Analytical Study of Polychrome Clay Sculptures in the Five-Dragon Taoist Palace of Wudang, China
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsComments to Authors:
Dear authors, I have carefully read your paper "Analytical Study of Polychrome Clay Sculptures in Five-Dragon Taoist Palace of Wudang, China", that was submitted for the publication in Coating journal. I recommend the publication only after a major revision of the content.
1. Introduction
The state of the art, in the introduction, is reduced. Only the first paragraph mentions the importance of the study of pigment and technologies. Moreover, no bibliographical references are mentioned in this part. I strongly advise to extend the introduction and to mention previous studies related to this argument. Also in the following paragraphs references are missing.
I personally suggest removing some specific information about the works of art under consideration from the introduction. The references "Figure 1" should not appear. It could be added in the materials and method section before the in-situ analysis.
I recommend using the past tense to describe the results except for describing images
When a compound is mentioned for the first time it is necessary to add its chemical formula.
A revision of English language is required
Material and methods
2.2.1. Remove the full stop in the first sentence
2.2.2. Specify which objective was used for the analysis
3.1. Correct spelling error “calium”and “premitted”
Remove the full stop between dyes and but. Check the orthography in all the manuscript.
Results
“The orange-red colour in both the up and bottom layers of sample #R-2 contains Pb, indicating that the orange-red colour results in minium (Pb3O4)” This sentence is a speculation and it should be changed. Only you can say that the use of a lead pigment is assumed using SEM-EDS. Move this sentence when describing Raman results
“Figure 2(q) reveals irregular and non-spherical morphology of mercury-rich particles, suggesting the use of natural mineral cinnabar” Please add a reference where you confirm this statement.
The names of the identified compounds must be included in all captions.
Page 8: “In figure 4(a)”: Is the figure 3 not 4
Figure 4 a: From the intensity of the band at around 1300 cm-1 it would seem that the spectrum of hematite from the sample was recorded with the 532 nm laser. Please add the measurement conditions of each spectrum in the caption.
What compound does the first spectrum in figure C belong to? In my experience this spectrum could be the result of the degradation of a lead-based pigment. I suggest these articles to learn about the original bands of lead pigments and their shift when they are analysed with too high laser power using Raman spectroscopy.
- Raman spectroscopy as a means for the identification of plattnerite (PbO2), of lead pigments and of their degradation products
- Use of Temperature Controlled Stage Confocal Raman Microscopy to Study Phase Transition of Lead Dioxide (Plattnerite)
Lead compound analyses should be performed with low laser power to avoid peak broadening and band shifts. The Raman bands of minium do not correspond to those cited in the bibliography.
In the same paragraph the cinnabar bands are mentioned once at 354 and 342 cm-1. Please check the correct position of the Raman bands.
In the figure 4 (i) indicate in the spectrum from the sample to which compounds the bands correspond if it is a mixture.
“However, calcite (CaCO3), which is commonly applied as a white base layer for mural painting and portraits in north China” add reference.
-muscovite (KAl2(AlSi3O10)(OH)2) and Hydro cerussite, Pb3(CO3)2(OH)2)… Mention the XRD image in the text.
“Elemental analysis shows that both layers contain Cu and Cl, indicating that they are composed of basic copper chlorides.” Change “indicating” with “suggesting”.
“Raman analysis shows that the peak shapes of the two layers are basically the same”. It is not appropriate to talk about the “shape of the peak”. I would say that it is the same Raman spectrum if the position of the bands correspond.
“The peaks appeared at 3347(s) cm-1 and 3324(sh) cm-1 in Figure 4(i) correspond to hydroxyl stretching, suggesting that atacamite is also mixed with botallackite”. did you mean the 4 k figure? I only see one band in the spectrum from the sample. Could you indicate the wavenumbers in the image?
“EDS analysis shows that the blue particles in #B-1 mainly contain Si, K, As, and Co, indicating the presence of smalt” As above, you cannot indicate the presence of a compound by elemental analysis alone
“Raman spectroscopy analysis of #B-1(Figure 5(n)) shows a peak at 490 cm-1, corresponding to tetrahedral SiO4 bridging vibration” According to the literature, mentioned tetrahedral SiO4 shows other Raman band, the most intense at about 1096 cm-1. The Raman spectrum presented does not have good resolution and it is difficult to identify the bands. Furthermore, the most defined one appears at around 1300 cm-1. Clarify this assumption.
The layer beneath the dark blue pigment (#B-1) is composed of lead white. Specify that it was identified with XRD
“Raman spectra suggest the possible use of indigo”. What is the spectrum? Mentioned the figure.
“The presence of K suggests the addition of wood ash, while the presence of As, Fe, Bi, and Ni can be attributed to the diverse sources of cobalt minerals in Germany” These statements seem risky to me. They should at least be contrasted with the bibliography.
Improve SEM images (Figure 6). Some can't be seen well.
Conclusions
“Heated tung oil is used to attach the gold foil, and underneath is a coating of black carbon and red lead white.” Red lead or white lead?
Comments on the Quality of English LanguageThe use of English language shuold be improved
Author Response
Dear reviewer
Thank you for your careful reading and professional comments, which help us improve the quality of this article. We extensively revised our manuscript according to your comments.
Please find the report in the attachment and revised manuscript.
Thank you.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsIt is a very nice and very interesting study. The authors present the analysis of the painting materials and the techniques used in two tall polychrome sculptures (named Qinglong (Azure Dragon) God and Baihu (White Tiger) God) through multiple characterization methods.
My main concern is that if the objective is the analysis of the materials and pictorial techniques used in these sculptures, the authors must complete/analyze the results of the organic part, the binder. The analysis of the pigments is very well done.
Other comments:
2.2. Sampling Materials and Experimentals
It is necessary to indicate on what basis the samples were selected
2.2.5. Micro-FTIR Spectroscopy
Was total or external reflection measured?
How was the data processed?
Page 8 last paragraph
In “Figure 4(a)” it should be “Figure 3(a)”
Page 13 (Figure 6 ())
Something is wrong
Pag 13 “corresponding to the ester carbonyl ν(C=O) band in 1735–1730 cm−1 and the characteristic ν(C-H) bands at 2926–2919 cm−1 and 2858–2850 cm−1.”
I do not see the bands of 1735–1730 cm−1 in the figure, please review or enlarge
3.3. Organic Materials
There are bands that are indicated and do not seem like bands and there are others that are not assigned. Please check this part.
Pag 15
Why can't the L-Proline be seen in the IR? review/discuss
Discussion “mixed with fibers to reduce the shrinkage of the white base layer during drying,”
Shouldn't they be seen in SEM?
Author Response
Dear reviewer:
Thank you for your careful reading and important comments. We have revised the text according to your comments and made overall language editing.
Please check our response in the attachment and the revised manuscript uploaded.
Thank you.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe article examines samples of painting materials from a Taoist temple, which are one of the unique examples of sculpture. To determine the type of materials used in painting, the authors used a fairly large number of different unique methods, which allowed them to establish the types of pigments used in the process of making sculptures. In general, this study is quite interesting and informative, and the results obtained are highly significant not only from a fundamental point of view, but also from a technological point of view, since the results obtained allow us to obtain more data on materials used previously, which also allows us to determine the level of technological development in the past. However, before this work can be accepted for publication, the authors should answer a number of clarifying questions from the reviewer.
1. As is known, when recording Raman spectra under the influence of a laser, processes of structural changes can occur if the materials have a low melting point; in this regard, the authors of the work should give a small explanation of whether this factor was taken into account when recording Raman spectra.
2. On a technical issue, the samples under study have a clearly uneven surface and are quite large, which raises the question of how the X-ray diffraction patterns of these samples were measured, and how these irregularities were taken into account in the shift of reflections in the diffraction patterns.
3. Inclusions in the form of copper and chlorine presented in Figure 4 reflect the presence of each element separately or in the form of a chloride compound? It should also be noted that the established quartz phases reflect the presence of oxygen in the composition of the samples, however, the mapping results are presented without an oxygen distribution map.
4. Do the proposed diagrams in Figure 10 have evidence in the form of archival data on methods for applying coatings to sculptures, or is this a proposal from the authors?
Author Response
Thank you for your careful reading and important comments. We have revised the text according to your comments and made overall language editing.
Please find our response in the attachment and the revised manuscript.
Thank you.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsAlthough some experiments have been performed and the artwork is one of the most important in China, some serious flaws have been detected along the entire text of the article.
- Abstract and the entire text: Vermilion is employed for synthetic and cinnabar for natural
- Location of the sampling should be shown in the Figure 1c
- An explanation about Table 1 is necessary in section 2.2
- Samples were collected only from one sculpture? Why?
- What about the detector of Raman spectrometer?
- Samples were not metallised for doing SEM analyses?
- Semiquantitative analyses must be provided from XRF portable system, using PyMCA or other similar softwares
- Fe is not shown in Figure 2, why?
- Figures 2m-2r are not described in the legend of Figure 2
- Why do you mention metacinnabar and hypercinnabar?
- Gypsum used as a binder? Or as a support material?
- Some references are necessary when comparing with Chinese artworks
- Cerussite sould be found together with hydrocerussite
- The presence of atacamite was proven from the results of Figure 4k? Revise
- Reference spectra of smalt and indigo must be added in Figures 5n and 5m, respectively. I am not very sure about the presence of these pigments and colourants
- Table 2 is not mentioned in the text.
- Golden gilding?
- Accurate composition of all the components (gilding preparation layer, binders, etc.) must be provided
- EDX results of black are not described
In general, results must be more discussed with literature and the findings compared with literature.
About the discussion, it should be notably improved. What about gilding methods, for instance?
Comments on the Quality of English LanguageThe text should be revised by a English native speaker
Author Response
Dear reviewer
Thank you for your careful reading and professional comments, which help us improve the quality of this article. We extensively revised our manuscript according to your comments.
Please find our report in the attachment. Thank you.
Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for AuthorsReview attached
Comments for author File: Comments.pdf
Author Response
Dear Reviewer
Thank you for your careful reading and professional comments, which help us extensively improve the quality of this article. We revised our manuscript according to your comment.
Please find our report in the attachment. Thank you
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors1. please remove references to figures in the introduction (Figure 1 (a)) first line in of the introduction). Usually the case of the study images are mentioned in the methodology or results part.
2. Please, revise the English language or choose more appropriate terms in particular in the new paragraphs. For instance : foreign pigment, in the introduction, with “pigment from other countries”, “different representative colors were chosen for the samples used” replace with “samples with different tones were chosen”etc...
3. As I had previously written, attention must be paid to the identification of lead based pigments. The bands belonging to minium that are mentioned in the article are not correct as this compound shows the main Raman bands at 120, 390 and 550 cm-1 among others. The spectrum attributed to minium is probably that of a lead compound degraded by laser power. Similarly, as I have already indicated, the first spectrum of image 3c corresponds to a compound degraded by laser power during analysis, so the band at 251 may not belong to cinnabar. In fact, the difference between this spectrum and the one shown in figure 3e are very different.
The Raman spectra in image 3c are not correctly assigned because they belong to compounds degraded during analysis and cannot be published. As I am familiar with the behaviour of lead pigments when analysed by Raman spectroscopy, I recommend repeating the analysis of this sample.
Comments on the Quality of English LanguageThe English Language must be revise.
Author Response
Dear Reviewer:
Thank you for your careful reading and professional suggestions. We have modified the manuscript following your suggestions. Please check our resubmitted version and find the reply in the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors made all the requested changes, in my opinion the manuscript can now be published
Author Response
Dear reviewer:
Thank you very much for your comments and professional suggestions. These opinions help us a lot to improve the quality of our manuscript. Based on your suggestions, we had made modification on the section of organic materials. This time, the English language were re-edited deeply and some details of the results (Raman spectroscopy) were updated.
Hope you could find more details in our revised manuscript.
Thank you.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors have been a great effort to improve your work, specially in the discussion of the results.
They have correctly anwered and added some paragrpahs after my recommendations.
If editors agree, I do not have any reason to reject the paper. For me, it could be published after some English review.
Comments on the Quality of English LanguageA deep review of English should be done.
Author Response
Dear reviewer：
Thank you for your comment and the professional suggestion help us greatly improved the quality of our manuscript.
Before the previous submission, we had asked a professional language agency (MDPI author services) to edit English language. This time we asked a native English speaker to review the English details again and asked for a re-edit service for the changed manuscript.
We hope the quality of the English language of the revised version could have been improved.
Round 3
Reviewer 1 Report
Comments and Suggestions for AuthorsI had previously rejected the manuscript in the last form sent to me because, in my experience, two Raman spectra had not been correctly assigned. In the last version I viewed, only one spectrum had been changed, and the lead red spectrum does not correspond to the one mentioned in the bibliography. I would like to know where the lead red spectrum they use as a reference comes from. The spectrum they included, both as a reference and recorded in the sample does not appear in the bibliography recorded with the 785 nm laser. Instead, it is mentioned when the compound is analysed with the 532 nm laser. Therefore, the authors should change the wavelength of the laser in the image and explain in the text that the intensity of the bands may vary depending on the measurement parameters, especially the laser to which the lead red is analysed.
I recommend also including a bibliography reference where lead red is analysed with the 532 nm laser in addition to the bibliography references where lead red appears analysed with the 785 nm laser already included in the text- A combined theoretical and experimental investigation of the electronic and vibrational properties of red lead pigment.
I hope my comments can be passed on to the authors. Comments on the Quality of English Language
none
Author Response
Dear reviewer:
Thank you for your professional review and for pointing out this significant problem about the lead red spectrum.
We repeated then Raman spectroscopy analysis and changed the image.
Please find more details in the attachment and our revised manuscript.
We hope this revision corrected the previous mistakes of Raman analysis on minium.
Thank you again for your professional instructions.
Author Response File: Author Response.pdf
