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Flame treatment is an ancient technique for surface protection of wood. Further processing of charred wood elements depends on aesthetic and protective requirements. This study presents some general properties and weathering behaviour of the Norway spruce (Picea abies (L.) Karst.) and the European larch (Larix decidua Mill.), protected by variations of sanding, charring, charring + brushing, and coating treatments. Charring and charring + brushing reduced the original mass of the samples by up to 8% and notably changed their colour (ΔE* ≤ 75). A study of chemical properties showed that charring dehydrated the wood and degraded lignin and hemicelluloses. The surface roughness of the wood after charring and charring + brushing increased by as much as 560%, while coating with waterborne acrylic high build stain had no effect on the roughness of these surfaces. The type of surface treatment of the wood did not affect the uptake of the coating in the wood samples, but the uncoated and coated spruce wood absorbed more water than larch wood. Higher water absorption was observed in the samples treated by charring, and it decreased when the char layer was removed by brushing. The film of a waterborne high build stain reduced water uptake only for surfaces treated by sanding and charring + brushing. Larch wood exhibited higher surface hardness (EHz ≤ 1.70 MPa) than spruce wood (EHz ≤ 0.89 MPa), with the brittle char layer reducing the determined hardness of the tested surfaces. During two years of natural weathering, the char layer was removed from the wood surface, even if the samples were additionally coated. The greatest colour changes during weathering were observed on samples treated by sanding (ΔE* ≤ 60) and sanding + coating (ΔE* ≤ 33), followed by samples treated with charring + brushing (ΔE* ≤ 10) and samples treated with charring (ΔE* ≤ 9). In summary, treating wood by charring in combination with brushing was the best wood protection technique.

Po premazovanju lesa in izpostavitvi zunanjim klimatskim pogojem in/ali višjim temperaturam lahko na mestih, kjer so prisotne grče, pride do obarvanja utrjenega filma, ki ga povzročajo hidrofilni in lipofilni ekstraktivi. Zaradi tega je odpornost premaznega sistema proti obarvanju zaradi grč v lesu zelo pomembna. V naši raziskavi smo preizkusili nekaj osnovnih tipov belo pigmentiranih sistemov. Pri tem smo metodo SIST EN 927-7:2020 ustrezno prilagodili našim zmogljivostim, jo optimizirali in kritično presodili, ali so kje možne izboljšave standardizirane metode. Rezultati naše raziskave so pokazali, da je odpornost premaznih sistemov proti obarvanju zaradi grč v lesu povezana z vrsto topila v premazih, s prekrivnostjo sistema in njegovo slojnostjo oz. debelino suhega filma. Premazi na osnovi organskih topil so se izkazali za boljše, prav tako tisti, ki so vsebovali več pigmentov, in tisti z večjo debelino suhega filma. Prav tako smo dokazali, da lahko z vrednotenjem barvnih razlik na mestih z grčami in brez njih že pred izpostavitvijo in upoštevanjem te izhodiščne barvne razlike pri vrednotenju razlik po izpostavitvi premazne sisteme veliko bolj objektivno razvrstimo po njihovi učinkovitosti proti obarvanju zaradi grč v lesu. Na podlagi te ugotovitve menimo, da je standardizirano metodo potrebno ustrezno korigirati.

A non-thermal plasma treatment generated in air at atmospheric pressure was used for surface modification of medium density fiberboard (MDF) substrate. Untreated and plasma-treated substrates were coated with a waterborne acrylic coating and exposed to accelerated artificial weathering (AAW) in interior mode. Plasma treatment increased the surface free energy of MDF by about 50%, which positively influenced on the wettability of the MDF with the coating. Weathering of the coated MDF caused a decrease in surface gloss and color changes, which were less pronounced for plasma-treated samples. Attenuated total reflection Fourier transform infrared spectra and microscopic analysis revealed degradation of the acrylic resin on the coated MDF due to light irradiation during weathering. After 250 h of weathering, the surface roughness of the coated MDF increased by about 3 μm. The coated MDF surfaces started to lose their hydrophobic character after 50 h of weathering. Finally, the determination of mechanical properties showed that coated MDF became more resistant to scratching during AAW, while the adhesion of the coating film to the MDF substrate was not affected in a significant trend with time of AAW. In both cases, no influence of plasma treatment was detected.

The aim of the study was to produce different types of coatings based on natural dyes obtained from invasive alien plant species and residues after paper production. As a source of dye we used extracts of Rhus typhina, Japanese knotweed, Himalayan balsam and Canadian and giant goldenrod. The substrates for the application of the coating were the wood of the tree of heaven and the wood of the horse chestnut. The coatings were observed visually, and the hydrophobicity of the coated surfaces was determined by measuring the contact angles of water droplets. In addition to the transparent and brown coloured coatings, we also achieved intense red, yellow, green, and brown and purple colourings. With a combination of different components, the hydrophobic properties of the coated surfaces varied. By combining an extract of giant goldenrod flowers and 3-(triethoxysilyl)propyl isocyanate, we succeeded in producing a coating with pronounced hydrophobicity. A process for the production of coloured and transparent hydrophobic coatings was developed in this research. Through the presence of various silane-containing molecules and the application of the coating to wooden surfaces, we changed their appearance and improved their hydrophobicity.

Cilj raziskave je bil pripraviti različne tipe premazov na osnovi naravnih barvil, pridobljenih iz invazivnih tujerodnih rastlin ter iz ostankov proizvodnje papirja. Kot vir barvil smo uporabili ekstrakte iz octovca, japonskega dresnika, žlezave nedotike ter kanadske in orjaške zlate rozge. Podlaga za premaze sta bila les velikega pajesena in les navadnega divjega kostanja. Premaze smo opazovali vizualno, hidrofobnost premazanih površin pa ugotavljali z metodo merjenja stičnih kotov kapljic vode. Poleg prozornih in rjavo obarvanih premazov smo dosegli tudi intenzivna obarvanja, od rdeče, rumene, zelene, rjave do vijolične barve. S kombinacijo različnih komponent so se spreminjale hidrofobne lastnosti premazanih površin. Uspelo nam je pridobiti premaz z izrazito hidrofobnostjo, in sicer iz kombinacije ekstrakta iz cvetov orjaške zlate rozge in 3-(trietoksisilil)propil izocianata. V okviru raziskave je bil razvit postopek za pripravo barvnih ter transparentnih hidrofobnih premazov. S prisotnimi različnimi silanskimi molekulami in z aplikacijo premazov na površine lesov smo tako spremenili njihov izgled in izboljšali njihovo hidrofobnost.

The paper presents the use of low-temperature plasma, generated in the air at atmospheric pressure, for treatment of wood surfaces to improve their wettability. For this purpose, a dielectric barrier discharge plasma device with a floating electrode configuration was used. The density and homogeneity of the plasma discharge, formed between the isolated high voltage electrodes and the surface of the spruce (Picea abies(L.) Karst.) and beech (Fagus sylvaticaL.) wood, was shown to be highly dependent on the size of the gap between the electrode and wood. Topography measurements using a confocal laser microscope showed that exposure of wood to plasma causes changes on its surface at the sub-microscopic level. Measurements of the contact angles of water droplets and water-based coating showed the improved susceptibility to wetting of treated surfaces. Differences in surface wettability were also detected depending on the selected machining parameters: type of wood, workpiece feed speed, the distance between the electrodes, the distance between the electrodes and workpiece, and workpiece thickness.

Staining of wood with various substances and processes is an important part of surface finishing of wood. Colour differences as a result of staining and of exposure of coloured wood during its utilisation are usually evaluated by instrumental measurements. However, the measurement results can show something else compared to what our naked eye can see. Due to inhomogeneity of wood, this discrepancy can be even greater in the case of finished surfaces. The aim of our research was to evaluate distinctions between visual perception and numerically determined colour differences on differently finished wooden surfaces, to get information at which starting point the colour difference becomes visible, and to establish whether it is related to the nature of the surface. We established that the visual assessment is influenced by many factors and that there is a correlation between visual and instrumental assessments. The colour difference ΔE* of 0.5 should be considered as a value when it starts to become visible, and at the value of 2.0, observers already considered the colour difference as a different colour. It was stated that we have some tolerance in perceiving the colour change. This tolerance is more expressed in the case of transparent coating systems.

The purpose of this study was to comparatively investigate the behavior of silicate and sol-silicate coatings non-modified or modified with an organosilane on wood and on wood pre-coated with silica-mineralized primers. Adhesion strength, morphology, and water permeability and related damages were studied to evaluate the possibility of utilizing such inorganic-based coating systems for durable protection of wood without or with relatively cheap and water-borne primers. Potassium silicate and potassium methylsiliconate aqueous solutions and a colloidal silica were used for the preparation of the coatings. The white coating paints were brushed on beech wood substrates at a rate of 220 g·m−2. The coatings exhibited good coverage ability. The pull-off adhesion strength values appeared to be related to pH following a polynomial law. The adhesion strength for the silicate coatings were adequate (above 3 MPa and up to 5 MPa) for wood, whereas the values for the sol-silicates were too low for practical applications. The adhesion values were in general higher for the samples cured in a climate room (23 ± 3 °C and 75 ± 2% relative humidity) than the samples cured in the ambient atmosphere of the laboratory (23 ± 3 °C and 25 ± 5% relative humidity). The presence of microdefects (cracks, holes) was revealed in the coating layers by optical and scanning electron microscopy. The surface roughness parameters assessed by confocal scanning laser microscopy were dependent on the magnification applied for their measurement. The arithmetic average roughness Sa was between 5 µm and 10 µm at magnification 5× and between 2.5 μm and 10 µm at magnification 20×. The maximum peak-to-valley height Sz confirmed the presence of open pores emerging through the coatings. The open pores constitute free pathways for water ingress through the coatings, and could explain the high water absorption of the coatings including the methysiliconate-containing silicate coating and despite the relatively high water contact angle and low wettability exhibited by this sample. The post-application of a hydrophobizing solution containing hexadecyltrimethoxysilane and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride considerably reduced the water permeability, while application of nanosilica-containing organic primers increased the adhesion for the coatings. Silicate coatings with adhesion great enough and resistance against water damages can be generated on wood even without a primer using low silica-to-alkali ratio binders and an organosilane additive. The sol-silicate coatings appear to be applicable only with a primer. The improvement of the paint formulations to control the formation of microcracks and open pores could be useful to reduce the liquid water permeability and increase durability. Otherwise, the application of a hydrophobizing treatment can be used for this purpose.

The aim of the study was to prepare a bionanocomposite based on polylactic acid (PLA) with the addition of nanofibrillated cellulose (NFC) as a reinforcement component. For the production of the composite we used unmodified and acetylated NFC (A_NFC). Freeze-dried NFC was acetylated in a heterogeneous system with acetic anhydride in di- methylformamide (DMF) in the presence of pyridine as a catalyst. The success of the acetylation was determined by FT-IR spectroscopy. PLA films were prepared with the addition of 2.5 %, 5 % and 10 % of unmodified and acetylated NFC. The focus of this research was the impact of the NFC additive on the transparency and on the resistance of the biona- nocomposite to scratching. The transparency of the bionanocomposite film was measured using UV-Vis spectrophoto- metry, and the resistance of the films to scratching was evaluated with a scratch test. The optimal amount of NFC and A_NFC added to the polymer PLA to achieve better resistance of the bionanocomposite to scratching was determined. The best resistance of the prepared bionanocomposite to scratching was achieved by the addition of a 2.5 % A_NFC to the PLA polymer, which also has minimal reduced transparency with respect to the PLA film. With the highest addition of A_NFC to the PLA polymer, bionanocomposite films with minimal reduction of transparency were obtained. Cilj študije je bil priprava bionanokompozita na osnovi polimlečne kisline (PLA) z dodatkom nanofibrilirane celuloze (NFC) kot ojačitvene komponente. Za izdelavo kompozita smo uporabili nemodificirano in acetilirano NFC (A_NFC). NFC, posušeno z zamrzovanjem, smo acetilirali v heterogenem sistemu z acetanhidridom v dimetilformamidu (DMF) ob prisotnosti piridina kot katalizatorja. Uspešnost acetiliranja smo ugotavljali z infrardečo (FT-IR) spektroskopijo. Pripravili smo PLA filme z 2,5 %, 5 % in 10 % dodatkom nemodificirane oziroma acetilirane NFC. Osredotočili smo se na proučevanje vpliva dodatka NFC na prosojnost bionanokompozita in na njegovo odpornost proti razenju. Prosojnost bionanokompozitnega filma smo merili z UV-Vis spektrofotometrijo, odpornost površine filmov proti razenju pa smo ovrednotili z vzmetnim svinčnikom. Določili smo optimalno količino dodane NFC in A_NFC polimeru PLA za doseganje boljše odpornosti proti razenju. Ugotovili smo, da z dodatkom 2,5 % A_NFC dosežemo najboljšo odpornost pripravljenega bionanokompozita proti razenju, ki ima tudi minimalno zmanjšano prosojnost glede na PLA film. Celo z najvišjim dodatkom A_NFC k PLA polimeru smo dobili bionanokompozitne folije z minimalnim zmanjšanjem prosojnosti

The development of a simple surface barrier discharge plasma device is presented to enable more widespread access to and utilization of plasma technology. The application of the plasma device was demonstrated for pretreatment of wood prior to application of protective coatings for outdoor usage. The coatings' overall performance was increased, showing a reduction or absence of cracking due to weathering on plasma-pretreated specimens. Moreover, after ten months of outdoor weathering, the plasma-pretreated specimens showed fewer infections with biotic factors and improved adhesion performance in cross-cut tests, while the surface gloss performed independently from plasma pretreatment. In contrast to that, plasma-pretreated specimens were slightly more prone to discoloration due to outdoor weathering, whereas the plasma pretreatment did not impact the initial color after coating application. Graphic abstract

Due to their strong renewal power, the invasive tree species are spreading rapidly, especially in abandoned agricultural and forest areas and along traffic routes and water courses. One way of their restriction is the promotion of their use. In our research, we investigated surface finishing of wood of five selected invasive species in Slovenia, Box elder (Acer negundo L.), Black locust (Robinia pseudoacacia L.), Horse-chestnut (Aesculus hippocastanum L.), Honey locust (Gleditsia triacanthos L.) and Chinese sumac (Ailanthus altissima (Mill.) Swingle), and compared it with the finishing of the European beech (Fagus sylvatica L.) wood. For coatings, we selected one-component waterborne finish on acrylate-polyurethane basis, one-component solventborne finish on polyurethane basis and tung oil as a natural finish. Several surface properties were investigated. We proved that surface hardness, resistance to impact and adhesion were very much related to interactions between the coating and the substrate, while resistance to cold liquids was only dependant on the type of the finish. It was also shown that, in general, finishing of woods of selected invasive tree species was not problematic. The only exception was Black locust wood on which tung oil cured very slowly., Invazivne vrste drva brzo se šire zbog izrazito jakog svojstva obnavljanja, posebice na zapuštenim poljoprivrednim i šumskim površinama te uz prometnice i vodotokove. Jedan od načina ograničavanja njihova širenja jest poticanje uporabe njihova drva. U ovom smo istraživanju proučavali površinsku obradu pet invazivnih vrsta drva u Sloveniji: negundovca (Acer negundo L.), bagrema (Robinia pseudoacacia L.), divljeg kestena (Aesculus hippocastanum L.), gledičije (Gleditsia triacanthos L.) i pajasena (Ailanthus altissima (Mill.) Swingle), u usporedbi s površinskom obradom bukovine (Fagus sylvatica L.). Kao premazni materijali upotrijebljeni su jednokomponentni vodeni lak na bazi poliakrilata i poliuretana, jednokomponentni otapajući poliuretanski lak i tungovo ulje kao prirodni premazni materijal. Pritom je ispitivano nekoliko svojstava površine. Dokazano je da tvrdoća površine, otpornost na udarce i adhezija izrazito ovise o međudjelovanju premaza i podloge, a otpornost na hladne tekućine ovisi samo o vrsti premaza. Također je dokazano da površinska obrada promatranih invazivnih vrsta drva nije problematična. Izuzetak je drvo bagrema, na kojemu se tungovo ulje vrlo sporo suši.

Staining of wood with various substances and processes is an important part of surface finishing of wood. Colour differences as a result of staining and of exposure of coloured wood during its utilisation are usually evaluated by instrumental measurements. However, the measurement results can show something else compared to what our naked eye can see. Due to inhomogeneity of wood, this discrepancy can be even greater in the case of finished surfaces. The aim of our research was to evaluate distinctions between visual perception and numerically determined colour differences on differently finished wooden surfaces, to get information at which starting point the colour difference becomes visible, and to establish whether it is related to the nature of the surface. We established that the visual assessment is influenced by many factors and that there is a correlation between visual and instrumental assessments. The colour difference ΔE* of 0.5 should be considered as a value when it starts to become visible, and at the value of 2.0, observers already considered the colour difference as a different colour. It was stated that we have some tolerance in perceiving the colour change. This tolerance is more expressed in the case of transparent coating systems., Premazivanje drva različitim sredstvima i primjenom različitih postupaka važan su dio površinske obrade drva. Promjene boje kao rezultat premazivanja i izlaganja obojenog drva tijekom njegove uporabe obično se mjere uređajima. Međutim, izmjereni rezultati pokazuju nešto sasvim drugo od onoga što se vidi ljudskim okom. Kad je riječ o površinskoj obradi drva, razlike između izmjerenih rezultata i onoga što se vidi ljudskim okom mogu se povećati zbog nehomogenosti drva. Cilj istraživanja bio je procijeniti razlike između vizualne procjene i izmjerene promjene boje na površinski obrađenom drvu primjenom različitih tehnika kako bi se utvrdila vrijednost pri kojoj je promjena boje vidljiva te kako bi se utvrdilo ovisi li ona o vrsti površine. Ustanovili smo da na vizualnu procjenu promjene boje utječe velik broj čimbenika i da postoji veza između vizualne procjene i izmjerenih vrijednosti promjene boje. Promjena boje ΔE* od 0,5 vrijednost je pri kojoj promjena boje postaje vidljiva, a promjenu boje od 2 promatrači vide kao različitu boju. Uočeno je da postoji određena tolerancija u percepciji promjene boje, koja je veća pri procjeni promjene boje prozirnih sustava premaza.

A relatively new approach for wood protection against fungal decay is based on hydrophobization of wood and on lowering its moisture content. Water repellence of wood can be increased by polymerization of hydrophobic monomers in wood cell walls. It was found that Norway spruce wood after treatment with octadecyltrichlorosilane exhibited reduced water uptake by the wood cell walls, lowered water vapour sorption, and significantly increased dimensional stability of wood in terms of anti-swelling efficiency. Hydrophobicity and lower equilibrium moisture content were shown to cause increased resistance of the treated samples against brown-rot decay and molds.

We have produced hybrid liquefied-wood-based polyurethane (LW-PU) and LW-PU/nanosilica hybrid coatings for wood substrates. The prepared hybrid polyurethane coatings were hydrophobized by self-assembled monolayers of orthotrichlorosilane (OTS) via a sol–gel dipping process. The nanosilica addition into the LW-PU system enhanced the physical properties of coatings like surface hardness and stability toward cold liquids. The OTS hydrophobized coatings were characterized by Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thermogravimetric analysis (TGA). The surface became hydrophobic as the contact angle (CA) for the water droplet on a modified hybrid coating was ∼115° and very stable. The FTIR, SEM, and EDS analysis confirmed the formation of OTS monolayers on hybrid coatings.

Microwaves are very effective at wood pest eradication. However, elevated temperatures may pose a risk of damaging surface coatings used on cultural and historical artefacts. Therefore, we monitored changes in patterns of the original paint taken from such objects along with newly prepared coatings. We evaluated visual, mechanical, and chemical modifications of coatings when exposed to microwaves (750W, 2.4GHz), at 60°C or 80°C for 10 min. Whether old or new, only water-based coatings have proven to be resistant to elevated temperatures and no damage was observed at 80°C. Blisters have formed on layers of new oil paints and natural resins due to insufficiently cured film. Temperatures above 80°C may cause melting of coniferous wood resin and thus transport of resin to the surface on the other hand, temperatures up to 60°C are completely harmless. Mechanical and chemical changes of coatings exposed to microwaves were not observed, but the studies showed that colour and gloss exhibited minor changes. Mikrovalovi so zelo učinkoviti pri zatiranju lesnih škodljivcev. Lahko pa povišane temperature pomenijo tveganje za nastanek poškodb površinskih premazov, uporabljenih na kulturnozgodovinskih predmetih. Zato smo spremembe spremljali na vzorcih originalnih premazov, odvzetih s kulturnozgodovinskih predmetov, ter na novo pripravljenih premazih. Ocenili smo vizualne, mehanske in kemične spremembe premazov, izpostavljenih mikrovalovom (750W, 2,4 GHz) pri 60 °C ali 80 °C za 10 min. Stari premazi in novi, a le tisti na vodni osnovi, so se izkazali odpornejši proti povišanim temperaturam in poškodb pri 80 °C nismo opazili. Poškodbe v obliki mehurjenja so nastajale pri slojih nove oljne barve in naravnih smol, kot posledica premalo utrjenega filma. Temperatura nad 80 °C lahko povzroči taljenje smole v lesu iglavcev in tako prodiranje na površino vzorca pod premaz, medtem ko so temperature do 60 °C povsem neškodljive. Mehanskih in kemičnih sprememb premazov, izpostavljenih mikrovalovom, raziskave niso pokazale, sta pa se minimalno spremenila barva in sijaj.

Different natural drying oils were used for surface finishing of common beech wood (Fagus sylvatica L.). Surface performances and properties of the oiled surfaces were investigated according to the standard tests. Drying time, colour and gloss changes, uptake of oils into wood and uptake of liquid water into oiled wood, were determined, and the wettability of oiled wood surfaces was investigated by determination of the apparent contact angles of water. The results of the standard resistance tests showed that tung oil, the commercial decking and linseed oil had the best water repellent and protective properties. Worse properties were determined for those surfaces finished with walnut, hemp and coconut oils Za površinsko zaščito lesa navadne bukovine (Fagus sylvatica L.) smo uporabili različna naravna olja. Lastnosti premazanih površin smo proučili po različnih standardnih postopkih. Proučevali smo čas utrjevanja, spremembe barve in sijaja, navzem olj v les in navzem vode v oljen les, z meritvami navideznih kontaktnih kotov kapljic vode pa smo ocenili vodoodbojnost oljenega lesa. Rezultati standardnih preskusov odpornosti so pokazali, da imajo med olji, uporabljenimi v tej raziskavi, tungovo, komercialno olje decking in laneno olje najboljše vodoodbojne in zaščitne lastnosti. Slabše odpornostne lastnosti so bile ugotovljene pri površinah, premazanih z orehovim, konopljinim in kokosovim oljem

The aim of this study was to develop polymers in a liquid solution, from renewable bio-resources, usable as intermediate materials in the preparation of plastics, adhesives or coatings. The liquefaction of cork with glycerol was investigated at 150 °C, 180 °C, and 200 °C under acidic (sulphuric acid) or alkaline conditions (sodium hydroxide). Cork appears as a two-component material, containing suberin and lignocelluloses. In the presence of sulphuric acid, only the liquefaction of the lignocellulosic components was achieved, leading to liquefaction yield of less than 47% at all investigated conditions. The inverse phenomenon was observed with sodium hydroxide. Suberin was almost completely liquefied, but an increase of temperature and/or sodium hydroxide content was necessary to improve the liquefaction of lignocelluloses. Addition of polyethylene glycol to glycerol to a certain extent caused the conversion of suberin under acid conditions leading to liquefaction yield up to 93%. Therefore, it was demonstrated that it is possible to use cork dust, a less valuable by-product, for the production of various basic chemicals and/or polymers with a high added value.

Wettability of Norway spruce modified by a new vacuum thermal modification procedure was studied. The mass loss caused by this process ranged from almost 0% when treated at 140 °C to 4.3% at 210 °C. Apparent contact angles of water, formamide, and diiodomethane were measured by the Wilhelmy plate method on the specimens taken from the centers of the thermally modified wood samples. For the treatment at the highest temperature, the contact angle of water was significantly higher when compared to untreated spruce (96.6° vs. 83.6°); lower treatment temperatures, however, did not result in a clear correlation between treatment temperature and contact angle. Formamide yielded lower contact angles for treated spruce compared to the untreated one, but without clear influence of the treatment temperature and diiodomethane always gave perfect wetting. Surface energy calculations according to the Owens, Wendt, Rabel, and Kaelble method revealed that the thermal modification process in vacuum increased the surface f...

Waxes and wax emulsions are one of the most important solutions for non-biocidal wood protection. Wax treated wood is designed for outdoor use, therefore it is of considerable importance to elucidate the influence of weathering on the photodegradation processes. It is presumed, that wax treatment will reduce water uptake and thus reduce or slow down photodegradation processes. In order to test this hypothesis, three types of wax emulsions at two different concentrations were vacuum impregnated into Norway spruce wood specimens: an emulsion of montan wax (LGE), an emulsion of polyethylene (WE1) and an emulsion of oxidized polyethylene (WE6) wax. The samples were exposed to artificial accelerated weathering (AAW) for 500 cycles. Before and after AAW colour, the contact angle of water and moisture content were determined. Chemical and morphological changes at exposed surfaces were also investigated with FTIR spectroscopy and SEM. In parallel, the uptake of wax emulsions and water into the axial surfaces of samples was determined with a tensiometer. The moisture content measurements showed that the best hydrophobic effect was achieved with LGE treated wood, where the lowest colour and FTIR changes were observed as well. These results were supported by tensiometer measurements as well. Presented data clearly showed that high loadings of waxes reduce or at least slow down weathering. Among tested waxes, montan wax was found the most effective.

Two waterborne acrylic coatings were applied on spruce wood, impregnated with two copper-ethanolamine containing preservatives (CuE and CuEQ), one of them (CuEQ) containing a boron compound, octanoic acid and a quaternary ammonium compound as additives. Lower contact angles and deeper penetration of both coating types were observed on CuEQ treated, compared to untreated or CuE-treated wood. Improved adhesion of coatings on CuEQ impregnated wood was exhibited as well. In general, characteristics of surface finishes on copper-ethanolamine treated wood were comparable to untreated wood. It was also shown that copper leaching from the preserved wood was significantly reduced by application of the surface finishes.

International audience; Modification of wood can change its hydro- philic character. Consequently, modified wettability of wood can change its behavior with coating or gluing processes. The authors investigated the wettability of oil-heat-treated and DMDHEU-modified Scots pine wood with some commercial waterborne coatings. The increased hydrophobic character of modified wood was revealed from high advancing contact angles of water. In contrast, exterior waterborne coatings exhibited much better wetting on modified substrates than on unmodified substrates. Good wetting of modified wood by waterborne coatings is an interesting result, opening up possibilities for application of environmentally friendly waterborne surface systems on modified wood.

Liquefied wood-based polyurethane wood coatings of an aesthetically acceptable light colour were prepared and characterised. Liquefied black poplar wood was obtained by solvolysis in a polyethylene glycol/glycerol mixture, and it was bleached with hydrogen peroxide. The bleaching treatment converted liquefied wood from a dark brown to a yellowish product. Polyurethane films were prepared by the curing of liquefied wood with polymeric diphenylmethane diisocyanate or trimethylolpropane toluene diisocyanate prepolymer (TMP/TDI) isocyanate-type hardeners. It was found that the selected properties of the films prepared from the bleached liquefied wood were, in general, equivalent to those prepared from unbleached liquefied wood. The mechanical properties of the films obtained with the TMP/TDI curing agent were acceptable for wood coating applications. The initial poor resistance of the films to water and ethanol was substantially improved by the addition of n-octyltriethoxysilane to the liquefied wood prior to the preparation of the polyurethane coatings; the hardness of the films also increased.

Exterior coatings may not provide sufficient protection of wood against biodeterioration. In order to minimise the decay risk, wood can be impregnated with biocides before finishing. However, pretreatment of wood may have an effect on some important properties of surface coatings. The authors impregnated spruce wood specimens with a new preservative formulation, containing the ester of boric acid with an alkanolamine. The aim of this research was to establish a possible influence of this biocide on the performance of acrylic and alkyd stains on pre-treated wood. They studied the drying characteristics, stackability, adhesion, and permeability of the coatings. A boron-based preservative in a treated spruce wood had a pronounced influence on the drying of coatings and on the permeability of the acrylic stain. However, the influence on adhesion of the coatings was only indicated.

The appearance of age or the so-called patina of cherry wood and spruce wood was obtained by treatment with ethanolamine vapours. Chemical changes in the treated wood were investigated by FT-IR spectroscopy, electron paramagnetic resonance and nitrogen content analysis. It was shown that the use of aggressive and toxic ammonia could be replaced by fuming with ethanolamine. Extensive colour stability experiments of patinated cherry wood that was coated with linseed oil varnish, linseed oil, beeswax or nitro-cellulose lacquer indicated that the described antiquing method represents a new possibility for producing various wood products with the appearance of age.

Preparation of polyurethane wood coatings based on copper-, chromium-, and boron (CCB) containing liquefied wood was performed, as an alternative way to manage postconsumed preservative-contaminated wood. Additionally, we examined the possibility of improvement of selected properties of the liquefied wood-based coatings by an addition of silica nanoparticles. The constituents of the CCB wood preservative do not exhibit an influence on a liquefaction process and on composition of the liquefied mixture. CCB also does not affect curing of the formulations containing liquefied wood and an isocyanate-type hardener. Furthermore, influence of CCB on adhesion strength of liquefied wood-based coatings on a wooden substrate, their hardness, and resistance to scratching and to water, acetone, and alcohol, is not exhibited. However, apart from these, from the applicative point of view, positive results, any improvement of the coating properties by the addition of silica nanoparticles is not shown. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40865.

The influence of viscoelastic thermal compression (VTC) on surface wettability and bonding performance of wood was evaluated. Low quality beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) were densified with the VTC process to different degrees of densification. Control and densified strips were bonded with phenol–formaldehyde (PF) adhesive and liquefied wood (LW). Shear strength of bonded assemblies was determined after 1 week of conditioning at 20 °C and relative humidity of 65 %. Wettability was determined on the basis of the contact angle of water, PF adhesive, and LW using the Wilhelmy method. Results showed that densification of beech and spruce wood did not significantly affect the shear strength of specimens bonded with PF adhesive. In beech assemblies bonded with LW shear strength decreased significantly with increased density, whereas in bonded spruce specimens decrease of shear strength was not significant. It was found that degree of densification and bonding process used in the study were not appropriately chosen for spruce wood specimens, since major deformations after the bonding process occurred. Wettability changed significantly after densification. Contact angle of water and LW increased after densification, whereas contact angle of PF showed inverse trend and decreased after VTC process. Furthermore, the degree of densification had a minor effect on the wettability.

This study aims to investigate the influence of atmospheric plasma treatment on the abrasion resistance of particleboards, as an example of a wood-based material, coated with a waterborne finish. The treatment of the substrate, prior to coating application, using a floating-electrode dielectric barrier discharge (FE-DBD) plasma, resulted in an enhanced abrasion resistance of the coated particleboards in comparison to the untreated ones during the abrasion test with a duration of 200 revolutions. This finding was related to lower contact angles of water and coating after treatment with plasma and greater hardness of the coating on the treated substrates. The micrographs of the sample cross sections recorded with scanning electron microscope showed differences in the amounts of remained coating on the abraded areas. Investigation with attenuated total reflection Fourier transform infrared spectroscopy revealed that treatment of the substrate with plasma did not affect the chemical composition nor the curing and structure of the later applied coating. Further studies should be performed to determine the resistance properties of such surface systems to other impacts., Cilj ovog rada bio je istražiti utjecaj atmosferske plazme na otpornost iverica na abraziju, kao primjer materijala na bazi drva premazanoga vodenim premazom. Tijekom ispitivanja abrazije u trajanju od 200 ciklusa obrada iverica uz pomoć plazme (FE-DBD) prije nanošenja premaza rezultirala je poboljšanom otpornošću premazanih iverica na abraziju u usporedbi s neobrađenom ivericom. Rezultat istraživanja povezan je s nižim kontaktnim kutom vode i premaznog materijala nakon obrade iverica plazmom i s većom tvrdoćom premaza na podlozi obrađenoj plazmom. Mikrografi je presjeka uzorka dobivene pretražnim elektronskim mikroskopom pokazale su razlike u količini preostalog premaza na površinama ispitanima na otpornost na habanje. Ispitivanje infracrvenom spektroskopijom uz prigušenu totalnu refleksiju pokazalo je da obrada podloge plazmom nije utjecala na kemijski sastav ni na otvrdnjavanje i strukturu kasnije nanesenog premaza. Potrebno je provesti daljnja ispitivanja kako bi se dodatno utvrdila otpornost takvih površinskih sustava.