG/WP 92-3721
Poplars (Populus spp) belong to the most important tree species in afforestation programs of the Netherlands. Due to their rapid growth, the wood quality is usually low. Therefore, studies were performed to elucidate whether some technological properties and the resistance against fungal attack could be improved by impregnation with water-soluble resins. The results showed that swelling and shrinkage of poplar wood may considerably be reduced by a treatment with certain resins. The anti-shrink efficiency (ASE) strongly depends upon the resin type. An air-curing alkydresin based on polybutadiene and an air-curing acrylate modified alkydresin emulsion caused the best effects. Additions of wood preservatives to the resins further improved the ASE. Some disadvatages of the tested resins may be seen in their leachability with consequent loss of the dimension-stabilizing effects. The resins by themselves don't reveal fungistatic properties but an impregnation of poplar wood with these materials led in all cases to a better durability against Coniophora puteana and Coriolus versicolor. Leaching procedures influenced the durability in various ways. With resin/fungicide combinations, a good resistance against Coriolus versicolor could be reached even after leaching. SEM and EDXA methods were used to localize the resins in the cell walls and lumina and to detect the growth of mycelium in the specimens.
R D Peek, H Militz, J J Kettenis


Remedial treatments of glulam = diffusion of active ingredients through glue lines from solid wood diffusable preservatives
1996 - IRG/WP 96-30117
Diffusable preservatives are very suitable for use in remedial treatments of laminated beams in which too high moisture content involves the development of wood destroying fungi. The diffusion of active ingredients (boric acid, disodium octoborate, bifluoride) is well observed in solid wood but in a composite wood, the glue lines may appear not only as a barrier for the diffusion but also, may be mechanically affected by the diffused active ingredients. Shear tests were carried out on glulam specimens manufactured with different types of glues: resorcine (RF), ureaformaldehyde (UF), polyurethane (PUR) and polyvinylacetate (PVAc). Diffusion tests were also carried out in accelerated wetted glulam specimens with three diffusable solid preservatives differently exposed in the test samples. Results observed with boron compounds showed that their diffusion does not affect the mechanical resistance of the beams. In another hand, interesting results were obtained concerning the passage of boron and bifluoride through some types of glues. These results will contribute to the optimization of the remedial treatment of glulams.
D Dirol, S Mouras


Blue Stain Testing of Alkyd and Acrylic Stains
2003 - IRG/WP 03-20273
Resistance against blue stain of semi-transparent alkyd and acrylic stains was tested by both EN 152 and the so-called reverse exposure test methods. Comparison of the results, obtained by both methods was the most important aim of this study. As expected, performance of the water-borne acrylic paint was lower compared to protective effectiveness of the alkyd stain. This difference was even more pronounced when artificially accelerated aged samples were exposed. It seems that the reverse exposure method may give more distinctive results. In general, our results confirm previous literature reports on adequacy of the reverse test method for evaluation of blue stain resistance of surface finishes.
M Petric, M Pavlic, B Kricej, M Humar, F Pohleven


Durability of exterior natural wood finishes in Brazil
1985 - IRG/WP 3343
Wood finishes systems were evaluated in natural weathering conditions during 5 (five) years, over "Parana-pine" (Araucaria angustifolia). Test samples results show that: - Semitransparent wood preservative stains, based on polimerized linseed oil, provided very good protection to the wood, compared with the one based on alkyd varnish; - Solid color wood preservative stains provided good durability. However, film degrading process was identical to the one of conventional finishes; - Conventional paint and varnish showed decomposition caused by cracking, checking and flaking (scaling).
D R Macedo


Influence of different resin treatments on the dimension stability of wood
1997 - IRG/WP 97-40090
The dimension stability of wood is considered to be an important contribution to its durability and its performance in practice. A number of different treatments have been developed to improve the dimension stability of wood. One applied method is the treatment of wood with monomers or resins. The application of appropriate impregnation conditions seemed to be essential to enhance the efficiency of the treatment with water based resins. Therefore, wood samples of the three wood species Pinus sylvestris L., Pinus radiata D. Don. and Fagus sylvatica L. were impregnated with four different resin systems to evaluate the influence of different parameters on the anti-swelling efficiency (ASE). Variation in diffusion time, initial moisture content and resin concentration revealed considerable differences in retention of the resins and the ASE.
M Sailer, A O Rapp


Improvement of intrinsic properties of wood by chemical wood densification - Hydrophobic aspects and durability aspects
1999 - IRG/WP 99-40149
To improve the intrinsic properties of Scot pine wood ((1) hydrophobic surface and (2) durability), two ways of chemical modification have been tested. The first one is the chemical modification of hydroxyl groups by active substances like diisocyanate compounds with a copolymerization step. The second way is a densification by an impregnation of resins and a gamma polymerisation. This second way is described and discussed in this paper The measured parameters are (1) the hydrophobic properties of the surface based on permeability measurements and (2) the biological durability against wood decaying fungi and (3) the weathering behaviour. Significant results are presented and discussed to promote another way of wood preservation based on densification by resins.
G Labat, Q K Tran, I Le Bayon


Effect of some resin treatments on fungal degradation reactions
1999 - IRG/WP 99-10318
The effect of impregnation of wood with vegetable oil, tall oil and two water soluble on fungal degradation reactions was assessed by hydrolysis and enzyme activity measurements. The experiments were carried out by using isolated enzyme preparations and a living brown-rot fungus Poria placenta. The results indicate that the inhibitory effect of treatments was clearly directec towards the enzymatic hydrolyzability of the hemicellulosic and cellulosic components of wood cell wall. The water soluble resins and tall oil treatments significantly decreased the ability of isolated enzyme preparation to hydrolyse treated wood substrate. The inhibitory effect of these treatments was focused on the degardation of arabinoxylan and cellulose components of the wood cell wall. The vegetable oil treatment did not significantly prevent the enzymatic hydrolysis of wood substrate. The resin and tall oil treatments seemed also to interfere the production and/or mode of action of hydrolytic degradation pathway of living brown-rot fungus P. placenta.
A-C Ritschkoff, M Rättö, A J Nurmi, H Kokko, A O Rapp, H Militz


Influence of hydrophobic agents on the leachability of boron
1995 - IRG/WP 95-30064
Besides its low mammalian toxicity and a broad range of activity towards both fungi and insects, boron shows a high diffusibility, encouraging it to treat wood species of low permeability. However, its difussibility is at the same time responsible for a high risk of leaching, known since long. Nevertheless quantitative data about this process are only rarely available. Therefore, the leaching of boron under different conditions and possible means of hydrophobising boron treated wood in order to reduce leaching were investigated by laboratory and field tests. For this purpose paraffin and a primer have been applied to protect the inner surface and alkyd-resin and a varnish as surface coat. The results demonstrate that boron diffuses even at moisture contents below 20%. Thus leaching can not be affected by hydrophobic agents placed on the inner surface of wood because diffusion still takes place within the cell-wall. Surface coatings have some protective effect but only during a distinct periode which is depending on the thickness of the coat. With time leaching increases with increasing moisture content underneath this coat. The best way to prevent leaching is the logistical protection by storing and using boron-treated wood exclusively under cover. Only for a short periode, for example during construction, a surface protection with waxes or resins will be effective.
A Peylo, H Willeitner


New principles for the protection of wood: Impregnation with waterborne resins
1995 - IRG/WP 95-40047
The environmental impact of classical wood preservatives as well as the use of tropical wood species with high natural durability is regarded increasingly critically in the public. Therefore other partially new principles for the protection of wood, like chemical modification, or treatment with resins were examined especially in USA, Japan and in Europe with promising results predominantly in the lab scale. The work to be presented is focused on the feasibility to upgrade wood by a wide spectrum of water-borne resins under practical conditions of processing. The chemicals examined range from purely physically effective resins by hydrophobation and mechanical blockage up to such promising a chemical modification by their reactive groups. The behaviour of the resin solutions in a pressure process as well as the penetration parallel and orthogonal to the grain were investigated. Further, resin-uptake, improvement of hardness, and dimension stability, were examined. SEM studies are intended to show penetration pathways and linkage of the resins to the cell wall. Running tests on the investigation of the resistance against basidiomycetes and softrot fungi are not yet completed.
A O Rapp, R-D Peek


In situ testing the influence of melamine resins on the enzymatic activity of basidiomycetes
1999 - IRG/WP 99-30194
Waterbased methanol etherificated melamine formaldehyde resins have the potential to increase the resistance of impregnated wood against wood destroying fungi. The mechanism of the increased wood durability is not clear yet. In the present paper the possible interference of melamine resins with wood degrading enzymes of Coniophora puteana and Trametes versicolor was investigated as a possible contribution to the increased wood durability. An in situ photometric assay was used to measure the enzymatic activity against Walseth cellulose, pine sapwood as well as lignin and xylan preparations.
D Lukowsky, F Büschelberger, O Schmidt


Preservatives stains as exterior wood finishes
1977 - IRG/WP 389
For many years wood preservatives and paints have been used as the only treatment for exposed wood surfaces. Because of the inherent color of the preservatives, such as creosote, the wood surface was stained as well as protected from attack by micro-organisms. Paints protect surfaces from weathering, but recently, with an increased interest in maintaining the more natural appearance of exterior wood surfaces, painting is being replaced by staining. Stains have the advantages, in addition to preserving the natural wood appearance, that they do not peel, blister or crack, can be applied easily and renewed with little difficulty. The cost is less than that of paint, initially and over the life of the building. One of the major attractions for homes is that stains blend in with the environment. If the home owner desires a white exterior or bright colors, paint rather than a preservative stain must be used. Paints are more effective in protecting the wood from damage by sunlight and will avoid discoloration of the exterior surface resulting from the natural extractives present in wood. Special aluminium or stainless steel nails are not needed with paints, but are needed with stains. Preservative stains can be classified in various ways. Wood preservatives, such as creosote and pentachlorophenol, have been used for many years primarily for preventing deterioration caused by fungi, including fungus species which discolor and those that decay the wood. These compounds provided some degree of water repellency, but this was not a major objective in their use. Later, water repellents were added to the preservatives to reduce the rapid uptake of moisture and thus provide some dimensional stability to the product. More recently water solutions of inorganic salts have demonstrated that they provide protection to the wood, add color and are beneficial primary treatments if the wood surface is to be painted. Some of the water soluble formulations may provide some fire retardant properties as well. A common system of classification today includes three general types of natural finishes as follows: 1. water-repellent preservatives; 2. pigmented penetrating stains; 3. inorganic water soluble salts. It is possible to obtain a satisfactory exterior surface if no treatment is applied. Such an approach, however, is satisfactory only where the weather is not favorable for micro-organisms. If the fungi and other micro-organisms are allowed to develop, the coloring will be very nonuniform, the wood surface will deteriorate, and warping and the like will occur to excessive degrees. Thus in most environments one of the above systems must be used.
D W French


Compatibility of deltamethrin with wood adhesives
1993 - IRG/WP 93-30031
This work presents the studies conducted on the compatibility of deltamethrin when mixed with wood adhesive to manufacture plywood in order to protect the wood against wood-borers insects and termites. The following types of adhesive were tested: PVA, Urea-formaldehyde, phenol-formaldehyde and a formulation based on tannin. The experiments were made in the adhesive manufacturers' laboratories, where the conditions to which the adhesives are submitted during the manufacturing process were simulated. To verify the effectiveness of the adhesive mixed with deltamethrin the block tests were exposed to subterranean termites, Coptotermes havilandi. The tests showed that the internal layers of the plywood made with adhesives based on PVA and Urea-formaldehyde were protected for 40 months.
A M F Oliveira


Algal growth resistance of paints for coating of wood; a laboratory study
1997 - IRG/WP 97-10213
Twelve paints were tested for resistance against algae. In addition, one algicidal compound commercially used for remedial treatments of algal growth on paints was tested for its effectiveness for prevention of algal growth. An agar diffusion bioassay was employed in which paint films on filter paper discs were placed on mineral salt medium and sprayed with an algal suspension containing a mixture of one blue-green alga, Oscillatoria tenuis, and two green algae, Ankistrodesmus gracilis and Pleurococcus sp. Most growth was recorded in plates with discs painted with acrylic paints. Two acrylic paints containing a commercial fungicide at normal or double concentration permitted the same amount of growth as the same acrylic paint without fungicide addition. The solvent-borne alkyd paints and the alkyd emulsion paints were more inhibitory against growth of algae. Only some of the acrylic paints permitted any growth of the green alga Ankistrodesmus gracilis. Acrylic paints containing a commercial algicide inhibited the growth of the Pleurococcus sp. and Ankistrodesmus gracilis but permitted some growth of Oscillatoria on the agar medium used.
J Bjurman


Melamine resins as preservatives results of biological testing
1996 - IRG/WP 96-40061
Based on previous work of the authors on resins, the upgrading of wood with a true solution of a methanol etherificated melamine resin in low aqueous concentration was performed. For the relative assessment of the biological resistance against brown and white-rot fungi were used not only untreated controls of pine sapwood (Pinus sylvestris L.), but also heartwood of European larch (Larix decidua Mill.). Even at the lowest applied concentration of 7.5% resin in the treating fluid (about 10% weight gain), the treated wood showed considerably less mass loss than heartwood of European larch. Leaching according to EN 84 resulted in no difference. The above outlined is valid for lab tests according to EN 113. First results of ongoing experiments with samples in soil contact exhibited general problems of testing modified and resin treated wood, using standard methods made for classical wood preservatives.
A O Rapp, R-D Peek


The resistance of wood coated with different water-borne paints against colonisation by decay fungi
1996 - IRG/WP 96-10165
The susceptibility of wood painted with model paints of known composition to decay fungi was tested without previous weathering. Included in the study were five alkyd emulsion paints and five acrylic paints; one linseed oil paint and two solvent-borne alkyd paints. It was found that several components influenced the susceptibility of these paints. The results of the present study indicate that the particle size of latex paints, the pigment volume concentration and the amount and type of surfactant in the water-borne paints are critical for colonisation by decay fungi of painted wood. An anion surfactant was somewhat fungicidal. The results are briefly discussed in relation to major paint components and to available knowledge of the properties of water-borne coatings on wooden substrates. The present study is part of a larger project aiming at improvement of the durability of painted wood.
J Bjurman


Silicon compounds as additives improving alkyd-based wood coatings performance
2010 - IRG/WP 10-40531
The reactivity of cellulose with solvent-born alkyd-based wood coatings supplemented with organosilanes was analyzed. Structural analysis of cellulose subjected to the reaction with organosilanes and following extraction with water was performed using Fourier-transform infrared spectroscopy (FTIR). The analyzed IR spectra comprise bands 1250 cm-1 typical for the SiC group and 800 cm-1 typical for vibrations of SiC and/or SiO groups. The presence of these bands in the spectra proves the occurrence of a reaction between cellulose and organosilanes. Silicon concentration in cellulose was determined by AAS after the reaction with coating system after leaching.
B Mazela, I Ratajczak, K Wichłacz-Szentner, P Hochmańska


Bio-based thermoset resins for bonding and eco-friendly preservation in the wood industry
2013 - IRG/WP 13-40650
Yellow dextrins and tannins were used in wood adhesives formulation to substitute resins based on formaldehyde. Several formulations were carried out in alkaline aqueous media by varying the weight fraction of two compounds from 10% to 30%. The cross-linking was performed using epichlorohydrin as a reticulant agent. Rheological behaviours and initial adhesion of three liquid formulations, before reticulation, were carried out by probe tack test and Rheology to validate its process ability. The cross-linking of epichlorohydrin with yellow dextrins and tannins was highlighted in this study. The cross-linking was analyzed by Fourier transformed infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and by biodegradation of reticulated resins. Mechanical properties of resins were analyzed by shear strength test on plywood. Depending on formulations, results confirmed the high potential of yellow dextrins and tannins reticulated by epichlorhydrin, to glue wood. Moreover, the biodegradation tests of cross-linked samples showed that the network constituted by dextrins and tannins are resistant to fungal attack.
C Motillon, A Allal, A Visse, F Charrier, B Charrier, A Baldé


Decay resistance of beech wood and plywood treated with different type of phenol-formaldehyde (PF) resins
2016 - IRG/WP 16-40717
In this study treatment of beech and poplar wood veneers with (PF) resin industrial scale and screening tests of nine different phenol-formaldehyde (PF) resins were made. Specifically, the effect of different phenol-formaldehyde (PF) resin types on the resistance of beech wood against brown- and white-rot fungi was evaluated. Criteria for selection of optimal (PF) resin were based on minimum WPG requirements to achieve equal durability class (1st durability class according to the EN 350 standard) against fungi. Therefore European beech (Fagus sylvatica) wood blocks (15x20x50 mm³) were vacuum impregnated to various weight percent gains (WPGs) with water-soluble PF resins. Different WPG levels were achieved by using aqueous resin solutions at concentrations of 9, 18 and 27 wt %. Treated wood blocks were exposed to brown-rot fungi (Gloeophyllum trabeum (G.t); Coniophora puteana (C.p)) and white-rot fungi (Trametes versicolor (T.v); Pleurotus ostreatus (P.o)) for 16 weeks. A WPG of approximately 8–14% was necessary for beech wood blocks for a treated with the resin C, D, I and E, but approximately 16% and 27% was necessary when using other resins as B, F, G, H, respectively. Irrespective from resin the required WPG for decay resistance against brown rot fungi was approximately 50-60% lower compared to decay resistance against white rot. No effect of resin on the resistance against (G.t) decay of wood blocks was observed, resulting in resin loadings of 7–8%, whereas the required WPG for (C.p) decay suppression slightly increased from 8 up to 11%, respectively. The results suggest that the magnitude of white fungal deterioration of treated wood is strongly affected by the resin used for treatment. Resin loadings from 7% to 17% against (T.v) and from 12% to 27% against (P.o) were required. This broad range in WPG may be due to varied fungal aggressiveness, filling of the cell wall micropores (bulking) and the stiffness (pliability) of the cell wall matrix. From aforementioned, two resins D and E were selected for treatment of beech and poplar veneers on industrial scale and resistance of treated plywood against white rot fungus (T.v) was evaluated according EN 12038 standard.
V Biziks, S Bicke, H Militz


Improvement of wood properties by impregnation with liquefied spruce bark based resins
2016 - IRG/WP 16-40761
In this paper, biobased phenolic thermosetting resins are designed to be used as wood stabilization treatment. The originality of the study stands in substituting part of phenol by spruce (picea abies) bark: this is achieved by a liquefaction process in phenol in the presence of sulfuric acid as catalyst. Next, thermosetting resins are synthetized from liquefied bark by condensation on formaldehyde and further used for impregnation in beech blocks and curing. Two kinds of spruce barks -unmodified and pretreated ones- are used as starting material and characterized. Concerning pretreatment, a hydrolysis has been applied to spruce bark in order to enhance phenolic part. Two liquefaction processes are compared: the first one a simple heating under reflux in presence of phenol. A second one consists in heating at 200°C in closed reactor in phenol/ethanol/water solvent (20/50/30). For the different systems attempted, liquefaction yields are determined and analyzed regarding FT-IR analysis. 91% yield was obtained for liquefied spruce bark under reflux, but the highest bark to solvent ratio (50%) was obtained for process lead in closed reactor. Reactivity of liquefied bark resins is found to be better than control phenolic-formaldehyde resin. Impregnations in beech (Fagus sylvatica) wood blocks are performed using different dried matter content (10%, 20% and 30%). After curing, weight percent gain (WPG), leaching rate, anti-swelling efficiency (ASE) and resistance to decay of different systems are compared. It is shown that liquefied bark based resins confers to wood significant dimensional stabilization and resistance to decay against brown rot and white rot fungi. Concerning the impact of the different processes attempted such as hydrolysis pretreatment or liquefaction at 200°C in closed reactor, final properties of treated wood are decreased compared to liquefied bark resins.
X Duret, E Fredon, E Masson, P Gérardin


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