Influence of Thermal Modification in Nitrogen Atmosphere on Physical and Technological Properties of European Wood Species with Different Structural Features
Round 1
Reviewer 1 Report
Comments
1) Title very long
2) Abstract: The effect of varnishing instead of The effect of finishing
3) Abstract : Any percentages to be added to show the importance of the comparision between the nature of woods
4) Keywords : ok
5) Introduction: please add references literature studies of previous works on the same subject to show clearly the state of the art of your work.
6) Results need more discussions to emphasize the importance of Thermal modification of wood.
Table 1 (Black poplar)
confusion (finishing and varnishing)
7) References: fellow the coating template and update them by adding 2022,
With regards
Author Response
Dear Reviewer
Answer:
Thank you very much for your valuable comments. The article was corrected and changes are marked in green. The linguistic correction of the text is marked in grey.
Title
- The title is very long.
Answer:
In our opinion, the title is very appropriate to the content of the article and very informative. To make the title a bit simpler, we have removed the word "selected".
Changes introduced in the text (page 1, lines 2-4): Influence of Thermal Modification in Nitrogen Atmosphere on Physical and Technological Properties of European Wood Species with Different Structural Features.
Abstract
- The effect of varnishing instead of The effect of finishing.
Answer:
Changes introduced in the text (page 1, line 16): In particular, after varnishing, there was a significant increase in gloss and a radical change of colour.
- Any percentages to be added to show the importance of the comparison between the nature of woods.
Answer:
In our opinion, the Abstract is very extensive and describes the most important relationships among several dozen variants of the tested wood samples. In order to provide more detail, the following was written: Thermal modification reduced the Brinell hardness of wood with wide rays (oak and beech) by 11%. Changes introduced in the text (page 1, lines 25 - 26).
Keywords
- ok
Introduction
- Please add references to literature studies of previous works on the same subject to show clearly the state of the art of your work.
Answer:
Changes introduced in the text (pages 2-3, lines 95-107): For modified wood with significantly changed properties, the knowledge about the surface improvement processes and the results (effectiveness) of these measures is still incomplete. In particular, there are no reports on the technological properties of thermally modified wood in a nitrogen atmosphere, especially those finished with different coatings. The colour stability of thermally modified wood in overheated steam and covered with various types of coatings was widely analyzed [37,38]. The influence of wood heat treatment and coatings on hardness, scratch resistance [39], and abrasion resistance [40] was investigated. It should be noted that this type of research was not carried out on thermally modified wood in a nitrogen atmosphere, especially in such a wide range of wood species with different morphological features. Therefore, the aim of the study was to determine the effect of heat treatment in a nitrogen atmosphere, covered with oil and varnish, on selected physical and technological properties of European wood species with different structural features.
Results
- Need more discussions to emphasize the importance of Thermal modification of wood.
Answer:
Discussion (pages 6-7, lines 252 - 266): During the heat treatment process hemicelluloses as first change their structure. The deacetylation process conducts to create an acetic acid which indicates the depolymerisation process [50,51]. Most of the extractives disappear or degrade but appear as new ones as degraded products from other decomposition of other structural components of wood [52]. Due to chemical changes occurring during modification at high temperatures, thermally treated wood, regardless of the species or type of structure, shows a lower equilibrium moisture content (EMC) compared to native wood [14,15,53-55]. The lower moisture content of TM wood contributes to the observed higher absorption of agents. Regardless of this, no differences were observed in the curing (drying) process of oil and varnish coatings on native and TM wood. The second important factor affecting the greater absorption of agents, which translates into a higher application rate, is the lower density of TM wood as a result of mass loss, which is a consequence of chemical changes occurring during modification at high temperatures. Wood with a lower density is characterized by a greater surface porosity and roughness which are increased after heat treatment [56] and has less surface free energy [57-59].
Discussion (page 9, lines 328 - 335): Thermal modification affects the colour of the wood [40,60,61]. During thermal modification, mainly hemicelluloses are degraded. Organic acids such as acetic acid and formic acid are produced in parallel. It was stated that these acids influence the darkening of wood [62]. Additional use of acidic varnish coatings may cause darkening of the wood [63]. Coatings can also react with wood components, which can affect the final colour of the wood. The greatest changes were observed for the L* parameter [60,64]. In the case of a* and b* parameters, different directions of changes were observed, which depend on many factors, i.e. wood species, and the modification process parameters.
- Table 1 (Black poplar)
Answer:
We have given the names of wood species in accordance with the provisions of EN-13556: 2003 standard [41]. According to the guidelines of the standard, black poplar should be written with lowercase letters.
- Confusion (finishing and varnishing).
Answer:
We analyzed the text of the entire article and made the necessary corrections. We found the indicated inaccuracy in the Materials and Methods section. Changes introduced in the text (page 4, lines 157 - 161): A three-component system was used for varnishing: Fondo UV118 (undercoat, one application), Fondo UV320 (undercoat, two applications) and Finitura UVR75-G30 (coat, two applications) - producer Chimiver (Via Bergamo, Italy).
References
- Fellow the coating template and update them by adding 2022.
Answer:
Unfortunately, there are not too many papers about our topic. We again checked the “Web of knowledge core collection” base and wrote keywords like e.g. coatings wood, heat treatment – in 2022. We found only 12 articles. No one is suited to our research. We found articles published in 2021 and added them to the Introduction section as you pleased (Changes introduced in the text (pages 2-3, lines 95-107)).
Yours sincerely
Authors
Reviewer 2 Report
The manuscript needs some major improvements before publication.
I suggest simplifying the title ("nitrogen atmosphere", "selected" is not needed in the Title.
The Abstract: Please mention 5 wood species in the first sentence in the Abstract, also with Latin names.
The Introduction:
Line 31: this sentence is not completely true, please modify it.
Line 43: Please add newer information.
Lines 46-49: Please add some references.
The introduction is very general and most well known, authors should focus on wood species used in this research, their influence on physical and technological properties, discuss more deeply why they used nitrogen atmosphere, and discuss different structural features (this should be explained in the Abstract).
The Materials and methods and Results part is well written.
I have one major concern and it is the novelty of this research, as all these 5 wood species are well researched in the case of TM wood. Please explain the novelty properly.
Author Response
Dear Reviewer
- The manuscript needs some major improvements before publication.
Answer:
Thank you very much for your valuable comments. The article was corrected and changes are marked in green. The linguistic correction of the text is marked in gray.
- I have one major concern and it is the novelty of this research, as all these 5 wood species are well-researched in the case of TM wood. Please explain the novelty properly.
Answer:
Changes introduced in the text (pages 2-3, lines 95-107): For modified wood with significantly changed properties, the knowledge about the surface improvement processes and the results (effectiveness) of these measures is still incomplete. In particular, there are no reports on the technological properties of thermally modified wood in a nitrogen atmosphere, especially those finished with different coatings. The colour stability of thermally modified wood in overheated steam and covered with various types of coatings was widely analyzed [37,38]. The influence of wood heat treatment and coatings on hardness, scratch resistance [39], and abrasion resistance [40] was investigated. It should be noted that this type of research was not carried out on thermally modified wood in a nitrogen atmosphere, especially in such a wide range of wood species with different morphological features. Therefore, the aim of the study was to determine the effect of heat treatment in a nitrogen atmosphere, covered with oil and varnish, on selected physical and technological properties of European wood species with different structural features.
Title
- I suggest simplifying the title ("nitrogen atmosphere", and "selected" is not needed in the Title.
Answer:
In our opinion, the title is very appropriate to the content of the article and very informative. To make the title a bit simpler, we have removed the word "selected".
Changes introduced in the text (page 1, lines 2-4): Influence of Thermal Modification in Nitrogen Atmosphere on Physical and Technological Properties of European Wood Species with Different Structural Features.
Abstract
- Please mention 5 wood species in the first sentence in the Abstract, also with Latin names.
Answer:
Changes introduced in the text (page 1, lines 10-12): The wood of five European species: black poplar (Populus nigra L.), European beech (Fagus sylvatica L.), European ash (Fraxinus excelsior L.), European oak (Quercus robur L.), Scots pine (Pinus sylvestris L.) was subjected to thermal modification in a nitrogen atmosphere at 190 °C during 6 h.
Introduction
- Line 31: this sentence is not completely true, please modify it.
Answer:
Changes introduced in the text (page 1, lines 32-33): Thermal modification of wood is the process conducted in an oxygen-free environment in the temperature range from 160 °C to 260 °C [1].
- Line 43: Please add newer information.
Answer:
Changes introduced in the text (page 1, lines 43-44): The global commercial production of modified wood is about 1 MM m3/year [8].
- Lines 46-49: Please add some references.
Answer:
Changes introduced in the text (page 2, lines 46-47): An important factor determining the course of the modification process and consequently the properties of wood is the temperature [9,10].
- The introduction is very general and well-known, authors should focus on wood species used in this research, and their influence on physical and technological properties, discuss more deeply why they used nitrogen atmosphere, and discuss different structural features (this should be explained in the Abstract).
Answer:
Changes introduced in the text (pages 2-3, lines 95-107): For modified wood with significantly changed properties, the knowledge about the surface improvement processes and the results (effectiveness) of these measures is still incomplete. In particular, there are no reports on the technological properties of thermally modified wood in a nitrogen atmosphere, especially those finished with different coatings. The colour stability of thermally modified wood in overheated steam and covered with various types of coatings was widely analyzed [37,38]. The influence of wood heat treatment and coatings on hardness, scratch resistance [39], and abrasion resistance [40] was investigated. It should be noted that this type of research was not carried out on thermally modified wood in a nitrogen atmosphere, especially in such a wide range of wood species with different morphological features. Therefore, the aim of the study was to determine the effect of heat treatment in a nitrogen atmosphere, covered with oil and varnish, on selected physical and technological properties of European wood species with different structural features.
In the Abstract we wrote (page 1, lines 20-27): In the case of the thickness of varnish coatings, the wood structure was important, i.e. on ring-porous hardwood and softwood they were thicker. In the case of wood species with a lower density, i.e. black poplar and pine, the thermal modification in the nitrogen atmosphere process did not reduce the resistance of the varnish coat, and in the case of species with a higher density (oak, ash, beech) it decreased by one level. Thermal modification reduced the Brinell hardness of wood with wide rays (oak and beech) by 11%. The applied process of surface finishing by double varnishing or oiling did not significantly change the hardness of the tested wood.
Materials and Methods, Results sections
- The Materials and methods and Results part is well written.
Answer:
Thank you very much for your comments.
Yours sincerely
Authors
Round 2
Reviewer 2 Report
Authors improved the manuscript.
