Articles

WOOD RESEARCH Volume 70, Number 4, 2025
RENÁTA KUTLÁKOVÁ, PETER RANTUCH, JOZEF MARTINKA, MARGARÉTA TIBENSKÁ, TOMÁŠ ŠTEFKO, and IGOR WACHTER

CHARACTERIZATION OF IGNITION PROCESS OF THERMALLY TREATED WOOD BY CONE CALORIMETER

This study examines the influence of thermal treatment on the ignition properties of Norway spruce (Piceaabies (L.) H. Karst.) and sessile oak (Quercus petraea (Matt.) Liebl.) wood. Using a cone calorimeter both untreated and thermally modified samples (180°C for 6 h) were analysed to determine key fire modelling parameters: combustion efficiency, critical heat flux, ignition temperature, thermal inertia, and thermal response parameter. Obtained results reveal that thermally treated wood exhibits higher combustion efficiency than its untreated equivalent, with spruce generally outperforming oak. The effect of thermal treatment on other properties was species-dependent. Thermally treated spruce showed an increase in critical heat flux and a decrease in both thermal inertia and the thermal response parameter. Conversely, thermally treated oak displayed a reduction in critical heat flux and an increase in both thermal inertia and the thermal response parameter. These results highlight the complex, species-specific effects of thermal modification on the fire behaviour of wood.

WOOD RESEARCH Volume 70, Number 4, 2025
DUŠAN JOKANOVIĆ, VESNA NIKOLIĆ JOKANOVIĆ, JOVANA PETROVIĆ, MARKO MARINKOVIĆ, BOJAN TUBIĆ, ANDREJA LAZOVIĆ, and FILIP JOVANOVIĆ

MORPHO-ANATOMICAL TRAITS OF QUERCUS CERRIS AND Q. RUBRA ONE-YEAR-OLD SEEDLINGS CULTIVATED IN DIFFERENT CONTAINER TYPES

The paper investigated the variability of the morphological-anatomical traits of one-year-old oak seedlings (Quercus cerris L. and Quercus rubra L.) produced in three different container types (Hiko, Plantagrah, biodegradable). A two-factorial ANOVA showed for the morphological characteristics (root collar diameter and height) statistically significant difference between the species and between the containers, too. The interaction between the variability factors (container type and species) also affects height and root collar diameter. As for the obtained results of two-factorial ANOVA for anatomical parameters (wood, bark, pith proportion, and vessel width), statistically significant differences were obtained for all of them between species, as well as between container types. On the other hand, the interaction of container type and species does not affect vessel width and bark content unlike wood and pith proportion. Comparing the species, it can be concluded that the average values of all traits, apart from vessel width, are higher in Q.rubra L. The largest dimensions of all elements regardless of the species were obtained for Hiko, then Plantagrah, and the smallest for biodegradable container.

WOOD RESEARCH Volume 70, Number 4, 2025
VLADIMÍR KUŇA and JOZEF BALBERČÁK

THE INFLUENCE OF PULP BEATING AND PAPERMAKING AGENTS ON THE CHARGE DENSITY OF FIBERS AND COLLOIDAL PARTICLES IN PAPERMAKING WATERS

The first part of the paper is focused on monitoring the impact of the beating process on the charge density of fibres and colloidal particles in water in the production of tissue papers. Three types of pulps most commonly used were tested: long-fibre pine pulp, short-fibre eucalyptus pulp and short-fibre hardwood birch pulp. In the range of beating degrees from 14°SR to 35°SR, the impact of beating on the charge density of fibres expressed as Zeta potential, the charge density of colloidal particles expressed as PCD value and the conductivity of the paper suspension were evaluated. The paper also evaluates the impact of beating on the physical and mechanical properties of laboratory sheets. The second part of the paper is focused on monitoring the impact of papermaking aids, in the production of tissue papers, on the charge density of fibres and colloidal particles in water. The most significant impact was demonstrated by the agent for increasing the wet strength of paper. In these laboratory tests, pulp mixtures were used that were prepared by separately beating individual pulps to a beating degree of 25°SR.

WOOD RESEARCH Volume 70, Number 4, 2025
QINYI GU, HONGHAI LIU, and TAO LI

THE STUDY OF SURFACE DENSIFICATION AND TEMPERATE SUPERHEATED STEAM MODIFICATION FOR RUBBERWOOD

This study aimed to develop a high-value wood composite by surface-densification combined with temperate superheated steam modification technology. Rubberwood boards were hot-pressed, the impact of the peak density and thickness of densified layer on the physical and mechanical properties of wood were studied. In this study the platen temperature was kept constant, after hot-pressing the platen cooling phase was omitted replaced by special compression pressure decreasing and steam discharging technic, which could save much energy and time. Superheated steam treatment (190°C for 1.5 h) and conditioning (110°C for 2 h) were recommended for improving dimensional stability and durability. Study results indicated that the surface hardness and modulus of rupture of surface-densified followed by superheated steam modified rubberwood increased by 55.9% and 41.6% compared with non-densified one respectively. Dimensional stability improved substantially. The durability was improved to ‘durable class’ according to GB/T 13942.1-2009.

WOOD RESEARCH Volume 70, Number 4, 2025
EMRE BIRINCI

INVESTIGATION OF THE EFFECT OF EXTREME TEMPERATURE ON SCREW DIRECT WITHDRAWAL RESISTANCE OF WOOD PLASTIC COMPOSITE DECKING PROFILES

In this study, the effects of extreme temperatures on screw direct withdrawal resistance (SDWR) of wood plastic composite (WPC) decking profiles were systematically investigated. Commercially produced WPC decking profiles were tested at different temperature levels (-40°C, -20°C, 0°C, room temperature, +40°C and +60°C); their effects on SDWR were evaluated by controlling parameters such as screw diameter (3.0 mm and 3.5 mm) and pilot hole diameter (60%, 70% and 85%). Additionally, the relationships between Shore D hardness and SDWR measured at each temperature level were revealed through statistical analyses. The results show that as the temperature increases, Shore D hardness decreases and accordingly, significant decreases occur in SDWR. The highest SDWR was obtained at -40°C temperature, 60% pilot hole ratio and 3.5 mm screw diameter combination. This highlights the influence of material hardness and screw-material interaction on joint performance. According to Pearson correlation analysis, a strong and statistically significant (r=0.939, p=0.0055) positive relationship was determined between Shore D hardness and SDWR.

WOOD RESEARCH Volume 70, Number 4, 2025
YANG ZHENG, MENGQING KE, CHENYANG CAI, XIAO ZHONGYANG, and HONGHAI LIU

COMPARATIVE STUDY ON THE HEAT TREATMENT OF DALBERGIA LATIFOLIA ROXB. WOOD UNDER ATMOSPHERIC PRESSURE AND VACUUM CONDITIONS

This study comparedatmospheric heat treatment (AHT) and vacuum heat treatment (VHT)of Dalbergia latifoliaRoxb. at 180°C for 6 hto improve dimensional stability. Through multiple tests, it analyzed their effects on the wood. Results showed VHT caused milder chemical changes, preserving hydroxyl and lignin structures while AHT severely degraded hemicelluloses. VHT led to lower weight loss 0.45% vs 1.25%, better dimensional stability with a greater reduction in radial swelling 0.84% vs 1.34%, higher mechanical strength (modulus of rupture: 118.22 MPa vs 95.83 MPa; modulus of elasticity 9361.50 MPa vs 8558.34 MPa), and a smaller color change ΔE*: 9.79 vs 18.65. Overall, VHT can balance performance improvement and minimize damage to the wood’s structure and aesthetics.

WOOD RESEARCH Volume 70, Number 4, 2025
MIKKEL NÜSSLER, JOHN BANG MATHIASEN, and JACOB KJÆR ESKILDSEN

DECAY RESISTANCE AND FIRE CLASSIFICATION OF SURFACE-CARBONIZED SCOTS PINE WITH POST-CARBONIZATION LINSEED OIL AND SODIUM SILICATE TREATMENT

Todetermine the effect on decay resistance and fire classificationof applying linseed oil or a sodium silicate solution to surfacecarbonized Scots pine,two different experiments were conducted. AnAWPA E10 standard (AWPA 20216) soil block test was conducted to determine the decay resistance of eight unique treatment configurations, and fireclassification following the EN 13823:2010+A1:2014 / EN 14915:2013was conducted to determine the fire classification of façade panels treated with pure linseed oil and a 40/60 mix of linseed oil and sodium silicate respectively. The study showed that decay resistancemeasured as average mass loss (AML%) improves significantly by surface carbonization butdepends on the intensity of the treatment as well as the application of surface sealing substances applied post-carbonization. Carbonized Scots pine façade panels without any post-carbonization treatment as well as carbonized Scots pine treated with sodium silicate or a 40/60 mix of linseed oil and sodium silicate solution obtained an EN 13823:2010+A1:2014/ EN 14915:2013 B-s1,d0 fire classification. Carbonized Scots pine treated with pure linseed oil did not obtain any classification under EN 13823:2010+A1:2014/ EN 14915:2013.

WOOD RESEARCH Volume 70, Number 3, 2025
MATEUSZ SZAR, JAROSŁAW KOZAK, BEATA SIEKIERKA, WOJCIECH SPISAK, GRZEGORZ BOCZKAL, ŠTEFAN BOHÁČEK, DANIELA MAJERČÁKOVÁ, and ANDRZEJ CHLEBICKI

ROCK-CELLULOSE COMPOSITES IN SOIL VENTILATION DUCTS FOR COMPACTED SOILS. Short notes

Soil Ventilation Ducts (SVDs), produced from a rock–cellulose composite was prepared by mixing short-fibre cellulose with granite gravels, compressed into cylindrical briquettes. The SVDs were tested in compacted soil (compaction > 2.1 MPa) to assess their effect on water infiltration dynamics. The results confirmed the efficiency of SVD in enhancing soil water infiltration both under natural rainfall conditions and in controlled experiments increasing the volumetric water content from 35% to nearly 70%, while no change was observed in the control. Additionally, results from a controlled experiment demonstrate that the application of SVD substantially enhanced water infiltration. Registered absorption time of 4.7 litres of water on surface area of 615.75 cm² was 1440 min for the control (without SVD), 14.5 min at 15 cm SVD length, 2.5 min at 30 cm SVD length, and 2 min at 45 cm SVD length, indicating a strong positive relationship between SVD length and infiltration efficiency.

WOOD RESEARCH Volume 70, Number 3, 2025
VERONIKA KVORKOVÁ, IGOR WACHTER, TOMÁŠ ŠTEFKO, PETER RANTUCH, DÁVID KOPINEC, and JOZEF MARTINKA

THE IMPACT OF ACRYLIC RESIN ON THE PERFORMANCE OF SPRUCE AND FIR WOOD: THE STUDY OF HARDNESS, WATER ABSORPTION, AND NATURAL WEATHERING

This study investigated the effects of acrylic resin stabilization on the properties of Norway spruce (Picea abies, (L.) H. Karst) and European silverfir (Abies alba, Mill) wood. The primary focus was on enhancing durability by improving hardness, water resistance, and UV resistance. Results demonstrated a significant increase in hardness (D-Shore) for both species, with spruce exhibiting a 72.3% improvement and fir showing a 16.5% enhancement. Water absorption tests revealed a substantial decrease in water uptake for stabilized samples compared to untreated controls. However, colorimetric analysis indicated a slight decrease in UV resistance for stabilized samples, likely attributed to the lack of UV stabilizers within the acrylic resin.

WOOD RESEARCH Volume 70, Number 3, 2025
KRISHNA GIRI, GIRISH CHANDRA, R.S.C. JAYARAJ, GAURAV MISHRA, and ELANGBAM NIRMALA CHANU

VOLUME ESTIMATION MODELS FOR QUERCUS SERRATA AND PINUS KESIYA USING NON-DESTRUCTIVE TECHNIQUES. A CASE STUDY FROM NORTHEAST INDIA

The accurate, non-destructive estimation of tree volume is essential for sustainable forest management, particularly in data-deficient regions like Manipur, Northeast India. This study developed species-specific regression models to estimate the over-bark stem volume of Quercus serrata and Pinus kesiya, based on the measurements from 108 trees per species across 29 sites. Diameter at breast height (DBH), total height, and sectional diameters were obtained using a Nikon Rangefinder and Criterion™ RD 1000 dendrometer. Smalian’s method was used to calculate the stem volume. Models using DBH alone and in combination with height were evaluated via model efficiency (EF), root mean square error (RMSE), and Akaike’s information criterion (AIC). For Q. serrata, the best models were an inverse quadratic (DBH only) and a third-degree polynomial (DBH and height). For P. kesiya, the best fits were logarithmic and quadratic, respectively. QQ plots confirmed the fit after logarithmic transformation. Residuals were normally distributed, and high EF confirmed model accuracy.

WOOD RESEARCH Volume 70, Number 3, 2025
MASAYA GEMMA, SATOSHI SAKAMOTO, and DAISUKE KOBAYASHI

DEFORMATION CHARACTERISTICS OF FIBERBOARD DUE TO THE LOCALIZED HEATING

In this study, we investigated the deformation characteristics of fiberboard used for the preparation of metal casting molds due to the localized heating caused by the high-temperature load. Through high-temperature heating experiments on fiberboards (MDF, LDF, HDF) and woods (White ash, Balsa, Ebony), it was revealed that the localized heating causes expansion and dent in the materials. The expansion is due to the behavior of moisture inside the material, and the dent is due to the deterioration of surface strength caused by pyrolysis of cellulose in the materials. We also clarified the effects of the physical properties and structure of the material on the height of expansion and the depth of dent.

WOOD RESEARCH Volume 70, Number 3, 2025
BARBAROS YAMAN, ALİ AKIN AKYOL, and HİKMET YAZICI

THE ANATOMY OF THE WOODS OF THE HISTORIC DARAN BRIDGE

This study presents the wood anatomy analysis of the historic Daran Bridge, a traditional wooden cantilever structure located over the Daran river (Sarıveliler, Türkiye), that has been in use since the 19th century. Two structural timber samples were examined microscopically using transverse, tangential, and radial sections. Anatomical features such as distinct growth rings, absence of normal resin canals, dentate torus in bordered pits of the tracheid walls, and cross-field pits with a piceoid to taxodioid shape led to the taxonomic identification of Cedruslibani L. (Taurus cedar). The species is native to Southern Anatolia, and the bridge is located within its natural distribution area. Physical and mechanical property analysis (e.g., density: 530 kg/m³; bending strength: 70–85 N/mm²) confirmed the wood’s high durability, strength, and suitability as a load-bearing element. Historically, the selection of Taurus cedar was based on its local availability and resistance to environmental degradation.

WOOD RESEARCH Volume 70, Number 3, 2025
Holta Çota, ENTELA LATO, DOKLEA QUKU, HEKTOR THOMA, and ERALD KOLA

The Effect of Heat Treatment on Compression Strength of Silver fir (Abies alba Mill.) and Ash Wood (Fraxinus angustifolia Vahl.). Short notes

This study investigates the effects of thermal modification on the compressive strength parallel to the grain of ash (Fraxinus angustifoglia Vahl.) and fir (Abies alba Mill.) wood. Specimens were thermally treated at 130°C, 180°C, and 220°C for durations of 2 and 8 h under atmospheric conditions. Mass loss increased with both temperature and time, with fir exhibiting greater loss than ash, up to 20.3% and 15.7%, respectively, at 220°C for 8 h. Compressive strength was influenced significantly by treatment intensity. Fir showed minor improvements at lower temperatures but experienced a reduction of up to 23.0% at the highest treatment. In contrast, ash displayed enhanced strength at 180°C (up to +15.1 %) and retained better mechanical performance at 220°C, with a maximum reduction of 11.3%. These findings demonstrate that heat treatment can both enhance and deteriorate compressive strength depending on the treatment severity, emphasizing the need to optimize thermal parameters for maintaining structural performance in wood applications.

WOOD RESEARCH Volume 70, Number 3, 2025
HARUNA SEIDU, LÁSZLÓ BEJÓ, and RÓBERT NÉMETH

COMPARATIVE ANALYSIS OF MOE AND MOR OF PF AND MUF-BONDED EUCALYPTUS PLYWOOD OF VARYING THICKNESS. Short notes

This study assesses the mechanical characteristics of eucalyptus plywood produced in Ghana, particularly focusing on how panel thickness (9–21 mm) and adhesive type (phenol formaldehyde (PF), and melamine urea formaldehyde (MUF) influence the modulus of elasticity (MOE) and modulus of rupture (MOR) of the panels. The panels were tested according to EN 310: 1993. The results indicate that mechanical strength and thickness are inversely correlated, with thinner panels exhibiting superior performance. MOR decreased from 59.85 N/mm² to 39.36 N/mm² for PF-bonded plywood, while longitudinal MOE declined from 7096 N/mm² (9 mm) to 4627 N/mm² (21 mm). Although their values were lower (from 6093 N/mm² to 4155 N/mm²), the MUF-bonded panels demonstrated comparable trends. Significant differences based on orientation were confirmed by ANOVA analysis (p < 0.01), showing that longitudinal samples significantly recorded higher values than transverse ones, particularly in thinner panels. Thicker panels exhibited less anisotropy due to stress homogenization, but PF adhesives provided greater mechanical stability compared to MUF.

WOOD RESEARCH Volume 70, Number 3, 2025
EUN-SUK JANG, GYEONG-TAEK LIM, and HEE-JUN PARK

IMPREGNATION EFFICIENCY OF FLAME RETARDANTS IN HINOKI CYPRESS (CHAMAECYPARIS OBTUSA) PLYWOOD USING THE VACUUM-PRESSURE METHOD. Short notes

This study aimed to investigate the effectiveness of vacuum-pressure impregnation for the flame-retardant treatment of hinoki cypress (Chamaecyparis obtusa) plywood. The effect of impregnation duration (50–75 min) on the solid content of flame-retardant impregnation (SCFI) was analyzed. The SCFI significantly increased with rising impregnation time, as demonstrated by analysis of variance and regression analysis. In addition, the outer regions of the plywood exhibited higher impregnation efficiency than the inner regions owing to directional permeability. These results emphasize the importance of impregnation time and fiber orientation in optimizing the flame-retardant treatment processes.

WOOD RESEARCH Volume 70, Number 3, 2025
IRYNA LYTVYN, NATALIYA BEKHTA, IRYNA KUSNIAK, PAVLO BEKHTA, and JÁN SEDLIAČIK

Properties of Particleboards with Partial Replacement of MUF Resin by Sodium and Magnesium Lignosulfonates

The objective of this study was to evaluate the feasibility of partially replacing melamine-urea-formaldehyde (MUF) resin with lignosulfonates and to assess the effects on the physical and mechanical properties of the boards. Particleboards were produced using MUF resin, with partial substitution by either sodium lignosulfonate (NaLS) or magnesium lignosulfonate (MgLS) at levels of 10%, 20%, and 30% by weight. Control boards were also manufactured using 100% MUF resin for comparison. The results demonstrated that both, the type and proportion of lignosulfonate, significantly influenced the physical and mechanical characteristics of the boards. Specifically, the lignosulfonate content had a notable negative effect on the internal bond (IB) strength, bending strength (MOR), and thickness swelling (TS). In contrast, the type of lignosulfonate significantly affected only the IB strength. Boards containing 10% NaLS exhibited comparable properties to those of the control group. Additionally, boards incorporating NaLS generally outperformed those containing MgLS, although the differences were not statistically significant. Particleboards incorporating with 10% or 20% NaLS or MgLS, although exhibiting lower IB strength, MOR and modulus of elasticity (MOE) than the control boards, met the performance criteria for type P2 boards, intended for interior applications (including furniture) in dry conditions, as specified by the EN 312.

WOOD RESEARCH Volume 70, Number 3, 2025
MELİS ÇERÇİOĞLU, MUHAMMED ALİ AYDIN, YASİN KARAŞİN, BURAK BAHAR, and DERYA EŞEN

Effects of mulching on selected properties of soil and young stone pine (Pinus pinea L.) seedlings under semi-arid conditions

Evaporation is a primary source of soil moisture loss, and mulching can effectively reduce this loss, thereby conserving soil moisture. This study examined the effects of wood-materials mulching with various particle sizes and application depths (5-cm thick coarse sawdust, 5-cm thick wood chips, and 10-cm thick wood chips) on some soil properties, including moisture, bulk density (BD), pH, electrical conductivity (EC), organic matter (OM), and CaCO₃, as well as on stone pine (Pinus pinea L.) seedling root collar diameter (RCD), height, sturdiness index (SI), and survival rates. One-year-old containerized stone pine seedlings, a drought-tolerant and economically valuable native conifer species, were planted with a spacing of 3 x 3 m in Aliaga, Izmir, Türkiye. Ten months after treatment (July 2024), no significant differences in soil bulk density and moisture were observed among treatments. The 10-cm-thick wood chips treatment showed significantly greater organic matter content compared to both the control and the 5-cm-thick coarse sawdust treatments. Although large numerical differences were seen in mean pine survival rate and height growth, these differences were not statistically significant, likely due to high data variability. The 10-cm-thick wood chips and 5-cm-thick coarse sawdust treatments demonstrated relatively higher seedling survival rates, while the control treatment showed the lowest seedling survival. However, the control seedlings exhibited significantly greater root RCD than mulch treatments, with the 5-cm-thick coarse sawdust treatment ranking second in promoting seedling RCD. Early results did not indicate enhanced pine survival and growth due to mulching. However, future data collection is recommended to provide further insights.

WOOD RESEARCH Volume 70, Number 3, 2025
ADÉLA VALENTOVÁ, TEREZA MAJSTRÍKOVÁ, and JANA DAŇKOVÁ

MINERALISATION TREATMENT OF WOOD MATRIX BY HYDRATED LIME

This article concerns the application of lime treatment on wood surfaces. This interaction led to alkaline hydrolysis of the polysaccharide component,which isdirectly linked to physical and mechanical parameters.Whereas the composites utilise the advantageous ecological parameters of the lime binder and wood particle filler, it is necessary to describe this utilisation. Thermal analysis indicated that the transformation of hydrate to carbonate occurs relatively quickly in a thin layer, without causing significant changes in the structure of the wood. This is also confirmed by optical microscopy images. Tests onsmall, defect-free specimens were also conducted to assess the impact on compressive strength parallel to the grain.

WOOD RESEARCH Volume 70, Number 3, 2025
DONATA KRUTUL, ANDRZEJ ANTCZAK, MICHAŁ DROŻDŻEK, MONIKA MARCHWICKA, ANDRZEJ RADOMSKI, Teresa Kłosińska, and JANUSZ ZAWADZKI

Influence of urban agglomeration environment pollution on the concentration of some non-metals in the trunk of Acer platanoides L.

The influence of environmental pollution on the concentration of some non-metals in wood and bark from trunks of Acer platanoides L. obtained from the crossroads of Platynowa and Towarowa Streets and KrakowskiePrzedmieście Street in Warsaw was observed. Samples were collected from approx. 30-year-old and 40 year-old trees from the butt-end and the mid-height of the trunk part as well as from the top part. On the cross-section of the butt-end and the mid-height, the following sections were distinguished: outer, middle and pith adjacent middle wood and of the butt-end part bark was obtained. The discs from the upper part of the trunks were not divided into sections due to their small diameter. The concentrations of chlorine (Cl-), nitrate (NO3-), sulphate (SO4-) and hydro phosphate (HPO42-) anions were determined using HPLC with a conductometric detector. The content of nitrogen (N) was examined with the Kjeldahl method. The influence of the environmental pollution caused by urban agglomeration on the nitrogen content was denoted. Additionally, chlorine anions concentrations in wood and bark were increased.

WOOD RESEARCH Volume 70, Number 3, 2025
ERZHUANG ZHAI, SAIYIN FANG, MING LI, TINGTING DENG, BOWEN ZHANG, JIAXIN GUO, KEFEI CHEN, and KUN DU

Research on clustering identification of acoustic emission events in the process of wood crack propagation using PCA

This study presents a methodology for feature extraction and identification of acoustic emission (AE) events during wood crack propagation utilizing Principal component analysis (PCA) and enhanced K-means clustering algorithm. Experimental setups included double cantilever beam (DCB) for mode I crack propagation analysis and three-point bending test for mixed-mode crack propagation assessment. Various AE parameters, such as amplitude, duration, absolute mean value, peak frequency, and frequency centroid, were computed. PCA applied for dimensionality reduction to extract principal components and eliminate redundant information. The optimal number of clusters was determined using a combination of the elbow method and the Davies-Bouldin index to classify damage modes. Results indicate that the principal components contribute to 88.5% and 92% of the variance in the two tests, respectively, yielding three distinct types of AE events in both crack propagation scenarios. Specifically, high-frequency, low-amplitude signals correspond to microcrack initiation; low-frequency, low-amplitude signals signify interface delamination; and high-amplitude, long-duration events indicate mode I opening macroscopic damage (high frequency) and mixed-mode macroscopic failure (low frequency).