Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Wood composites have gained significant interest over years and remain one of the most material in the construction and furniture industries. Given the unsustainability of synthetic binder systems used for the production of wood-based composites, coupled to the related health and environmental issues, there is a great need for alternative safer solution. The present study finds its originality in developing eco-friendly particleboards for exterior purpose. Most of the wood-based composites used for façade building contain expensive petroleum-based adhesives or plastic components. The study stands out at it assesses a more or less binderless system.

The methodology is very well described. The only consideration would have been using the same particle size for both production processes.

NB. Table 3 should be checked. Some of the RIB values are not consistent.

The conclusions drawn are consistent with the result presented and reflect the main question addressed.

Aside from the following minor comments, I do believe this is a good scientific piece of work and recommend it for publication.


Line 128-131: these two sentences are more of a conclusion of the present study. This doesn’t fit here. Rather the objective of the experiment is expected at this point.

Line 154-157: why using different MC content and processing at different temperatures? An explanation is necessary for better understanding.

Line 174: the mechanical properties of particleboards (especially the IB) is highly influenced by the particle size. The use of different particle size for the two main treatment (SE and SA) introduces a bias. The two variants cannot be directly compared without looking into the influence of the “particle size” parameter.

Line 562: provide the ISBN.

Line 567: conference paper. Should be specified

Line 569: this reference has an ISNB. Please do provide it.

Line 573: provide the DOI

Line 589: provide the DOI

Line 604: provide the DOI

Line 616: provide the DOI

Line 618: provide the DOI

Line 625: provide the DOI

Line 647: provide the DOI

Author Response

Comments 1: Wood composites have gained significant interest over years and remain one of the most material in the construction and furniture industries. Given the unsustainability of synthetic binder systems used for the production of wood-based composites, coupled to the related health and environmental issues, there is a great need for alternative safer solution. The present study finds its originality in developing eco-friendly particleboards for exterior purpose. Most of the wood-based composites used for façade building contain expensive petroleum-based adhesives or plastic components. The study stands out at it assesses a more or less binderless system.

Response 1: Thank you for your evaluation!

Comments 2: The methodology is very well described.

Response 2: Thank you.

Comments 3: The only consideration would have been using the same particle size for both production processes.

Response 3: Thank you for suggesting. However, it was checked before and concluded the particle size should be higher for SE processing because the process reduces the size more severe; In turn, the particle size in case of SA binder should be smaller than for SE process because it is similar to standard particleboard production.

Comments 4:  Table 3 should be checked. Some of the RIB values are not consistent.

Response 4: We have checked the RIB values in Table 3. Despite the huge difference, they are consistent and discussed in the text (lines 290-299) demonstrating the impact of both the biomass species and the manufacturing technology used.

Comments 5: The conclusions drawn are consistent with the result presented and reflect the main question addressed.

Response 5: Thank you very much for excellent evaluation!

Comments 6: Aside from the following minor comments, I do believe this is a good scientific piece of work and recommend it for publication.

Response 6: Thank you very much for the high evaluation!

Comments 7: Line 128-131: these two sentences are more of a conclusion of the present study. This doesn’t fit here. Rather the objective of the experiment is expected at this point.

Response 7: These two sentences here were added due to a recommendation in the journal template advising the following for the Introduction: “…briefly mention the main aim of the work and highlight the principal conclusions”.

Comments 8: Line 154-157: why using different MC content and processing at different temperatures? An explanation is necessary for better understanding.

Response 8: Thank you for suggestion. The explanation about different MC and temperature in SE process was added in lines 151-156.

Comments 9: Line 174: the mechanical properties of particleboards (especially the IB) is highly influenced by the particle size. The use of different particle size for the two main treatment (SE and SA) introduces a bias. The two variants cannot be directly compared without looking into the influence of the “particle size” parameter.

Response 9: Different particle sizes were selected based on our previous experience, literature, board production approach, and the technology used. The influence of SE particle size on resulting board properties was explored before concluding to an optimal 10 mm sieve size. The SE process doesn’t require small-dimension chips because the process itself easily reduces the size close to fiber dimensions. Figure 3 clearly demonstrates that even though the initial particle dimension was higher for the SE process, it is substantially lower in the final board compared to the particles in the SA board. Besides, the IB of the boards is highly impacted not only by the particle size but also by the binder used and species as well. Our previous study (https://doi.org/10.3390/f16081359) showed that the same IB of the boards can be achieved in spite of different board production technologies.

Comments 10: Line 562: provide the ISBN.

Response 10: The journal doesn't require an ISBN, but it was added by your request. ISBN 978-1-8594-6184-6.

Comments 11: Line 567: conference paper. Should be specified

Response 11: It is specified that the conference of IBPC.

Comments 12: Line 569: this reference has an ISNB. Please do provide it.

Response 12: The ISBN 2035 798 was provided.

Comments 13: Line 573: provide the DOI

Response 13: The DOI is provided.

Comments 14: Line 589: provide the DOI

Response 14: The DOI is provided.

Comments 15: Line 604: provide the DOI

Response 15:  The DOI https://doi.org/10.1007/BF00223474 is provided

Comments 16: Line 616: provide the DOI

Response 16: The DOI https://doi.org/10.1007/s11029-021-09933-6 has been included.

Comments 17: Line 618: provide the DOI

Response 17: The DOI https://doi.org/ 10.3390/f16081359 has been provided.

Comments 18: Line 625: provide the DOI

Response 18: This specific journal volume from the Slovak Forest Products Research Institute does not assign Digital Object Identifiers (DOIs) to its older papers.

Comments 19: Line 647: provide the DOI.

Response 19: The DOI https://doi.org/10.3390/ polym14112304 has been provided.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear, the manuscript addresses a highly relevant and innovative topic in the field of fully bio-based panels for exterior applications; however, a major revision is required to resolve several methodological contradictions, particularly regarding the technological justification of the coatings and the consistency of the sample nomenclature.

• Lines 24–26: It is stated that only two variants (GASA and SWSA) met the EN 312 water resistance requirement (0.09 N/mm²). The authors should explicitly indicate in the abstract that this requirement refers to P3-class boards (non-load-bearing boards for use in humid conditions), which is only mentioned later in the conclusion. Without specifying the exact class (e.g., P3 or P5), the value of 0.09 N/mm² lacks sufficient context for the average reader.
• Line 27: The statement containing the “less than or equal to” symbol does not clearly explain whether the coating actually improved hydrophobicity. The sentence should be reformulated to clearly state that the coatings did not significantly increase the static contact angle compared to the reference board (REFO).
• Lines 42–80: This section of the introduction focuses excessively on the general commercial classification of façade materials (e.g., Alucobond laminates, glass, ceramics, geopolymers).
• The introduction is overly broad in terms of construction applications and places insufficient emphasis on biomass chemistry and the self-bonding mechanisms occurring during steam explosion (SE) treatment and the polymerization of suberinic acids (SA).
• The paragraphs discussing metal and cement-based façades should be shortened, while additional literature should be incorporated to explain the roles of lignin and hemicelluloses during SE treatment, as well as the function of SA as a bio-based binder.
• Lines 112–114: The authors cite their previous study [23], where self-bonded grey alder (GA) boards subjected to SE treatment retained 43–49% of their IB strength after boiling, whereas in the present study (Table 3), GASE exhibits a retention of only 0.9%. This discrepancy is substantial. Although the authors attempt to explain it in Section 3.1.2 through differences in initial moisture content (MC), this explanation should be highlighted more clearly here or discussed in greater detail later.
• Line 136: The softwood (SW) composition is reported as 50/50 wt.%. A standard mass-fraction format should be used instead of LaTeX-style notation for simple percentages in the text (e.g., 50% fir / 50% pine).
• The SW treatment was carried out at 230 °C for 90 s, whereas WS and GA were treated at 220 °C for 120 s. The authors should justify the use of more severe temperature conditions for softwoods. It is well known that softwoods generally require higher activation energy due to their lignin structure (guaiacyl-dominated versus syringyl-rich hardwood lignin), but this should be supported with a scientific explanation or appropriate reference.
• The schematic diagram (Figure 1) is graphically very basic. The labels at the bottom of the figure (“Mold: SE-M, SA-M” and “Conventional: SE-C, SA-C”) are not fully consistent with the nomenclature used in Table 4, where the designations “−SF” and “+SF” (without and with soluble fraction, respectively) are introduced.
• Figure 1 should be revised to clearly illustrate the branching of the process into sub-variants with and without the soluble fraction (SF), as the current presentation creates confusion in the subsequent sections of the manuscript.
• Line 182: The SA binder content is reported as 16–18%. Why is a range provided? Were some boards manufactured with 16% and others with 18% binder content? Scientific reporting requires precise values. If the percentage depended on biomass type (e.g., due to differences in the specific surface area of wheat straw particles compared with wood particles), this should be explicitly stated in Table 1.
• Lines 258–262 (Figure 2): In Figure 2, the standard deviation (error bar) for GA under the “SA” category (GASA board) is exceptionally high (IBboil_{boil}boil​ = 0.81 ± 0.23 N/mm²). This indicates considerable heterogeneity within the laboratory-manufactured boards or possible issues related to SA binder application. The authors should comment on this variability in the text and provide a brief explanation as to why conventionally pressed SA boards exhibit much greater variability than mold-pressed SA-M boards.
• Lines 273–277 (Table 3): The initial IB value (before boiling) of GASE reaches 3.04 N/mm², but after boiling it decreases to only 0.03 N/mm² (a reduction of 99.1%). In contrast, the authors’ previous studies reported exceptionally high water resistance for SE boards. The explanation provided in Lines 387–393 (effects of initial moisture content and pseudo-lignin formation) is reasonable, but lacks direct chemical evidence. If pseudo-lignin formation was indeed responsible for the improved performance in earlier studies, does the FTIR spectrum in the present work confirm its presence? The authors should explicitly connect the FTIR analysis with this claim.
• Lines 355–357: The authors report correlation coefficients (r = 0.69 for WS and r = −0.80 for GA). The corresponding p-values should also be provided to demonstrate the statistical significance of these correlations, particularly since Section 2.6 states that ANOVA was conducted at a significance level of α = 0.05.
• Figures 8 and 9 (Contact Angle): The results appear to contradict the primary objective of the study. Coatings based on suberinic acids and chitosan were developed to improve water resistance; however, Figure 9 clearly shows that the uncoated board (SA REFO) exhibits a higher contact angle (above 90°) throughout the measurement period than boards coated with pure suberinic acid (SA S) or pigmented formulations (SA SP). Why would one apply a coating that reduces the initial contact angle and increases surface wetting?
• In Lines 442–443, the authors state that the “surface is already dominated by the chemistry of SA originating from the board itself.” If this is the case, then the additional coating appears technologically unnecessary for hydrophobicity enhancement. This is further supported by the observation that even the commercial reference coating (REF1) exhibits a lower contact angle than SA REFO. The authors should critically discuss the economic and technological justification for coating SA-bonded boards under these circumstances.

Author Response

Comment 1. Lines 24–26: It is stated that only two variants (GASA and SWSA) met the EN 312 water resistance requirement (0.09 N/mm²). The authors should explicitly indicate in the abstract that this requirement refers to P3-class boards (non-load-bearing boards for use in humid conditions), which is only mentioned later in the conclusion. Without specifying the exact class (e.g., P3 or P5), the value of 0.09 N/mm² lacks sufficient context for the average reader.

Response 1: Thank you for the suggestion. The requirement for board Type P3 was indicated in the abstract and the section 2.6 (lines 235-236).

Comment 2. Line 27: The statement containing the “less than or equal to” symbol does not clearly explain whether the coating actually improved hydrophobicity. The sentence should be reformulated to clearly state that the coatings did not significantly increase the static contact angle compared to the reference board (REFO).

Response 2. The sentence was reformulated according to your suggestion.

Comment 3. Lines 42–80: This section of the introduction focuses excessively on the general commercial classification of façade materials (e.g., Alucobond laminates, glass, ceramics, geopolymers).

Response 3. The indicated lines indeed include general commercial classification of current façade materials. For our understanding, the information should be retained since our investigated boards are intended for application in façade. But yes, we agree the section was excessively focused, therefore, it was shortened (lines 42-61).

Comment 4. The introduction is overly broad in terms of construction applications and places insufficient emphasis on biomass chemistry and the self-bonding mechanisms occurring during steam explosion (SE) treatment and the polymerization of suberinic acids (SA).

Response 4. Thank you for suggestion. The part for construction applications was shortened. Instead, the emphasis highlighted on biomass chemistry and the self-bonding impacted by SE treatment and SA as binder.

Comment 5. The paragraphs discussing metal and cement-based façades should be shortened, while additional literature should be incorporated to explain the roles of lignin and hemicelluloses during SE treatment, as well as the function of SA as a bio-based binder.

Response 5: The paragraphs discussing metal and cement-based façades were shortened. The roles of lignin and hemicelluloses during SE treatment and using SA as a bio-based binder were explained introducing an additional literature.

Comment 6. Lines 112–114: The authors cite their previous study [23], where self-bonded grey alder (GA) boards subjected to SE treatment retained 43–49% of their IB strength after boiling, whereas in the present study (Table 3), GASE exhibits a retention of only 0.9%. This discrepancy is substantial. Although the authors attempt to explain it in Section 3.1.2 through differences in initial moisture content (MC), this explanation should be highlighted more clearly here or discussed in greater detail later.

Response 6: The discrepancy of the board’s moisture resistance during the present and previous studies was explained additionally in details in lines 385-399.

Comment 7. Line 136: The softwood (SW) composition is reported as 50/50 wt.%. A standard mass-fraction format should be used instead of LaTeX-style notation for simple percentages in the text (e.g., 50% fir / 50% pine).

Response 7: The formulation of the sentence was changed.

Comment 8: The SW treatment was carried out at 230 °C for 90 s, whereas WS and GA were treated at 220 °C for 120 s. The authors should justify the use of more severe temperature conditions for softwoods. It is well known that softwoods generally require higher activation energy due to their lignin structure (guaiacyl-dominated versus syringyl-rich hardwood lignin), but this should be supported with a scientific explanation or appropriate reference.

Response 8: The explanation about the different choice in SE pretreatment between the used species was expanded in the section 2.2.

Comment 9: The schematic diagram (Figure 1) is graphically very basic. The labels at the bottom of the figure (“Mold: SE-M, SA-M” and “Conventional: SE-C, SA-C”) are not fully consistent with the nomenclature used in Table 4, where the designations “−SF” and “+SF” (without and with soluble fraction, respectively) are introduced.

Response 9: Thank you for the suggestion. The labels in Figure 1 were aligned with the nomenclature in the Tables 1, 3 and 4.

Comment 10: Figure 1 should be revised to clearly illustrate the branching of the process into sub-variants with and without the soluble fraction (SF), as the current presentation creates confusion in the subsequent sections of the manuscript.

Response 10: Figure 1 was revised and highlighted by colors preventing the confusion of used processing and labeling.

Comment 11. Line 182: The SA binder content is reported as 16–18%. Why is a range provided? Were some boards manufactured with 16% and others with 18% binder content? Scientific reporting requires precise values. If the percentage depended on biomass type (e.g., due to differences in the specific surface area of wheat straw particles compared with wood particles), this should be explicitly stated in Table 1.

Response 11: The SA binder content indicated in range of 16-18% is related to slight differences in MC of used biomass species and solid content of SA binder between several synthesis. If it is more appropriate, the SA range can be also averaged and presented as 17±1%.

Comment 12. Lines 258–262 (Figure 2): In Figure 2, the standard deviation (error bar) for GA under the “SA” category (GASA board) is exceptionally high (IBboil_{boil}boil​ = 0.81 ± 0.23 N/mm²). This indicates considerable heterogeneity within the laboratory-manufactured boards or possible issues related to SA binder application. The authors should comment on this variability in the text and provide a brief explanation as to why conventionally pressed SA boards exhibit much greater variability than mold-pressed SA-M boards.

Response 12: Yes, we agree that the obtained IBboil deviation of GASA boards is exceptionally high. The explanation of such aspect was added in lines 268-278.

Comment 13. Lines 273–277 (Table 3): The initial IB value (before boiling) of GASE reaches 3.04 N/mm², but after boiling it decreases to only 0.03 N/mm² (a reduction of 99.1%). In contrast, the authors’ previous studies reported exceptionally high water resistance for SE boards. The explanation provided in Lines 387–393 (effects of initial moisture content and pseudo-lignin formation) is reasonable, but lacks direct chemical evidence. If pseudo-lignin formation was indeed responsible for the improved performance in earlier studies, does the FTIR spectrum in the present work confirm its presence? The authors should explicitly connect the FTIR analysis with this claim.

Comment 14. Lines 355–357: The authors report correlation coefficients (r = 0.69 for WS and r = −0.80 for GA). The corresponding p-values should also be provided to demonstrate the statistical significance of these correlations, particularly since Section 2.6 states that ANOVA was conducted at a significance level of α = 0.05.

Response 14: You are right, the statistical significance was not approved by ANOVA of the detected correlation that was additionally noted in lines 376-379.

Comment 15. Figures 8 and 9 (Contact Angle): The results appear to contradict the primary objective of the study. Coatings based on suberinic acids and chitosan were developed to improve water resistance; however, Figure 9 clearly shows that the uncoated board (SA REFO) exhibits a higher contact angle (above 90°) throughout the measurement period than boards coated with pure suberinic acid (SA S) or pigmented formulations (SA SP). Why would one apply a coating that reduces the initial contact angle and increases surface wetting?

Response 15: Yes, Figure 9 shows that the applied coatings did not increase the initial water contact angle. However, contact angle reflects primarily the surface free energy and micro‑roughness of the outermost surface layer, rather than the bulk water resistance of the board. In our case, the coatings slightly smoothened or chemically altered the surface, reducing the apparent hydrophobicity, while still providing a clear improvement in water resistance under boiling conditions (Figures 5–7). Thus, although the coatings do not enhance surface wettability, they significantly contribute to moisture protection at the structural level, which was the main objective of the study.

Comment 16. In Lines 442–443, the authors state that the “surface is already dominated by the chemistry of SA originating from the board itself.” If this is the case, then the additional coating appears technologically unnecessary for hydrophobicity enhancement. This is further supported by the observation that even the commercial reference coating (REF1) exhibits a lower contact angle than SA REFO. The authors should critically discuss the economic and technological justification for coating SA-bonded boards under these circumstances.

Response 16: As noted in Response 15, the development and application of SA‑based coatings was a secondary objective of this study, intended to evaluate newly formulated bio‑based finishing systems rather than to enhance surface hydrophobicity alone. Although the contact angle results indicate that the coatings do not increase the initial surface hydrophobicity, this parameter reflects primarily surface free energy and micro‑roughness, not the bulk water resistance of the board. The technological rationale for applying SA‑based coatings lies in their ability to reduce moisture ingress into the particleboard structure during boiling, as demonstrated by the improved IBboil values (Figures 5–7). Therefore, even if the surface chemistry of SA‑bonded boards already provides high intrinsic hydrophobicity, the coatings remain relevant as protective systems aimed at improving structural moisture resistance rather than modifying surface wettability.

Reviewer 3 Report

Comments and Suggestions for Authors

Review of the manuscript ID – thermo-4338389

 

Water resistance of fully bio-based particleboard intended for building façade application

 

The article addresses an important topic related to the development and evaluation of the properties of boards made from alternative raw materials, intended for sustainable construction, which the Authors refer to as facade boards. The research was conducted properly, although it requires further elaboration, and the results are presented in a relatively clear manner. Nevertheless, the manuscript requires further elaboration and clarification of several important issues.

Specific comments:

 

1. The very high density of the manufactured boards, in the range of 1200 kg/m³, is noteworthy. The Authors should explain why such a high level of material compaction was chosen and what technological or practical considerations motivated this decision. This issue should be addressed in the section on materials and test methods and referenced in the discussion of the results.
2. The greatest concern arises from the Authors’ choice of P3 boards as the reference material. In the article, the boards under study are referred to as “facade boards,” but it is not specified exactly what construction application is intended for these products or what performance requirements they should meet. The Authors should explain why P3 boards were chosen as the reference point, as these are intended, according to the standard, for non-structural applications in humid conditions, that is, in interior environments, such as in the production of furniture for rooms with elevated humidity. Furthermore, facade applications involve not only the effects of moisture but also the need to ensure appropriate mechanical properties and service life. Therefore, the adopted classification should be justified, and it should be explained why a reference to the requirements for boards intended specifically for construction applications, i.e. P5 boards for which IB_boil is 0.15 N/mm² was not considered. This is particularly important in the context of frame construction, where panels installed on the exterior side of the partition also serve a structural function and stiffen the structure.
3. The Authors evaluated the internal bond (IB) of the boards, but did not present the results of basic mechanical tests, such as the modulus of bending (MOR) and the modulus of elasticity in bending (MOE). In my opinion, these parameters are essential for assessing the suitability of the panels for construction applications, especially if the Authors suggest the possibility of using them as facade boards. The absence of these tests prevents a full assessment of the performance characteristics of the manufactured boards and limits the practical value of the presented results. I suggest supplementing the research..
4. The Authors report that an analysis of variance (ANOVA) was performed, but the results of this analysis are not presented in the manuscript. The tables and figures show only the mean values and standard deviations. The article should be supplemented with the results of the statistical analysis, including information regarding the significance of differences between the study groups (p-values, homogeneous groups, results of post hoc tests, or other statistical indicators used). Currently, it is not possible to verify which differences between the results are statistically significant.
5. The reference to the literature [25] in lines 265–268 appears irrelevant to the topic of the article. The cited paper shows no direct connection to the research issues presented in the paper and does not provide an adequate justification for the research undertaken. This section should be revised and supplemented with more appropriate literature sources.
6. Figure 2 should be removed. It presents data that is also included in Table 3, resulting in unnecessary duplication of results. Furthermore, the graph is difficult to read and does not provide any additional information that would facilitate the interpretation of the results.
7. Figure 8 is also difficult to read; it should be divided into four separate figures: SE, SE-M, SA, and SA-M.
8. Please standardize the terminology: “boards” or “panels”
9. In their conclusions, the Authors state that the tested GASA and SWSA boards meet the P3 class requirements for IB_boil and TS-boil and can be used in finishing systems; however, in light of the comments presented, this conclusion seems overly broad. The tests conducted do not cover all the properties required for a full assessment of compliance with the requirements of this board class. In particular, the results for bending strength (MOR) and bending modulus of elasticity (MOE) were not presented. Therefore, based on the presented results, it can only be concluded that the tested panels meet the requirements of type P3 with regard to the analyzed properties; however, there is no basis for concluding full compliance with the requirements of this type.

 

Recommendations – major revision

Comments for author File: Comments.pdf

Author Response

Comment 1: The very high density of the manufactured boards, in the range of 1200 kg/m³, is noteworthy. The Authors should explain why such a high level of material compaction was chosen and what technological or practical considerations motivated this decision. This issue should be addressed in the section on materials and test methods and referenced in the discussion of the results.

Response 1: The density of boards was chosen by analogy to commercial cement-based particleboards typically used in ventilated façade systems. As well, due to the fact that properties of particleboards are density-dependent. The clarification was added in lines 186-189.

Comment 2: The greatest concern arises from the Authors’ choice of P3 boards as the reference material. In the article, the boards under study are referred to as “facade boards,” but it is not specified exactly what construction application is intended for these products or what performance requirements they should meet. The Authors should explain why P3 boards were chosen as the reference point, as these are intended, according to the standard, for non-structural applications in humid conditions, that is, in interior environments, such as in the production of furniture for rooms with elevated humidity. Furthermore, facade applications involve not only the effects of moisture but also the need to ensure appropriate mechanical properties and service life. Therefore, the adopted classification should be justified, and it should be explained why a reference to the requirements for boards intended specifically for construction applications, i.e. P5 boards for which IB_boil is 0.15 N/mm² was not considered. This is particularly important in the context of frame construction, where panels installed on the exterior side of the partition also serve a structural function and stiffen the structure.

Response 2: Thank you for the discussion. Requirements of P3 boards as the reference material were chosen because they are intended for use in humid environments. We agree that P5 boards could be more appropriate for our case, as we are developing the boards for external facades. But actually, we don’t think the choice of the reference matters greatly since both P3 and P5 require the testing of water resistance by one of the options. We chose the option of boiling treatment and obtained the results, two cases of which meet both the requirements of P3 and P5. This was highlighted in the revised version of the manuscript (e.g., line 277). Regarding the mechanical properties, they also meet the P5 and were presented in our previous study [33].

Comment 3: The Authors evaluated the internal bond (IB) of the boards, but did not present the results of basic mechanical tests, such as the modulus of bending (MOR) and the modulus of elasticity in bending (MOE). In my opinion, these parameters are essential for assessing the suitability of the panels for construction applications, especially if the Authors suggest the possibility of using them as facade boards. The absence of these tests prevents a full assessment of the performance characteristics of the manufactured boards and limits the practical value of the presented results. I suggest supplementing the research.

Response 3: We agree that assessment of the performance characteristics of the manufactured boards is essential. Actually, they were studied and presented in our previous study [33]. This message was highlighted in the last paragraph of the introduction.

Comment 4: The Authors report that an analysis of variance (ANOVA) was performed, but the results of this analysis are not presented in the manuscript. The tables and figures show only the mean values and standard deviations. The article should be supplemented with the results of the statistical analysis, including information regarding the significance of differences between the study groups (p-values, homogeneous groups, results of post hoc tests, or other statistical indicators used). Currently, it is not possible to verify which differences between the results are statistically significant.

Response 4: Thank you for this important comment. Statistical evaluation in terms of significance between the board groups was introduced in Tables 3 and 4.

Comment 5: The reference to the literature [25] in lines 265–268 appears irrelevant to the topic of the article. The cited paper shows no direct connection to the research issues presented in the paper and does not provide an adequate justification for the research undertaken. This section should be revised and supplemented with more appropriate literature sources.

Response 5: We don’t agree that the literature [25] cited doesn’t provide adequate relevancy to our study. First of all, the topic of the manuscript fits our topic of investigating the particleboards. And though the binder used in the cited study is different, the raw material for the production of particleboards is primarily relevant to one of the materials we used. But the most relevant justification to cite the study is the IB performed after the boiling, which is investigated only by a few literature sources; we collected the most appropriate ones.

Comment 6. Figure 2 should be removed. It presents data that is also included in Table 3, resulting in unnecessary duplication of results. Furthermore, the graph is difficult to read and does not provide any additional information that would facilitate the interpretation of the results.

Response 6: Thank you for the suggestion. However, in our opinion, Figure 2 provides the results very clearly, including the reference of P3 boards and standard deviations indicating the differences between the board groups. In turn, results in Table 3 primarily represent the IB retention ratio after the boiling treatment based on equation 1.

Comment 7. Figure 8 is also difficult to read; it should be divided into four separate figures: SE, SE-M, SA, and SA-M.

Comment 8. Please standardize the terminology: “boards” or “panels”

Response 8: Thank you for the suggestion. The term “boards” was revised throughout the manuscript.

Comment 9. In their conclusions, the Authors state that the tested GASA and SWSA boards meet the P3 class requirements for IB_boil and TS-boil and can be used in finishing systems; however, in light of the comments presented, this conclusion seems overly broad. The tests conducted do not cover all the properties required for a full assessment of compliance with the requirements of this board class. In particular, the results for bending strength (MOR) and bending modulus of elasticity (MOE) were not presented. Therefore, based on the presented results, it can only be concluded that the tested panels meet the requirements of type P3 with regard to the analyzed properties; however, there is no basis for concluding full compliance with the requirements of this type.

Response 9: Thank you for suggesting to improve our manuscript. This manuscript is intended to present water resistance of developed fully bio-based particleboards for outside applications. As was responded to your valuable comments above, other characteristic properties of the boards were presented in our previous study [33]. So, now, based on these two studies we can claim that our developed boards comply with P3 board requirements as stated in the conclusions. In turn, in the framework of this study, we claim, that the developed SA-based particleboards met not only the IB-boil requirement of P3, but even P5 boards. Furthermore, the developed SA-based finishing systems – particularly those incorporating chitosan and earth pigment – further enhanced water resistance of developed boards.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

All comments are entered into the text.

Author Response

Comments 1: All comments are entered into the text.

Response1: Thank you for review and contribution to improve our manuscript.

Reviewer 3 Report

Comments and Suggestions for Authors

Re-review of the manuscript ID – thermo-4338389

 

Water resistance of fully bio-based particleboard intended for building façade application

 

I would like to thank the Authors for addressing the reviewers’ comments and preparing a revised version of the manuscript. Unfortunately, after reviewing their responses, I find that some of my key comments have not been addressed satisfactorily.

1. First and foremost, I cannot agree with the Authors' opinion regarding the applicability of the research results to P3-class particleboard used as facade boards. This is particularly significant for frame construction, where such boards also serve to stiffen the structure; therefore, they must be structural boards, which P3 boards do not qualify as. According to the EN 312 standard, P3 boards are intended for interior use in humid conditions. Their increased moisture resistance does not imply resistance to long-term exposure to weather conditions or suitability for use as materials for exterior partitions. The term “moisture-resistant” refers to conditions of use inside buildings and is not synonymous with suitability for facade applications.

Even in the case of ventilated facades, the boards used as exterior cladding should be materials specifically designed for such applications, characterized by adequate durability and resistance to repeated cycles of wetting and drying. P3 boards are not designed to perform under such conditions. In construction practice, materials intended for exterior use, such as appropriate boards, are used for exterior wall cladding.

In construction practice, materials intended for exterior use—such as appropriate structural boards, fiberboards, or other products with the proper declarations of use—are used for exterior wall cladding. Therefore, I believe that the Authors should not base their conclusions on P3-class boards or present them as facade boards. As currently worded, this may lead the reader to misinterpret the research results.

2. The Authors did not address my comment regarding Figure 8. Their response contains no comment explaining this issue nor any information about possible changes to the manuscript.

In summary, despite the corrections made and the explanations provided, I believe that the most important substantive comments have not been addressed. For this reason, at this time I cannot recommend publication of the manuscript in its current form and believe that it still requires revision.

 

Recommendations – major revision

 

Comments for author File: Comments.pdf

Author Response

Comments 1: First and foremost, I cannot agree with the Authors' opinion regarding the applicability of the research results to P3-class particleboard used as facade boards. This is particularly significant for frame construction, where such boards also serve to stiffen the structure; therefore, they must be structural boards, which P3 boards do not qualify as. According to the EN 312 standard, P3 boards are intended for interior use in humid conditions. Their increased moisture resistance does not imply resistance to long-term exposure to weather conditions or suitability for use as materials for exterior partitions. The term “moisture-resistant” refers to conditions of use inside buildings and is not synonymous with suitability for facade applications.

Response 1: Sure, we agree with your valuable comment regarding requirements of structural application outside, as our developed particleboards are indeed intended to. We have changed the requirements of P3 to P5 in the manuscript comparing our boards.

Comments 2: Even in the case of ventilated facades, the boards used as exterior cladding should be materials specifically designed for such applications, characterized by adequate durability and resistance to repeated cycles of wetting and drying. P3 boards are not designed to perform under such conditions. In construction practice, materials intended for exterior use, such as appropriate boards, are used for exterior wall cladding.

Response 2: Thank you for the practical comment. We fully agree that the materials intended for exterior application should be specifically designed to meet adequate durability. That’s why we provided the study testing the water resistance of our developed particleboards.

Comments 3: In construction practice, materials intended for exterior use—such as appropriate structural boards, fiberboards, or other products with the proper declarations of use—are used for exterior wall cladding. Therefore, I believe that the Authors should not base their conclusions on P3-class boards or present them as facade boards. As currently worded, this may lead the reader to misinterpret the research results.

Response 3: Thank you for your practical comment. Indeed, we agree that our conclusions should not be based on P3-class boards but on our experimental testing, achieving results that comply with a higher board class than P3. Therefore, to avoid the misinterpretation, an appropriate change has been made in the conclusions.

Comments 4: The Authors did not address my comment regarding Figure 8. Their response contains no comment explaining this issue nor any information about possible changes to the manuscript.

Response 4: We appreciate your suggestion regarding Figure 8; however, we don’t agree about the readability since all the authors accepted the current version. Figure 8 was intentionally presented as a combined plot to allow direct visual comparison of all board types under identical measurement conditions, which would be more difficult to compare if the data were split into four separate figures. We deeply believe that the selection of a graphical presentation demonstrating the results of a water drop depending on different boards' production technologies is a matter of taste, not a wrong choice. In turn, such a choice with one figure is beneficial in terms of length of the manuscript and doesn't impact the quality of the manuscript.

Comments 5: In summary, despite the corrections made and the explanations provided, I believe that the most important substantive comments have not been addressed. For this reason, at this time I cannot recommend publication of the manuscript in its current form and believe that it still requires revision.

Response 5: Thank you for your review and comments intended to improve our manuscript. Now we have addressed all your comments and ask for accepting our manuscript for publication in the journal Thermo.

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

The Authors have fully addressed Recenznet's comments. After making the necessary revisions, I believe the manuscript can be published in its current form.