Wooden construction material is a sustainable contribution to carbon sequestration and long-term storage. Despite its strength, sustainability and versatility, the vulnerability to biodeterioration is an issue. Therefore, this study aimed to identify the differences in mould growth features and surface extractive composition of the Scots pine (Pinus sylvestris L.) sapwood sideboards between air- and kiln-drying methods using multivariate data analysis. Air and kiln-dried sideboards were used to extract different low molecular compounds from the surface layer, assess the moisture content, and conduct a mould test. Principal component analysis revealed the grouping of the drying types. This was confirmed by partial least-squares discriminant analysis, which allowed the sideboard characteristics of the two wood drying types to be described. An outlier was detected among the air-dried observations. The collected data show more intensive mould growth on kiln-dried Scots pine sideboards than on air-dried ones. Higher amounts of total lipophilic compounds, phenols and inorganic components were found on the kiln-dried sideboard surface. Also, surface extractives from kiln-dried sideboards contained higher amount of almost all analysed fatty and resin acids, except for the oleic acid, which was more prevalent on the air-dried sideboard surface. Low-molecular-weight sugars, namely glucose, saccharose and fructose, were present in significant amounts on the surface of the kiln-dried sideboards. This has presumably contributed to the rapid spread of mould. In general, multivariate modelling allowed to establish that the method of wood drying significantly influenced the redistribution of extractive components on the surface and the subsequent mould growth. 

Resinwood in Scots pine timber resulting from Cronartium pini infection represents an important quality defect, substantially reducing sawn yield and economic value in sawmilling. This dataset generated from X-ray computed tomography (CT) for non-destructive resinwood detection across wood moisture states. Scots pine specimens exhibiting external cankers were harvested and scanned using an industrial MicroTec CT scanner in both green and dry states, included full logs and 3-cm-thick discs. Comparative density analysis identified regions of interest based on elevated density patterns.

The scanner produced data using a cone beam and two angled flat detectors on a helical scanning trajectory. The spatial resolution and resulting voxel dimensions were uniform at 0.3 × 0.3 × 0.3 mm³. The resulting 3D images comprised 16-bit greyscale values representing density in kg/m³ at each location, and helical 1PI Katsevich was used for image reconstruction.

Scots pine (Pinus sylvestris L.) sapwood was modified using maleic anhydride (MA) and sodium hypophosphite (SHP) to improve its durability against wood-deteriorating fungi, mechanical strength, and fire retardancy (thermal stability). The modification significantly reduced mass loss caused by wood-decaying fungi (Trametes versicolor, Rhodonia placenta, and soft rot fungi) due to the formation of cross-links between wood, MA, and SHP, which limited the moisture uptake and altered the chemical structure of wood. On the other hand, the modification did not provide improved resistance to fungi growth on the wood surface, which indicated that the modification had little impact on the accessibility of nutrients on the surface. A bending test showed that the modulus of elasticity (MOE) was not affected by the treatment, whilst the modulus of rupture (MOR) decreased to half the value of untreated wood. Thermal resistance was improved, as demonstrated by micro-scale combustion calorimeter testing, where the total heat release was halved, and the residue percentage nearly doubled. These results indicate that phosphonate protects the modified wood via the formation of a protective char layer on the surface and the formation of radical moieties. Based on the results, wood modified with MA and SHP shows potential for possible use in outdoor, non-loadbearing structures.

Wood is an important construction material, but a significant problem hindering its widespread use is susceptibility to biodeterioration and biodegradation. To protect wood against degradation, a surface coating can be used, and it is important to be able to predict the ability of the coating to prevent fungal growth. The currently available standard method to determine the antifungal efficiency of a coating has two weaknesses, viz. no evaluation of the moisture content in the wood material, and no possibility to study antifungal effect of the coating towards an individual fungus. A new quantitative method of determining the antifungal efficiency of coatings is therefore proposed, where a coating is applied to wood and exposed to an individual fungus in a Petri dish. Six commercial water-based coatings containing synthetic biocides were studied on filter paper (EN 15457) and with the new test method on wood blocks. The results show the importance of studying the antifungal efficiency of a coating using individual fungi instead of a mixture of fungi, since individual fungi interact differently with a given biocide in the coating. The moisture content of the wood substrate during the test was affected by how the fungus was established on the coating. This new test approach shows promise in screening the antifungal efficiency of wood coatings containing preservative substances applied to wood material surfaces.

Resin accumulation (resinwood) in Scots pine timber resulting from Cronartium pini infection represents an important quality defect, substantially reducing sawn yield and economic value in sawmilling. Current timber-grading standards detect resinwood solely through surface characteristics on sawn timber, risking undetected internal deposits until after processing. This study evaluated X-ray computed tomography (CT) for non-destructive resinwood detection across wood moisture states. Scots pine specimens exhibiting external cankers were harvested and scanned using an industrial CT scanner in both green and dry states, included full logs and 3-cm-thick discs. Comparative density analysis identified regions of interest based on elevated density patterns. Validation via acetone extraction quantified resin content in CT-identified resinwood zones versus unaffected wood. CT imaging revealed three characteristic resinwood signatures: (1) growth-ring distortions, (2) non-concentric cambial development, and (3) resin-saturated parenchyma with ground-glass opacity (GGO). Resinwood regions maintained significantly elevated radiographic density in both moisture states. Extraction confirmed substantially higher resin content within CT-identified areas. This moisture-state comparison provides a basis for developing automated CT detection methods in sawmills. These distinct radiographic features offer essential descriptors for detection algorithms, promising enhanced yield and value recovery through minimised resinwood-related defects.

The reaction of wood with maleic anhydride (MA) and sodium hypophosphite (SHP) has been identified as a viable modification method, with macroscopical properties indicating formation of cross-linking to explain the results. However, the chemical reaction between wood and the modification reagents has not been studied yet. To resolve this, the reaction was studied with solid-state 13C cross-polarization magic-angle-spinning (CP-MAS) and 31P MAS nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) to reveal the formation of bonds between wood components, MA and SHP during the treatments to explain the formation of cross-linking and the possible fixation of phosphorus in wood. XPS, solid state 13C and 31P MAS NMR revealed the maleation of wood in the absence of SHP, whilst its presence led to forming a succinic adduct observed through the C-P bond formation, as evidenced by the loss of the maleate C=C bonds at around 130 ppm and the upfield shift of the peak at 165–175 ppm, which was also significantly smoothed, as well as the increase in a peak at 26 ppm due to the reaction between the maleate group and SHP; however, the C-P-C bond could not be unambiguously rationalized from the obtained data. On the other hand, a resonance line at 16 ppm in 31P MAS NMR and the peaks in the XPS P 2p spectrum suggested the formation of a cross-linked structure at low concentrations of SHP, which was more likely to be phosphonate (C-P-O) than organophosphinic acid (C-P-C). The results herein provide a greater fundamental understanding of the mechanisms involved in the reaction of wood, MA and SHP, providing further scope for improved treatment systems in the future.

The rise in energy consumption and the increase in the use of bio-based materials in the building sector, has led to the need to investigate the possibilities to use wood as a porous support material for phase change materials (PCMs), and thereby creating a thermal regulative wood-based product. This study investigated the influence of Kraft lignin-glyoxal prepolymer on the thermal-energy storage properties of wood modified with paraffin-type of PCM. The implementation of the modified wood involves preparing PCM emulsions, synthesising lignin-glyoxal prepolymer, and modifying wood with the PCM-Kraft lignin-glyoxal emulsion through vacuum-pressure impregnation. The infrared imaging suggested the ability of PCM-modified wood to delay the temperature changes, even with the introduction of Kraft lignin-glyoxal prepolymer. In conclusion, it is feasible to introduce thermal-energy storage property into wood with the addition of Kraft lignin-glyoxal prepolymer. Further studies will focus on the long-term thermal storage performance properties when this PCM system is subjected to repeated heating/cooling cycles. 

In this study, Kraft lignin was modified by ammonium dihydrogen phosphate (ADP) and urea for achieving phosphorylation and carbamylation, aiming to protect wood against biological and fire attack. Scots pine (Pinus sylvestris L.) sapwood was impregnated with a water solution containing Kraft lignin, ADP, and urea, followed by heat treatment at 150 °C, resulting in changes in the properties of the Kraft lignin as well as the wood matrix. Infrared spectroscopy, 13C cross-polarisation magic-angle-spinning (MAS) nuclear magnetic resonance (NMR), and direct excitation single-pulse 31P MAS NMR analyses suggested the grafting reaction of phosphate and carbamylate groups onto the hydroxyl groups of Kraft lignin. Scanning electron microscopy with energy dispersive X-ray spectroscopy indicated that the condensed Kraft lignin filled the lumen as well as partially penetrating the wood cell wall. The modified Kraft lignin imparted fire-retardancy and increased char residue to the wood at elevated temperature, as confirmed by limiting oxygen index, microscale combustion calorimetry, and thermogravimetric analysis. The modified wood exhibited superior resistance against mold and decay fungi attack under laboratory conditions. The modified wood had a similar modulus of elasticity to the unmodified wood, while experiencing a reduction in the modulus of rupture.

Poor condition of roofs in terms of decay of shingles and loss of tar-based surface treatments has been revealed in a number of churches at various geographical locations in mid-Sweden. The condition of tars obtained from shingles of selected churches in mid-Sweden were analysed and obtained data were compared with geographical locations of the churches. According to gas chromatography-mass spectroscopy result, dehydroabietic acid was the dominant compound found in the exposed tars from the churches except in church of Malung where similar amounts of retene was found. Oxidised resin acids were found in exposed tars from the churches but not in commercially available pit burned tar. Tar from church shingles had higher char residues than the pit burned tar which was totally consumed when heated under nitrogen gas up to 750°C using thermogravimetric analysis. Scanning electron microscopy with energy dispersive X-ray spectrometer analysis revealed higher amounts of silicates in some exposed tars; however, these compounds constituted only a minor portion of the organic matter in these specimens. Based on the data obtained in the study other factors rather than simply geographical location of churches seemed to be of importance to explain differences of the investigated properties of the church tars.