Fanni Fodor

The present study investigated, for the first time, the synergistic effects of combining bark extractive impregnation with ammonia fuming, revealing promising enhancements in both the aesthetic and functional attributes of wood. This combined approach uses the bioactive and protective properties of natural extractives while also making ammonia fuming effective for wood species with low extractive content. Bark extracts of pedunculate oak (Quercus robur L.) and European beech (Fagus sylvatica L.) were investigated on wood specimens of European beech (with and without red heartwood), hornbeam (Carpinus betulus L.), and gray poplar (Populus × canescens). Oak bark extract contained substantially higher total extractives and polyphenols than beech bark extract. Treatments caused only minor changes in density and equilibrium moisture content (generally within ±8%), while some shrinkage parameters changed more noticeably. The largest improvement occurred in beech false heartwood, where volumetric shrinkage decreased by up to 16%. Both treatments darkened the wood surface, with oak bark extract producing significantly larger color changes; ammonia fuming further intensified these effects, especially in poplar. Durability improved markedly: mass loss caused by Coniophora puteana (Schumach.) P. Karst. and Trametes versicolor (L.) Lloyd decreased from 27%–38% in untreated samples to 0.58%–7.73% after treatment, improving durability classification from Durability Class 4 to classes 1–2. Bark extract treatments slightly reduced hardness but generally maintained or slightly increased compression strength.

Wood modification using biopolymers has emerged as a sustainable alternative to conventional chemical treatments, enhancing wood’s durability, moisture resistance, and mechanical properties while reducing environmental impact. This review provides a comprehensive overview of the latest advancements in biopolymer-based wood modification, focusing on commonly used biopolymers such as furfuryl alcohol, polylactic acid, caprolactone, polybutylene adipate terephthalate, polybutylene succinate, zein, lignin, tannin, chitosan, alginate, gums, fatty acids, rosin, and sorbitol + citric acid. Future perspectives highlight the need for interdisciplinary collaboration between academia, research institutions, and industry to accelerate innovation and commercialization. This review aims to provide valuable insights for researchers and industry professionals working toward the development of high-performance, eco-friendly modified wood products.

This research aimed to examine the effects of a deep impregnation technique (Royal process) and surface coating using a linseed oil-based product, enhanced with small amounts of brown and grey pigments, on the natural and artificial weathering of wood. The treated and reference samples underwent natural weathering for five years and artificial weathering for 1900 h. Changes in color and surface roughness were assessed during weathering. For the artificially weathered samples, liquid water absorption was measured both before and after exposure. The impregnated and coated samples gradually lost their brown color, turning grey over time. More pronounced differences were observed during natural weathering, with the coated samples showing greater structural changes on the wood surface. In contrast, impregnated samples slowed down structural alterations compared to the reference samples. Both treatments effectively reduced water absorption before weathering, although this effect diminished after exposure. The treatments did not significantly impact the fire resistance of spruce and beechwood.

The application of tree of heaven (Ailanthus altissima (Mill.) Swingle) is constrained by its poor durability and dimensional stability. Despite exhibiting promising physical and mechanical properties comparable to ash wood (Fraxinus excelsior L.), it is regarded as an invasive species and receives limited attention in wood property enhancement research. This study subjected tree of heaven to heat treatment at 180 °C and 200 °C to investigate its sorption characteristics using dynamic vapor sorption tests. The results revealed a 13% reduction in equilibrium moisture content at 95% relative humidity and 25 °C after thermal modification at 180 °C and a 25% reduction after thermal modification at 200 °C. Increasing the treatment temperature lowered the moisture content ratio to 0.76 and shortened the conditioning time by up to 10%. The highest hysteresis, ranging from 3.39% to 3.88%, was observed at 70% relative humidity.

In this research, acetylation was applied under industrial conditions to improve the properties of Turkey oak and Pannonia poplar wood. Both species are potential “climate winners” in Hungary, yet they are currently underused due their low durability and poor dimensional stability. The acetylation modification process may be a suitable method to improve their properties. In order to verify the effectiveness of the process, comparative chemical analyses (cellulose, hemicelluloses, lignin, extractives, ash, buffering capacity, and pH) of the untreated and acetylated heartwood and sapwood were carried out for both species for the first time. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was also used to support the evaluation of the chemical analyses. The weight percent gain was 11.54% for poplar and 0.94% for Turkey oak, indicating poor treatment efficiency for the latter. The cellulose, hemicelluloses, and lignin contents changed significantly in poplar, with the highest change (+81%) induced by acetylating the hemicelluloses. Only the alpha-cellulose content decreased significantly in Turkey oak, presumably due to the degradation of the non-crystalline part of the cellulose. Acetylation may improve the resistance of Pannonia poplar against moisture, weather, decay, and wood-boring insects, but the process parameters need to be optimized in order to prevent degradation and discoloration in poplar. Turkey oak was found to be less suitable for acetylation due to its low permeability and tendency to crack.

Jelen kutatásban irodalmi feldolgozást nyújtottunk a közönséges gyertyánról, mely egy őshonos, számos kedvező tulajdonsággal is rendelkező, nem elhanyagolható fakitermelési lehetőséget nyújtó, de iparban kevésbé hasznosított fafaj. Megállapítottuk, hogy habár a faanyaga természetes formájában nem tartós, ugyanakkor az egyik legsűrűbb, legkeményebb, és legkopásállóbb fafaj Európában. Kedvezőtlen tulajdonságai miatt többnyire tűzifaként hasznosul. Beltéri felhasználási területeit új használati eszközökkel, burkolati elemekkel, és dekorációs elemekkel lehetne bővíteni, emellett különböző, környezetbarát famodifikációs eljárásokkal egy sokkal tartósabb és ellenállóbb faanyag kapható, melynek színét a kezelési beállítások variálásával alakíthatjuk a felhasználó igényeire. Ez az anyag felhasználható kültéri fatermékekhez, de akár építészeti célú alkalmazásra is. A gyertyán hazánkban középtávon stabilan rendelkezésre áll, és lehetőséget nyújthat tartós fatermékek előállítására, amennyiben meglenne rá a feldolgozó és a fizetőképes kereslet a hatékony szállítási távolságon belül. A kutatás végén a megállapításokat egy Gyengeségek-Erősségek-Lehetőségek-Veszélyek elemzéssel összegeztük.

The present study aimed to determine how acetylation affected the bonding properties of European hornbeam wood. The research was supplemented with the investigation of wetting properties, wood shear strength, and microscopical studies of bonded wood, as these all have strong relationships with wood bonding. Acetylation was carried out on an industrial scale. Acetylated hornbeam showed a higher contact angle and lower surface energy than untreated hornbeam. Although the adhesion of the acetylated wood surface is lower due to its lower polarity and porosity, the bonding strength of acetylated hornbeam was similar to that of untreated hornbeam when bonded with PVAc D3 adhesive, and it was higher in the case of PVAc D4 and PUR adhesives. Microscopical studies proved these findings. After acetylation, hornbeam could be used in applications where it is exposed to moisture, as its bonding strength after soaking or boiling in water was significantly higher than that of untreated hornbeam.

This test aimed to discover if industrially acetylated hornbeam can tolerate real-field conditions in Hungary, where various microorganisms can attack the wood separately or cooperatively. Untreated samples accompanied the modified wood to assess the degradation capacity of the soil. The test also focused on weather parameters, the Scheffer index, and soil properties. The untreated stakes showed insect damage, soft rot decay, white rot decay, wasp stripping, moss, and cracks. All of the beech and hornbeam stakes broke after 3.5 years, and the last Scots pine sapwood stakes broke after 6 years. To date, acetylated hornbeam exhibits stronger resistance than untreated hornbeam, beech, and Scots pine sapwood. The acetylated hornbeam stakes showed no decay after 6 years of exposure, and they became dry shortly after being taken from the soil. Acetylated hornbeam stake number 7 had superficial brown rot decay after 18 months, which gradually worsened over the years. The Fourier transform infrared spectroscopy analysis revealed that this stake had lower acetyl content. It was associated with hornbeam wood; it had a wet pocket or a part that was not as permeable and achieved a lower grade of acetylation.

Nine different environmentally friendly coatings were tested on natural and acetylated hornbeam wood, during natural weather exposure and xenon lamp irradiation. The coating performance of acetylated hornbeam, and the photostability properties of tested coatings were evaluated to offer suggestions regarding suitable and less-suitable coatings for the exterior use of acetylated hornbeam. On the one hand, acetylation decreased the coating absorbance of hornbeam. On the other hand, it made the wood more durable and dimensionally stable, all of which influences the outdoor performance of acetylated hornbeam. The color of acetylated hornbeam is not photostable; it brightens during photodegradation, and greys after leaching. For long-lasting color, acetylated hornbeam should be coated with dark pigmented stains and maintained regularly. Fungal degradation and cracking did not occur, but the wood is just as susceptible to wasp stripping as untreated hornbeam. In this study, 200-h-long xenon lamp irradiation resulted in a color similar to that caused by 1 month of weather exposure (April to May 2018, Sopron, Hungary).