Your search resulted in 64 documents. Displaying 25 entries per page.
Pretreatments of wood surfaces for improving weatherability of clear finishing
2001 - IRG/WP 01-40196
The clear film durability of wood is generally very short because of photo degradation of wood surfaces caused by UV through to the film. Pre-treatment of wood surfaces for protecting against photodegradation is very important for clear finishing system. In this study, some pre-treatments, ie; polyethylene glycol (PEG) and UVA grafting (2-hydroxy-4(2,3-epoxypropoxy) benzophenone (HEPBP)), were applied to wood surfaces and evaluated the clear finishing durability at outdoors. PEG treatment showed good clear film durability at mild climatic places, however, less durable results were observed at warm and high humid or heavy snow area in Japan. UVA grafting to wood surfaces greatly improved clear film durability as well as chromium trioxide treatment. Mixtures of UVA, HALS and anti mould chemicals system showed to prevent for growing mould on wood surfaces finished with clear or light color exterior stain system.
M Kiguchi, Y Karaoke, P D Evans, Y Kadegaru, Y Imamura
JWPA method for testing effectiveness of surface coatings with preservatives against decay fungi
1981 - IRG/WP 2164
In 1979 JWPA established a new method for testing effectiveness of surface coatings in accordance with practical use of preservative-treated lumber. Comparing the new testing method with JIS A 9302, a few new trials - size of wood specimen, weathering procedure, and decay-test procedure - are incorporated.
Blue stain in service on wood surface coatings. Part 3: The nutritional capability of Aureobasidium pullulans compared to other fungi commonly isolated from wood surface coatings
1993 - IRG/WP 93-10035
The nutritional capability of Aureobasidium pullulans was previously examined, using agar plate tests, with regard to nutrient sources that are potentially available in fresh and weathered wood (Sharpe and Dickinson, 1992). This study compared these findings with the nutritional capability of four other fungi (Alternaria sp., Cladosporium cladosporoides, Stemphylium sp. and Trichoderma sp.) commonly isolated from wood surfaee coatings. The liquid culture techniques were used to assess the relative abilities of the fungi to utilise a range of simple sugars, wood sugar alcohols, hemicelluloses, cellulose and lignin degradation compounds. The observations were used to explain why Aureobasidium pullulans is able to occupy so successfully, often in monoculture, the wood-paint interface niche.
P R Sharpe, D J Dickinson
Leaching of the new boron based biocide from coated wood
2001 - IRG/WP 01-30267
We investigated leachability of the new boron based biocide - a complex of an amine and boric acid - from vacuum impregnated spruce wood samples. It was determined by the standard ENV 1250-2 procedure that the new biocide is susceptible to leaching so from the water borne as well as from the ethanol borne boron containing preservative treated wood. Leaching may be retarded by application of surface coatings. The ability of a surface finish to prevent leaching is correlated to its water vapour permeability.
M Petric, M Pavlic, F Cadez
Blue stain in service on wood surface coatings. Part 2: The ability of Aureobasidium pullulans to penetrate wood surface coatings
1992 - IRG/WP 92-1557
The ability of Aureobasidium pullulans to penetrate seven different wood surface coatings was examined. Eight isolates of Aureobasidium pullulans were used. Following penetration, light microscopy was used to examine the effect of the fungus upon the coating, and growth at the wood-film interface. The fungus showed different growth capabilities with different types of surface coatings. Some isolates were able to penetrate alkyd based coatings, but were unable to grow in the film. In contrast, after penetration through latex based coatings several isolates were able to produce growth in the films themselves.
P R Sharpe, D J Dickinson
Reliability-based service life prediction methodology for assessment of water protection efficiency for coatings on wood
2003 - IRG/WP 03-20268
Assessment of water protection efficiency according to EN 927-5 has been shown to give significant differences in water absorption values for different types of coatings on wood. It is shown that the combination of EN 927-5 and an artificial weathering procedure gives more information regarding expected durability and long-term performance than a single measurement of water absorption on fresh, unweathered wood. A combination of water absorption measurement and artificial weathering could become a useful tool in product development as well as in benchmarking. Together with statistical tools, such as reliability-based service life prediction methodologies for prediction of the service life of coating systems a reduction in testing time may be achieved. The predicted service life can then be the input to integrated life cycle assessment of products for wood protection.
A collaborative test to determine the efficacy of polyurethane coatings on wood samples exposed in the marine environment
1984 - IRG/WP 4113
Aims are: a) to determine the effectiveness of elastomeric polyurethane as a protective coating against marine wood boring animals in a range of tropical and tempreate sites; b) to compare the adhesion of polyurthane coatings on different wood species exposed in seawater; c) to record the severity of attack in failed samples and to identify the causal marine organisms.
R A Eaton
Surface coatings for impregnated wood
1992 - IRG/WP 92-3684
The use of proper surface coatings enhances the aesthetic and protective properties of impregnated wood. Good results with especially water-borne coatings have been obtained for class-A impregnated L-joints and claddings in field tests started in 1982.
Evaluation of the leach resistance and preservative efficacy of novel biocides as surface treatments applied by brush to spruce (Picea abies)
1998 - IRG/WP 98-30170
The comparative leach resistance and preservative efficacy of a number of alternative organic preservatives (available from Zeneca Specialties) and selected commercially available biocides as surface coatings to wood in Hazard Class 3 have been assessed. Two concentrations of test preservatives were applied by brush to Spruce (Picea abies), including formulation and untreated controls. A leaching program was carried out involving the immersion of the treated blocks in water for a scheduled period of time. Blocks were then subjected to biological tests to determine preservative efficacy using the basidiomycetes Coniophora puteana and Gloeophyllum trabeum in a modified EN 113 system; sapstain and mould tests were separately undertaken according to a modified EN 152 test using mixtures of Aureobasidium pullulans and Sclerophoma pithyophila, and Trichoderma harzianum and Trichoderma saturnisporium. Of the four alternative actives tested, one Zeneca development product based on Hexaconazole compared very favourably against the selected commercial biocides tested. An aqueous system based on a Zeneca penetrating aqueous polymer coupled with the Zeneca development active demonstrated favourable performance in relation to an existing solvent based product.
I M Tierney, A Bruce, D C R Sinclair, T Yeates
A collaborative test to determine the efficacy of poyurethane coatings on wood samples exposed in the marine environment. 1st Interim Report
1988 - IRG/WP 4145
Wood samples coated with elastomeric polyurethane (ca. 50 mils thick) were exposed for up to 2 years in 12 tropical and temperate marine test sites with known teredinid, pholad and/or crustacean infestations. All uncoated control samples were destroyed or partially destroyed. Polyurethane-coated samples were not attacked, the surfaces of the coating were sound and the polyurethane adhered well to the wood samples.
R A Eaton
The efficacy of polyurethane coatings on wood samples exposed in the marine environment. Final Report -10 Year Assessment
1996 - IRG/WP 96-10170
The results of an IRG collaborative marine trial to investigate the long-term permanence and efficacy of polyurethane coatings against marine borers are reported. PU-coated wood samples were exposed at a range of sites from tropical to cold temperate locations. The marine borer species present at the sites included teredinids, pholads, limnoriids and sphaeromatids so that each site offered its own peculiar degree of hazard. At most sites the integrity of the PU-coating was sound and wood samples were undamaged by marine borers after periods of exposure extending up to ca. 10 years. Where damage to the wood was recorded, mechanical abrasion of the coating had exposed the wood to attack by teredinids and pholads at one site and at a second site, sphaeromatids had perforated the coating. The significance of the results is discussed in terms of the protection afforded to submerged maritime timber structures coated with elastomeric polyurethane.
R A Eaton
Influence of a dipping preservative treatment on the performance of wood finished with waterborne coatings
1998 - IRG/WP 98-40121
Within a larger European research project on the performance of joinery finished with waterborne coatings, the influence of a water based dipping preservative treatment was studied in several ways. Six different waterborne coatings were tested with and without a preservative underneath the coating. The performance was tested on pine sapwood and spruce panels in a 2-year outdoor weathering trial on two different sites in Europe. The panels were evaluated visually with respect to cracking, flaking, surface mould growth and development of blue stain underneath the coating. In several cases the preservative treatment improved the performance of the coating, not only with respect to biological deterioration but also for cracking and flaking of the paint. A limited number of coatings were also tested on L-joints according to the EN-330 and of national dutch design. The EN-330 L-joints appeared to be a more challenging substrate compared to the national type, which had a glued connection between tenon and mortise. The influence of the preservative on the moisture content of the wood was evaluated by monthly weighing of the samples exposed outdoors and by laboratory measurements of the coating permeability. At least in laboratory trials the dipping treatment caused a slight reduction of the water permeability. This is most likely the result of the polymeric binder material present in the preservative. The presence of polymeric material underneath the coating was also confirmed in a microscopic evaluation of the distribution of the dipping preservative. The preservative was not equally distributed in the wood, but showed a clear preference for the ray-tissue.
M De Meijer, J Creemers, W Cobben, P Ahola
Observations on the uptake and penetration of various liquids in clear heartwood and sapwood of Pinus radiata D.Don
1983 - IRG/WP 3224
Volumetric uptake of water (aqueous copper-chrome-arsenic (CCA)) or methanol, applied by bulk hydrostatic pressure to air dried clear heartwood specimens of Pinus radiata D. Don, far exceeds that of a wide variety of polar and non-polar solvents. In air dried sapwood, the volumetric uptake of CCA tends to be less than that achieved for most solvents including methanol. No comprehensive explanation of the penetration mechanism in these two substrates can yet be offered. High temperature drying effects a significant increase of volumetric uptake of all liquids by heartwood, but not by sapwood, possibly because air dried material is nearly saturated after pressure treatment.
J E Barnacle
Blue stain resistance of exterior wood coatings as a function of their typology
1998 - IRG/WP 98-20145
Paints and wood stains were evaluated on their blue stain resistance using both EN 152 method and the reverse method. The typology of these exterior coatings was varied including standard and high solid solvent-borne coatings as well as different types of waterborne coatings. For the water-borne acrylic, alkyd based and hybrid coatings both applied as opaque primer paints and as decorative wood stains a range of synthetic resins were used. Though some components like dryers or bactericides are present in a number of formulations examined, a clear tendency of dependence of blue stain resistance on the typology of the coating seems obvious when evaluating blue stain development in an early stage. Longer exposures to test fungi fade away the effect of resin and indicate the role of a chemical protection of the coating.
J Van Acker, M Stevens, C Brauwers, V Rijckaert, E Mol
Evaluation of some polyurethanes as protective marine coatings for wood
1985 - IRG/WP 4115
Several polyurethane formulations were evaluated in the marine environment as possible replacements for Irish felt used on U.S. Navy minesweepers as a marine borer barrier between the main wooden hull and an outer, wooden sheathing which covers it. Pine panels coated with the candidate materials were tightly juxtaposed with untreated pine baitwood to simulate the hull/sheathing configuration, the baitwood serving as a substrate in which settling borer larve could metamorphose. Primarily, the purpose was to see if adult borers could perforate the coatings at the coating/wood interface and enter the wood beneath, however the ability of these coatings to survive in sea water for an extended time was also noted. Panels were exposed from 48 to 89 months in Panamanian waters. Teredinids were able to perforate four of the coatings from the baitwood; pholads were able to perforate all of the coatings with ease and were the major cause of coating damage at the coating/baitwood interface. None of the coating surfaces exposed directly to the sea water were damaged by teredinids or pholads, however the coatings on some of the panels were eventually reduced to tatters with large sections of the original specimen missing. This was a result of borer infestation of the underlying wood via prior pholad-induced holes which were uncovered when the panel faces were reversed in the panel/baitwood configuration during the exposure.
J D Bultman, J E Pinto
A collaborative test to determine the efficacy of polyurethane coatings on wood samples in the marine environment. 2nd Interim Report
1990 - IRG/WP 4161
The results of a collaborative international test to evaluate the performance of elastomeric polyurethane coatings of wooden test samples exposed in seawater at 13 sites around the world are reported. The samples have been exposed at sites with known infestations by molluscan and/or crustacean wood borers. Performance data for up to 4 years exposure at some sites is presented providing information on the soundness and adherence of the coatings to wood and the degree of surface fouling. To date, all samples coated with polyurethane remain unattacked by marine borers.
R A Eaton
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
Blue stain in service on wood surface coatings. Part 1: The nutritional requirements of Aureobasidium pullulans
1992 - IRG/WP 92-1556
The nutritional requirements of Aureobasidium pullulans was examined with regard to nutrient sources that are potentially available in fresh and weathered wood. The study was designed to determine how far wood cell wall components need to be broken down during weathering before they provide a useful nutrient source for Aureobasidium pullulans. Various carbon sources were tested, with eight different isolates of Aureobasidium pullulans. It was found that the organism could utilise the simple sugars well, but not the oligosaccharides. The organism was also able to utilise well several lignin precursor compounds.
P R Sharpe, D J Dickinson
A collaborative test to determine the efficacy of polyurethane coatings on wood samples in the marine environment. 3rd Interim Report
1993 - IRG/WP 93-10046
The results of al long-term marine trial to assess the protective effect of polyurethane coatings on wood samples exposed at different sites around the world are reported. The condition of samples exposed in the sea for up to 88 months was generally sound, although instances of marine borer infestation were reported at two sites. At one site, mechanical damage of a non-biological nature is believed to have breached the polyurethane coating resulting in attack of the underlying wood by teredinids and pholads. At a second site, infestation by sphaeromatids had perforated the coating after 4 years exposure.
R A Eaton
Minimisation of the Environmental Impacts of Coatings on Exterior Wood by Optimisation of their Life Spans
2003 - IRG/WP 03-50197
The study has shown that the environmental impacts from coatings on exterior wood are dependent criteria on their life spans. A minimisation of the environmental impacts can be performed with the help of the integrated design model, which is tested in this study. The optimal life spans, found as reference service lives from the exposure tests, statistical evaluation and the assessment of experts were used for forecasting in Life Cycle Assessment of the coatings on exterior wood. The integrated life cycle design, performed in this study, showed that the water-borne acrylic coating and the water-borne acrylic stain are the best choice as regards the integrated assessment of the environmental impacts and service lives of the coatings. The discussed coating systems are a solvent-borne alkyd coating, a water-borne acrylic coating, a water-borne acrylic stain, a solvent-borne alkyd stain and an alkyd oil.
Enhancing the Performance of Transparent Coatings by UV Protective Pre-treatments
2006 - IRG/WP 06-30399
Most industry observers anticipate a change from copper-based preservatives to metal-free combinations of organics for residential treated wood products in North America within the next one to five years. While the chromium copper provide considerable protection against UV, metal-free formulations will need UV protection in the form of additives or coatings. While transparent coatings can be made reasonably resistant to UV, by necessity clear coatings are transparent to visible light. Visible light can also cause damage over the long term thus the underlying wood needs additional protection. Four novel UV protection systems were tested as pre-treatments on uncoated wood and under three coatings, a water-based film forming coating, a water-based acrylic varnish and a solvent based water repellent. Samples were exposed to natural weathering facing South at 45o at a test site in Saucier, Mississippi, in collaboration with the USDA Forest Products Laboratory. The test material was inspected every six months for discolouration, mold and stain, coating water repellency, flaking, erosion and cracking and substrate condition. After 24 months exposure, coatings over the combination of UV absorber and lignin stabilizer identified by Stephen Ayer and that recommended by Ciba and were both performing substantially better than controls with no pre-treatment. Projection of fitted curves beyond the data appears to indicate that pre-treatment may double the life expectancy of the coating. There was no consistent effect of the synergists on either combination at this time.
P I Morris, S McFarling
Photo-degradation of modified and non-modified wood, coated with water borne acrylic coatings during artificial light exposure
2007 - IRG/WP 07-30416
A series of experiments were carried out to investigate photo-degradation of thermally modified (at 210oC and – 0.9 bars for two hours) and non-modified spruce wood (Picea abies L (Karst)), coated with transparent and semitransparent (with 3% pigment content) acrylic coatings during artificial UV light irradiation for 200 hours. Photo-degradation was evaluated in terms of colour changes throughout the irradiation period at an interval of 50 hours, along with IR and EPR spectroscopic study. One set of modified and non-modified woods was painted with coatings, while the other set was covered with free films made of coatings, just to simulate coated wood. The average thickness of paint-coats and dried free films at 25oC and 50% RH was 144.8?m and 143.4?m for transparent and semitransparent coating, respectively. The colour changes for both modified and non-modified wood samples without paint-coat and free film cover were comparable to that of wood samples with paint-coat and free film cover for transparent coat type, which indicated its ineffectiveness to prevent photo-degradation of wood underneath. However, the colour changes for both modified and non-modified wood samples with paint-coat and free film cover were much more lower than that of samples without paint-coat and free film cover for semitransparent coat type, which might be due to hindrance of transmission of light energy through pigment to reach the underlying wood surface. On the other hand, whole substrate-coating systems showed better photo-stability, when thermally modified wood was used as substrate. It might be due to increase in lignin stability by condensation during thermal modification process of wood substrate. However, the colour changes of coat-painted and free-film covered samples for both modified and non modified woods might be due to due colour changes of wood specimen underneath, because free films of both the coat types showed negligible colour change during UV irradiation.
M Deka, M Tomažic, M Petric
Micro- and hydro-sandblasting for wood and wood coatings
2007 - IRG/WP 07-40380
Exterior wood coatings are getting increasingly durable and often more film forming. As a result they become difficult to renovate. Conventional renovation techniques (chemical or thermal stripping, sanding) are demanding techniques which take a long time to implement. Therefore renovation techniques are requested which are easier to use and which ensure that the wood surface is suitable for a re-coating. Abrasive sandblasting is commonly used to restore buildings. However traditional sandblasting is too aggressive for wood especially because of the pressure generally used in such a process. There are two renovation techniques which are of interest: hydro-sandblasting and micro-sandblasting, these are both renovation techniques used in other industrial sectors and operating at lower pressures. In the first method a mixture of water, abrasive particles and air are propelled towards the surface. The second one is similar, but operates without the addition of water. This paper presents different investigations carried out with these two surface cleaning techniques on wood and wood coatings. The influence of the abrasive media was studied and showed that plastic or vegetable media were not effective whereas crushed glass grit gave good results. The investigations have shown that these methods both are very efficient to remove old coating material from wood. When aged uncoated wood samples are considered, the techniques allow the samples to get back free of greying. Three coating systems have been used to study the re-paintability of blast cleaned wood. Natural and artificial weathering results highlight the importance to use coatings systems with a high solids content when sandblasted wood has to be re-painted in order to cover any surface irregularities created by the sandblasting process. Scanning Electron Microscopy has revealed that sandblasting particularly affects the structure of the earlywood and leads to cells compression. The abrasive techniques leave a topography reflecting the variations in wood hardness. With Electron Diffraction X-ray analysis some glass particles have been detected in the wood structure. Comparing their initial sizes with those measured inside the wood shows that the impact with wood during the cleaning break the abrasive particles. Their presence in the wood structure do not seem to affect the performance of the stain used for renovation.
L Podgorski, V Georges, P Svane
Formulating aesthetic coatings to prevent carpenter bee infestation
2007 - IRG/WP 07-30438
Our study shows that carpenter bees are getting more and more aggressive in attacking construction wood in the USA and southern parts of Canada, causing more-than-cosmetic damages. We have responded to a number of customers’ requests to identify and eradicate the culprits but the new generations of the bees would attack the same structures again. Therefore, Sansin invested into a project to formulate a decorative coating with a preventive action against carpenter bee infestations. Preliminary tests and results are reported in this paper.
Distribution and availability of preservative components in ACQ treated wood - effects of coatings and weathering
2010 - IRG/WP 10-30537
Copper and quaternary ammonium compound (quat) distributions across lumber (gradients) and availability, as measured by amount removed by intensive leaching of wood flour, were measured in ACQ treated southern pine lumber. Samples were evaluated just after treatment and stabilization, or after 3 years of laboratory storage, or after 3 years of natural weathering exposure. The objective was to investigate how the distributions of copper, quat and monoethanolamine (MEA) changed under different exposure conditions to try to explain the long terms effects of semi-transparent wood coatings to reduce leaching, even after partial failure of the coatings. In unweathered lumber, there was a slight copper gradient from the surface to the interior of the lumber and a steeper quat gradient. Analysis of specimens after 3 years of weathering exposure confirmed the effectiveness of the coatings to reduce copper and quat leaching and showed that quat leaching from uncoated samples was substantial. There was little effect of aging indoors on availability of ACQ components. However, the availability of copper was significantly reduced after 3 years of natural exposure, even after accounting for the copper that leached during weathering. It was observed that the MEA availability was greatly reduced, presumably by preferential leaching compared to copper and quat during weathering. This appears to have reduced the amount of soluble/available copper resulting in lower long term copper leaching, especially in coated samples that were protected from high copper losses by the effect of the coating. The reduced quat leaching from coated samples is attributed to the long term effectiveness of the coatings in the earlywood portions of the samples.
T Ung, M Nejad, P Cooper