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Olja se uporabljajo za obdelavo površin lesa v notranji in zunanji uporabi. Če jim dodamo pigmente, lahko z njimi dosegamo dodatne vizualne učinke, kot so rustikalen izgled, poudarjanje lesnih por, obenem pa povečamo zaščitno sposobnost premaza proti fotodegradaciji lesne podlage. V naši raziskavi smo namesto klasičnih pigmentov uporabili naraven in obnovljiv vir, utekočinjen les (UL), ki smo ga v dve olji vmešali v dveh razmerjih. Tako pripravljene mešanice smo nanesli na vzorce bukovega in jesenovega lesa. Po nanosu smo najprej spremljali hitrost sušenja, po osušitvi pa smo določili še odpornost površin proti hladnim tekočinam ter suhi toploti. Površine smo tudi izpostavili pogojem umetnega staranja pod ultravijolično (UV) svetlobo in s tem preverili, kakšno vlogo pri tem igra dodatek UL. Barvne razlike smo določili z meritvami barve pred premazovanjem in po njem ter po izpostavitvi UV svetlobi. Naša raziskava je potrdila, da je UL kompatibilen s tungovim in Bio impregnol WM oljem, ter se posledično lahko uspešno uporablja za njuno za njuno obarvanje. Potrdili smo tudi, da dodajanje UL v tungovo olje ne vpliva na odpornost tako premazanih površin proti hladnim tekočinam in niti ne na odpornost površin obeh olj proti suhi toploti. Žal pa dodajanje UL v olja upočasnjuje hitrost sušenja. Dodatno smo tudi ugotovili, da z UL obarvani premazi niso najbolj fotostabilni.

After wood has been coated and exposed to external climatic conditions and/or elevated temperatures, staining of the coating film by hydrophilic and lipophilic extractives may occur where knots are located. For this reason, the knot staining resistance of the coating system is very important. In our study, we tested some basic types of white pigmented systems. In doing so, we adapted the method SIST EN 927-7:2020 according to our capabilities, optimized it and critically evaluated whether there is room for improvement of the standardized method. The results of our research showed that the knot staining resistance of coating systems is related to the type of solvent in the coatings, the hiding power of the system and its build-up or dry film thickness. Accordingly, solvent-borne coatings were found to be better, as were those containing more pigments and those with a higher dry film thickness. We have also found that by evaluating the colour difference on the regions with and without knots before exposure and accounting for this in evaluation of colour differences after exposure, we can make a much more objective classification of coating systems according to their effectiveness against knot staining. Based on this finding, we believe that the standardized method needs to be corrected accordingly.

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.

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 sylvatica L.) 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.

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.

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 dimethylformamide (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 bionanocomposite to scratching. The transparency of the bionanocomposite film was measured using UV-Vis spectrophotometry, 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.

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.