Special Issue "Surface Properties and Surface Treatments of Wood and Wood-Based Composites"

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Characterization, Deposition and Modification".

Deadline for manuscript submissions: closed (30 November 2021).

Special Issue Editor

Prof. Dr. Marko Petric
E-Mail Website
Guest Editor
Department of Wood Science & Technology, Biotechnical faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
Interests: wood coatings for interior and exterior; interactions of wood coatings with various substrates (wood, modified wood, densified wood); wood liquefaction and preparation of new wood coatings on the basis of liquefied wood; applications of nanomaterials in wood coatings and in treatment of wood; surface properties of wood and lignocellulosic materials

Special Issue Information

Dear Colleagues,

Whenever products made of wood or wood-based composites are utilized, when their weathering is studied, or when the processes of wood deterioration due to exposure to biotic or abiotic factors are investigated, it is the surface of the object under consideration that must be taken into account at first. Therefore, surface properties of wood have to be known well and tailored to the purpose. Proper surface characterization and treatment methods must be selected to get the most relevant surface properties. Some surface treatment process are well established, like surface finishing of wood with coatings, and others are less known, and their potentials are underestimated. Just to illustrate, this is also the case with plasma treatments, which have been utilized for decades, but the potentials of this technique for treatment of wood and wood-based composites would deserve larger attention, both from a research as well as from an industrial exploitation point of view.

This Special Issue will serve as a forum for papers in the following concepts:

  • Surface finishing of wood and wood-based composites with all kinds of stains and film-forming coatings to obtain a fit-for-purpose finished product;
  • Properties of wood surface systems, including resistance to weathering and biological deterioration parameters;
  • Plasma treatments;
  • Functionalization of lignocellulosic material surfaces, e.g., by grafting, sol–gel treatments, deposition of nanoparticles;
  • Surface-free energy of lignocellulosic materials, either untreated or finished;
  • Wettability of wood and wood-based materials and their treated surfaces;
  • Microscopic and spectroscopic surface analytical methods;
  • Adsorption phenomena on untreated and surface finished lignocellulosic materials.

Prof. Dr. Marko Petric
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Protective and decorative wood finishes
  • Surface properties of wood and wood-based materials
  • Plasma treatments
  • Functionalization, grafting, sol–gel, nanoparticles

Published Papers (6 papers)

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Research

Article
Quality of Oil- and Wax-Based Surface Finishes on Thermally Modified Oak Wood
Coatings 2021, 11(2), 143; https://doi.org/10.3390/coatings11020143 - 28 Jan 2021
Cited by 3 | Viewed by 624
Abstract
In this study, natural linseed oil, hard wax oil, and hard wax, commonly used as finishes for wooden furniture and parquet, were used for surface finishes on Turkey oak wood (Quercus cerris L.), thermally modified at temperatures of 175 °C and 195 [...] Read more.
In this study, natural linseed oil, hard wax oil, and hard wax, commonly used as finishes for wooden furniture and parquet, were used for surface finishes on Turkey oak wood (Quercus cerris L.), thermally modified at temperatures of 175 °C and 195 °C for 4 h. Several resistance surface properties were investigated. The mechanical resistance properties of all surface finishes were very much allied to interactions between the finish and the type of substrate. The adhesion strength and impact resistance decreased if higher temperature was used for thermal modification of the substrate. The surface hardness and the resistance to abrasion were high and increased slightly with increasing temperature during thermal modification of wood. It was also found that surface adhesion, hardness and resistance to impact were very much related to interactions between the coating film and the substrate. The resistance properties of finishes, such as resistance to cold liquids and mold, were mainly influenced by the type of the surface finish. The resistance to cold liquids increased in the order: surface finish with hard wax < linseed oil < finish system of linseed oil + hard wax oil. The lowest resistance to cold liquids showed up in condensed milk and sanitizer. Resistance to Aspergillus niger and Penicillium purpurogenum was relatively weak, however apparently improved during the first 7 days of the fungal test; the surfaces were covered with a lower distribution density of fungal mycelium after 21 days of the fungal test. Individual surface performances of oil and wax-based surface finishes on native wood were different from thermally modified wood. Full article
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Article
Superhydrophilic Coating of Pine Wood by Plasma Functionalization of Self-Assembled Polystyrene Spheres
Coatings 2021, 11(2), 114; https://doi.org/10.3390/coatings11020114 - 20 Jan 2021
Cited by 1 | Viewed by 856
Abstract
Self-assembling films typically used for colloidal lithography have been applied to pine wood substrates to change the surface wettability. Therefore, monodisperse polystyrene (PS) spheres have been deposited onto a rough pine wood substrate via dip coating. The resulting PS sphere film resembled a [...] Read more.
Self-assembling films typically used for colloidal lithography have been applied to pine wood substrates to change the surface wettability. Therefore, monodisperse polystyrene (PS) spheres have been deposited onto a rough pine wood substrate via dip coating. The resulting PS sphere film resembled a polycrystalline face centered cubic (FCC)-like structure with typical domain sizes of 5–15 single spheres. This self-assembled coating was further functionalized via an O2 plasma. This plasma treatment strongly influenced the particle sizes in the outermost layer, and hydroxyl as well as carbonyl groups were introduced to the PS spheres’ surfaces, thus generating a superhydrophilic behavior. Full article
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Article
Interactions of Coating and Wood Flooring Surface System Properties
Coatings 2021, 11(1), 91; https://doi.org/10.3390/coatings11010091 - 15 Jan 2021
Cited by 5 | Viewed by 686
Abstract
Parquet flooring is one of the most common types of flooring, the surface of which can be covered with various coatings. To avoid possible damage to the parquet during use, it is necessary to test the surfaces before installation according to various non-standard [...] Read more.
Parquet flooring is one of the most common types of flooring, the surface of which can be covered with various coatings. To avoid possible damage to the parquet during use, it is necessary to test the surfaces before installation according to various non-standard and standard protocols. The present study provides an overview of the interactions between the properties of selected waterborne coatings (solids content, hardness, resistance to cracking, tensile strength) and the properties of oak wood flooring surfaces (dry film thickness, coating adhesion, resistance to scratching, impact, abrasion and cold liquids). The tests conducted showed that the performance of the surface systems was highly dependent on the coating formulations, as they were either one- or two-component systems. Although no major differences in surface resistance to cold liquids were found, there was a correlation between coating thickness, hardness and tensile strength. The harder coatings had higher tensile strengths and lower elongations. The coatings with higher tensile strength and better hardness achieved better adhesion properties. The coatings that exhibited ductile behavior showed the worst scratch resistance. A statistically significant relationship was found between the higher resistance of the flooring systems to impact stress and the improved abrasion resistance. The obtained results provide potential end users of surface coatings with valuable information on the quality that can be expected in wood flooring. Full article
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Article
Enhancing Thermally Modified Wood Stability against Discoloration
Coatings 2021, 11(1), 81; https://doi.org/10.3390/coatings11010081 - 13 Jan 2021
Cited by 3 | Viewed by 785
Abstract
Thermal modification of wood has gained its niche in the production of materials that are mainly used for outdoor applications, where the stability of aesthetic appearances is very important. In the present research, spectral sensitivity to discoloration of thermally modified (TM) aspen wood [...] Read more.
Thermal modification of wood has gained its niche in the production of materials that are mainly used for outdoor applications, where the stability of aesthetic appearances is very important. In the present research, spectral sensitivity to discoloration of thermally modified (TM) aspen wood was assessed and, based on these results, the possibility to delay discoloration due to weathering by non-film forming coating containing transparent iron oxides in the formulation was studied. The effect of including organic light stabilizers (UVA and HALS) in coatings as well as pretreatment with lignin stabilizer (HALS) was evaluated. Artificial and outdoor weathering was used for testing the efficiency of different coating formulations on TM wood discoloration. For color measurements and discoloration assessment, the CIELAB color model was used. Significant differences between the spectral sensitivity of unmodified and TM wood was observed by implying that different strategies could be effective for their photostabilization. From the studied concepts, the inclusion of the transparent red iron oxide into the base formulation of the non-film forming coating was found to be the most effective approach for enhancing TM wood photostability against discoloration due to weathering. Full article
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Article
Study of the Adhesion of Silicate-Based Coating Formulations on a Wood Substrate
Coatings 2021, 11(1), 61; https://doi.org/10.3390/coatings11010061 - 07 Jan 2021
Cited by 4 | Viewed by 813
Abstract
Silicate coatings are environmentally friendly inorganic-based products that have long been used for mineral substrates and protection of steel against corrosion. The development and acceptance of these coatings in the wood sector require some adjustments in formulations or special preparation of the surface [...] Read more.
Silicate coatings are environmentally friendly inorganic-based products that have long been used for mineral substrates and protection of steel against corrosion. The development and acceptance of these coatings in the wood sector require some adjustments in formulations or special preparation of the surface to be coated to obtain durable finishes. In this work, the adhesion of various silicate-based formulations to a beech wood substrate (Fagus sylvatica L.), was assessed with the main objective to study relevant parameters and potential improvements. Adhesion strength was determined by pull-off and cross-cut tests. Other coating properties such as scratch, impact, and water resistance were also determined. Surface roughness and interface were analyzed using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), and coating curing was studied by attenuated total reflection-infrared spectroscopy (ATR FTIR). The results showed that adhesion was highly dependent on formulation, penetration of the coatings into wood, and mechanical anchoring. Increasing the content of solid particles in the coating formulations or adding a polyol (glycerol, xylose), which probably acted as a coalescent, considerably decreased the adhesion strength, probably by blocking penetration into the wood by forming aggregates. Adhesion was improved by pre-mineralization of the surface, and substitution of a part of the potassium silicate binder with potassium methyl siliconate reduced the formation of cracks caused by dimensional instability of the wood. Full article
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Article
Fire Characteristics of Selected Tropical Woods without and with Fire Retardant
Coatings 2020, 10(6), 527; https://doi.org/10.3390/coatings10060527 - 29 May 2020
Cited by 6 | Viewed by 1092
Abstract
The flammability of tropical woods and the effect of a selected fire protection coating were evaluated using a cone calorimeter at a cone radiancy of 35 kW/m2. Three samples were from the South American continent (Cumaru, Garapa, Ipe), and two were [...] Read more.
The flammability of tropical woods and the effect of a selected fire protection coating were evaluated using a cone calorimeter at a cone radiancy of 35 kW/m2. Three samples were from the South American continent (Cumaru, Garapa, Ipe), and two were from the Asian continent (Kempas and Merbau). Samples were treated with commercial fire retardant (FR) containing ferrous phosphate as an essential component. The untreated samples were used as reference materials that were of particular interest concerning their flammability. It was shown that there is unambiguous correlation between the effective heat of combustion (EHC) and total oxygen consumed (TOC) related to mass lost during burning for both the untreated and treated samples. In the case of Cumaru and Garapa, there exists an inverse relation between the amount of smoke and carbon residue. The decisive effect on the time of ignition was performed by the initial mass of the sample. This is valid for the spruce and the Cumaru, Ipe, and Kempas, both treated and untreated with retardant, while Garapa and Merbau were found to decline. According to the lower maximum average rate of heat emission (MARHE) parameter, a lower flammability was observed for the treated samples of wood, except for Garapa wood. Fire-retardant treated Garapa and Merbau also have a significantly lower time to ignition than untreated ones. Full article
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