Wood Surface Changes of Heat-Treated Cunninghamia lanceolate Following Natural Weathering

Round 1

Reviewer 1 Report

Introduction-

Seems adequate. However in line 47 “Earlier research generally examined the resistance of heat-modified wood to artificial weather  [10–16].” A description of the findings should be included since it is relevant to this paper.

Material and methods

Please state the equipment used for color measurements

Results and discussion

Line 129 “…groups that were oxidized to carbonyl groups that were oxidized to carbonyl groups and carboxyl….” Please rephrase

The initial b* value for HT 190ºC (figure 1) seems to be much higher than the expected which originates a sharp decrease in just one day. Is this value correct?

Also, please check the a* values because the first two days show a sharp increase followed by a sharp decrease which is odd. Perhaps you should present the standard deviations to understand the results.

I am not familiar with the “Wilcoxon signed ranks test” but it is odd that it shows a better stability for HT 190ºC.

Line 180 to 183 – The way that this description is made it seems that there were actual results from this work. Please rephrase, since your results cannot support this conclusions.

Line 199 “Both heat-treated and untreated wood surfaced wood surfaces were..” Rephrase

Line 282 “Lignin was always the most ???? chemical component in weathering” something is missing.

Line 285 “The more obvious the decay phenomenon happened in the  corresponding anatomical position under natural exposure.…” Sorry, did not understand.

Line 292 “prevent erosion caused by microorganisms and insects” degradation would be a better word.

Line 295 “ corrosion..”  The same as before. Corrosion involves metals.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The authors considered an interesting scientific problem of natural weathering of thermally modified Chinese fir wood. The presented findings seem to be novel. I find the study as interesting. The paper is well structured and written. The section “Introduction” approaches the scientific problem being solved in the study. The discussion of the obtained results is thoroughgoing. The conclusions are well derived and constructed.

However, some drawbacks and uncertain descriptions were found in the manuscript.

I would suggest to modify the title of paper. In my opinion a fragment “…Natural Exposure” is not informative enough. As the study deals with natural weathering of thermally modified wood it would be much better to replace a word “Exposure” with “Weathering”. Please add some more details on processes of thermal modification. Was it made in superheated steam or oil? What was the moisture content of wood subjected to the treatment? It would be important to put some details on factors and intensity of weathering in subsection “Natural Weathering Conditions”. I would expect additional information on the experiment. It would be helpful for readers to compare conditions of the process with other artificial weathering experiments. Section “2. Materials and Methods” – please put the information that all experiments, i.e. color measurements and microscopy investigations were made for the same time schedule. Microscopic pictures are very small now. It considers pictures in Figure 4. One has to make huge zoom within the PDF file to follow the described anatomical changes. Is it possible to paste some bigger pictures?

Author Response

Response to Reviewer 2 Comments

Point 1: I would suggest to modify the title of paper. In my opinion a fragment “…Natural Exposure” is not informative enough. As the study deals with natural weathering of thermally modified wood it would be much better to replace a word “Exposure” with “Weathering”. 


Response 1: Title: “Wood Surface Changes of Heat-Treated Cunninghamia lanceolate Following Natural Weathering”

Point 2: Please add some more details on processes of thermal modification. Was it made in superheated steam or oil?

Response 2: Line 72, “Lumber was heat-treated at 190°C and 220°C for 120 min, respectively under steam.”

Point 3: What was the moisture content of wood subjected to the treatment?

Response 3: Line 76, “Timbers were dried to a moisture content of 8% prior to the steam-heat treatments. About 4% moisture content was achieved after the steam-heat treatments.”

Point 4: It would be important to put some details on factors and intensity of weathering in subsection “Natural Weathering Conditions”. I would expect additional information on the experiment. It would be helpful for readers to compare conditions of the process with other artificial weathering experiments.

Response 4: Line 82-84, “The statistics mean temperature, humidity, duration of sunshine, total rainfall and wind speed were 30.01±1.41°C, 67.81±6.31%, 9.13±3.57 h, 1.68 mm, and 2.92±0.80 m/s, respectively.”

Because it was not raining every day, the average value of rainfall was only taken.

Point 5: Section “2. Materials and Methods” – please put the information that all experiments, i.e. color measurements and microscopy investigations were made for the same time schedule.

Response 5: Line 208, “It was found that microstructure did not change in the first two days of natural weathering, until after 4 days had a little change (shown in Figure 4g).”

Pictures of the surface exposed after 4 days was added to Figures 3 and 4. The surface microstructure did not change after 1 day and 2 days of exposure, so it was not shown.

Point 6: Microscopic pictures are very small now. It considers pictures in Figure 4. One has to make huge zoom within the PDF file to follow the described anatomical changes. Is it possible to paste some bigger pictures?

Response 6: Line 246-251. The size of the photos was also taken into account, only showing the most representative microscopic photos.

Author Response File: Author Response.docx