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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

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

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

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

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

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

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

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

Effect of pretreatment of wood surfaces with a copper monoethanolamine solution on the natural weathering performance of semitransparent stains
2019 - IRG/WP 19-40881
Semitransparent stains for wood products are favored for outdoor applications in Japan because these finishes do not hide the wood grain. However, the photoprotective effects of wood surfaces are low, therefor there is a need to improve the weathering performance. We examined the natural weathering performance of semitransparent stains on wood pretreated with a copper monoethanolamine solution (CuA) to improve its photostability. Untreated and pretreated with CuA Japanese larch (Larix kaempferi), Todo fir (Abies sachalinensis), and Japanese cedar (Cryptomeria japonica) wood panels were finished with semitransparent stains containing a different type of resins and colours and exposed outdoors in Hokkaido, Japan for 24 months. Results from the visual assessment and statistical analysis using the Kaplan-Meier estimates of survival analysis showed that the formation of cracks predominantly observed and the stains performed better on pretreated than untreated panels. We conclude that the natural weathering performance of semitransparent stains can be enhanced by using CuA pretreatment. However, further studies would be needed to clarify the reason why the effectiveness of CuA pretreatment differ from resin type and/or wood species.
S Isaji, H Shibui, Y Hirabayashi

Optimized composition of alkyd emulsion with nanoparticles of iron oxide for enhancing protection of thermally modified wood
2022 - IRG/WP 22-40940
Thermal treatment is acknowledged as an environmentally friendly method to improve durability of wood and some of its properties, such as biological resistance, dimensional stability, reduced hygroscopy. Despite these improvements, when used outdoors, also thermally treated wood is subjected to the action of environmental factors, like solar radiation, moisture, precipitations, temperature, etc., giving place to a series of chemical and structural transformations, defined as “weathering”, which negatively affect its service life. In this research an alkyd emulsion containing red transparent iron oxide pigments was obtained, whose composition is optimized to protect the decorative properties of thermally treated wood during outdoor exposure. In particular, attention was dedicated to the selection of surfactants for the emulsification of resins and to the investigation of oxidative properties of alternative metal primary driers, which could replace the cobalt. Initially the surface wetting properties of thermally treated wood were investigated and considered for the optimization of the alkyd emulsion formulation. The determination of the surface energy of wood, by means of contact angle, before and after thermal treatment shows that the polar component of the surface energy decreases with increasing temperature of thermal treatment. This explains the more hydrophobic character of thermally treated wood, which must be considered for the formulation of suitable paints and the selection of appropriate additives. In the second part of the research, artificial weathering test was carried out to determine the suitable concentration of red transparent iron oxide pigments, which can give better protection against photodegradation and minimize the color changes of wood surface. The obtained results show that a concentration of 8 % for red transparent iron oxide pigments in alkyd emulsion is necessary to ensure protection of the thermally treated wood surface. Another important conclusion from the obtained results is that the replacement of organic solvent with water is possible and paint with comparable or even better efficiency can be obtained.
E Sansonetti, D Cīrule, I Andersone, B Andersons, E Kuka