Mural Paintings Characterisation Using X-ray Fluorescence and Raman Spectroscopy—A Case Study: Nossa Senhora das Neves Chapel, Vilar de Perdizes, Galicia—North Portugal Euroregion

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

 The title " Mural Paintings Characterisation Using Portable Raman Spectroscopy in Galicia-North of Portugal Euroregion" is descriptive and clearly presents the research topic.

The introduction presents a strong rationale for the importance of studying historical wall paintings and how they contribute to the understanding of history and cultural tourism in the framework of the IACOBUS program.

Relevant context is provided by mentioning other studies on mural paintings in Portugal and in the border region with Spain.

The iconographic interpretation of the mural paintings of the Chapel helps to contextualise the research from a historical and interpretative point of view, providing data for a better interpretation of the paintings. The text provides relevant information about the chapel and its relationship with the Marão painting workshops.

 

The location of the pigment samples analysed with portable Raman is clear and aids the understanding of the text, and the number of representative samples of each colour is correct. The figures of the Raman Spectra of colour measurements are adequate and complete the objective of the study.

The analytical techniques used in the characterisation of the wall paintings are listed, which is relevant and shows the scientific basis of the study.

Several critical aspects to consider in the study of wall paintings are mentioned, such as mortar types, pigments, techniques, iconography, among others.

 

Adequate and updated bibliography on the techniques used. Bibliographical references are provided to support the statements made in the text.

Overall, the text presents an important and relevant approach to the preservation and study of historic wall paintings, and is based on a solid scientific foundation. The work provides interesting and fundamental data for future interventions in the conservation of the paintings and for their preventive conservation.

 

 

Author Response

Dear reviewer 1,

I appreciate very much your comments on the manuscript entitle "Mural Paintings Characterisation Using X-Ray Fluorescence and Raman Spectroscopy. Case Study: Nossa Senhora das Neves Chapel, Vilar de Perdizes, Galicia-North of Portugal Euroregion”.

Now I send you a new version of the manuscript expanded with other analytical techniques.

I am very grateful for your comments on this manuscript.

Sincerely yours,

David Martín Freire-Lista and coauthors

Reviewer 2 Report

Comments and Suggestions for Authors

This paper shows the results of the artistic and chemical analysis by portable Raman spectroscopy of a 16th century mural painting from the church of Nossa Senhora das Neves in Vilar de Perdizes (Galicia – 23 North Portugal Euroregion). This work is interesting because of the non-invasive analysis of a cultural heritage that is to be valued and for which there is little information, especially, according to the authors, in order to promote tourist activity. However, some mistakes and missing information are evident, and a major revision is recommended.

·        1) In  the abstract it mentions the use of portable and non-invasive techniques although it is only Raman, it should be more specific, as is its title. Since it is a work that concludes in the determination of pigment composition with only one technique when the heritage is a complex material, and approaches are usually multi-technical.

·         2) The introduction contains a lot of bibliography as in a review and in this case I think it is not necessary. I suggest leaving the most important ones in the area that help the context of the study of this kind of work of art. In addition, the bibliography is misplaced from 101 - 107. Mistakes in the references are evident in the paragraphs on page 11. Throughout the whole work, leave and add only bibliography that supports the arguments and hypotheses generated.

·        3) In the Results section, the results are presented by colour and then by identified compound. First, all the compounds found are considered as pigments, which must be supported by an argument. Then, for most of these compounds, synthetic origin, i.e. manufactured, is considered and the possibility of a natural origin is not considered, which must be supported by arguments or hypotheses.

·        4) the observed bands in the Raman spectrum assigned to a compound must be associated to a reference.

·       5) The Raman spectra are very noisy and there is a lot of effort to assign peaks that cannot be distinguished from this noise. Many compounds I consider their presence to be doubtful, such as jacobsite in the greys and charcoal in the whites and red. I strongly recommend reviewing the related literature.

·        6) Charcoal is not the correct name when observing the bands of the black carbon-based compounds (CB), in the chosen literature there are several papers that specifically define these compounds, so in these analyses the type of CB cannot be identified as charcoal without further analysis. The bands are always quite broad, and this is not the case for the spectra of the targets.

·        7)Hydroxyapatite is clearly not a pigment, it is part of a black paint, called bone black whose presence is proposed from observing bands for CB and bands for Phosphates (960) which corresponds to a rather modified bone-derived hydroxyapatite. This is evidence of the lack of critical reading of most of the papers used in this work as a reference.

·        8)Similar comments arise for the lead target, where they also observe a peak at 140 cm-1 which is outside the range.

·       9)In the spectra for the yellow colour, a band at 985 cm-1 is evident and it is proposed that it is a mixture of pigments based on iron oxides, without foundation or references.

·         10) I do not understand that the conclusions state that the use of lead compounds is not appropriate if we are talking about a 16th century mural. Maybe this could be stated differently if the objective is to alert about their presence for later restoration and conservation work.

Author Response

Dear reviewer 2,

We appreciate very much your comments on the manuscript entitle "Mural Paintings Characterisation Using X-Ray Fluorescence and Raman Spectroscopy. Case Study: Nossa Senhora das Neves Chapel, Vilar de Perdizes, Galicia-North of Portugal Euroregion”, which have been very helpful to improve its quality.

We modified the manuscript following your suggestions. Please find below the changes that we made. We have also answered each of the questions.

Response to comments:

This paper shows the results of the artistic and chemical analysis by portable Raman spectroscopy of a 16th century mural painting from the church of Nossa Senhora das Neves in Vilar de Perdizes (Galicia – 23 North Portugal Euroregion). This work is interesting because of the non-invasive analysis of a cultural heritage that is to be valued and for which there is little information, especially, according to the authors, in order to promote tourist activity. However, some mistakes and missing information are evident, and a major revision is recommended.

•       1) In  the abstract it mentions the use of portable and non-invasive techniques although it is only Raman, it should be more specific, as is its title. Since it is a work that concludes in the determination of pigment composition with only one technique when the heritage is a complex material, and approaches are usually multi-technical.

The reviewer is correct, which is why I have included other elemental and Raman analyses. It was very difficult for me to interpret the portable i-Raman spectra as they were very noisy and I wasted many weeks trying to identify all the bands. After doing analysis with laboratory Raman equipment and doing XRF, the work has been much more comfortable. Thank you very much for your kind contribution.

•        2) The introduction contains a lot of bibliography as in a review and in this case I think it is not necessary. I suggest leaving the most important ones in the area that help the context of the study of this kind of work of art. In addition, the bibliography is misplaced from 101 - 107. Mistakes in the references are evident in the paragraphs on page 11. Throughout the whole work, leave and add only bibliography that supports the arguments and hypotheses generated.

Thank you very much for your valuable review. Indeed, having spectra with so much noise, I have had to search a lot of literature to identify the bands. I have removed a lot of literature that didn't make sense with the final manuscript.

• 3) In the Results section, the results are presented by colour and then by identified compound. First, all the compounds found are considered as pigments, which must be supported by an argument. Then, for most of these compounds, synthetic origin, i.e. manufactured, is considered and the possibility of a natural origin is not considered, which must be supported by arguments or hypotheses.

The reviewer is correct. My lack of experience in this type of analysis has generated errors that I am currently ashamed of. Indeed, I wrote pigments and the term compounds is more correct. There will surely be other errors, due to the lack of time for this review. I hope you understand and are as patient as you were with the first review.

• 4) the observed bands in the Raman spectrum assigned to a compound must be associated to a reference.

I have included references in all assigned bands. Thank you very much for this valuable information. In the first version I obtained the Raman bands from different sources: References and databases. Including the reference after each band, the manuscript improves considerably.

• 5) The Raman spectra are very noisy and there is a lot of effort to assign peaks that cannot be distinguished from this noise. Many compounds I consider their presence to be doubtful, such as jacobsite in the greys and charcoal in the whites and red. I strongly recommend reviewing the related literature.

Indeed the reviewer is correct. As I explained previously, having such noisy spectra, I have tried to identify all the bands. This work has been very laborious, since I was even looking for additives. Fortunately, your review has been accurate and very valuable. I have performed XRF and narrowed down the possible compounds. Jacobsite and lead compounds are not present.

• 6) Charcoal is not the correct name when observing the bands of the black carbon-based compounds (CB), in the chosen literature there are several papers that specifically define these compounds, so in these analyses the type of CB cannot be identified as charcoal without further analysis. The bands are always quite broad, and this is not the case for the spectra of the targets.

I have changed this label. Thank you very much for this comment. I have read amorphous carbon and C-C bands many times. I am sure that the work done is not in vain and the manuscript had improved thanks to your contributions

• 7) Hydroxyapatite is clearly not a pigment, it is part of a black paint, called bone black whose presence is proposed from observing bands for CB and bands for Phosphates (960) which corresponds to a rather modified bone-derived hydroxyapatite. This is evidence of the lack of critical reading of most of the papers used in this work as a reference.

Thank you for your suggestions and kind contributions. I have indeed improved the text.

• 8) Similar comments arise for the lead target, where they also observe a peak at 140 cm-1 which is outside the range.

The reviewer is correct. I have rewritten and expanded the manuscript with new analyzes that corroborate the reviewer's assessments. I am frankly grateful for their contribution and I am convinced that it will not fall on deaf ears.

• 9) In the spectra for the yellow colour, a band at 985 cm-1 is evident and it is proposed that it is a mixture of pigments based on iron oxides, without foundation or references.

The reviewer is correct. I have modified the text of the manuscript.

• 10) I do not understand that the conclusions state that the use of lead compounds is not appropriate if we are talking about a 16th century mural. Maybe this could be stated differently if the objective is to alert about their presence for later restoration and conservation work.

The reviewer is correct. I have modified the text of the manuscript.

I hope that the improvements introduced in the manuscript provide more scientific rigor and allow this manuscript to be published. However, I am sure that any other comments you may wish to make will serve to improve the manuscript. We are very grateful for your comments on this manuscript.

Sincerely yours,

David Martín Freire-Lista and coauthors

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Authors present a paper on a case study, which should be qualified in the title of the paper. In addition, several considerations must be taken into account before the paper is published. Therefore, my recommendation is Major Revisions.

Lines 26 and 27, "Pigments used..." the formula for the phrases is repeated, it is recommended to clean up the translation.

In the introduction, between lines 37-77, 83 references are introduced, this is not a review article. It is advisable to reduce the number of references, as many of them probably do not contribute anything and are not discussed in the document. Please focus only on those that are related and highlight why they have been selected. 

The objective of the article is lost in the introduction. Clarify this point.

A spectroscopic analysis of the different colours selected is carried out, which is of interest for rehabilitation work. However, the results presented are not discussed and are not compared with other research. What are the implications of the work done, as presented, the results are very poor and seem more like a technical report than a scientific article.

Point 4. Discussion has been omitted from the paper.

The conclusions are very poor and need to be improved. In addition, limitations and future lines of work should be included.

Comments on the Quality of English Language

The translation should be revised throughout the manuscript.

Author Response

Dear reviewer 3,

We appreciate very much your comments on the manuscript entitle "Mural Paintings Characterisation Using X-Ray Fluorescence and Raman Spectroscopy. Case Study: Nossa Senhora das Neves Chapel, Vilar de Perdizes, Galicia-North of Portugal Euroregion”, which have been very helpful to improve its quality.

We modified the manuscript following your suggestions. Please find below the changes that we made. We have also answered each of the questions.

 

Response to comments:

Authors present a paper on a case study, which should be qualified in the title of the paper. In addition, several considerations must be taken into account before the paper is published. Therefore, my recommendation is Major Revisions.

Thank you very much for your wise advice to improve this manuscript. You are indeed correct when you indicate that this work is a case study. It is for this reason, and following your review, I have modified the title: Mural Paintings Characterisation Using X-Ray Fluorescence and Raman Spectroscopy. Case Study: Nossa Senhora das Neves Chapel, Vilar de Perdizes, Galicia-North of Portugal Euroregion

Lines 26 and 27, "Pigments used..." the formula for the phrases is repeated, it is recommended to clean up the translation.

The authors have improved the text and eliminated redundancies, thank you very much for your careful review.

In the introduction, between lines 37-77, 83 references are introduced, this is not a review article. It is advisable to reduce the number of references, as many of them probably do not contribute anything and are not discussed in the document. Please focus only on those that are related and highlight why they have been selected. 

Fortunately, the reviewer has done his job consistently and his comments coincide with those of another reviewer. The authors have eliminated references that were not directly related to the manuscript. We have reduced references by more than 50%.

The objective of the article is lost in the introduction. Clarify this point.

The authors have clarified this point in the introduction.

A spectroscopic analysis of the different colours selected is carried out, which is of interest for rehabilitation work. However, the results presented are not discussed and are not compared with other research. What are the implications of the work done, as presented, the results are very poor and seem more like a technical report than a scientific article.

Thank you very much for your constructive review. The authors have expanded the analyzes carried out on the samples and therefore considerably expanded the manuscript.

Point 4. Discussion has been omitted from the paper.

The authors have added this fundamental section in a scientific article.

The conclusions are very poor and need to be improved. In addition, limitations and future lines of work should be included.

The authors have expanded the conclusions due to the incorporation of new analytical techniques.

I hope that the improvements introduced in the manuscript provide more scientific rigor and allow this manuscript to be published.

We are very grateful for your comments on this manuscript.

Sincerely yours,

David Martín Freire-Lista and coauthors

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The new version of the manuscript is a better version, all my previous comments have been answered. They have added another technique, XRF, to strengthen the Raman results.

I understand that this type of analysis takes a lot of time and dedication, it is, at present, an area in which training and experience is needed. All this is required in all scientific fields and writing involves a great deal of dedication, as scientific rigour is necessary if the potential readers of the work are to be taken into account.

I consider that this work can be accepted after minor revisions:

1) check the use of the abbreviation XRF and define it correctly at the beginning.

2) Re-consider relevant literature references for Raman band assignments, i.e. consider spectroscopy, physicochemistry papers, which are fundamental to the assignment. Do not use just any applied paper. 

3) in figure 9, the Raman spectrum of G shows at 1068 the label "Hdxa" I think it is Calcite. 

 

Author Response

Dear reviewer 2,

We appreciate very much your comments on the manuscript entitle "Mural Paintings Characterisation Using X-Ray Fluorescence and Raman Spectroscopy. Case Study: Nossa Senhora das Neves Chapel, Vilar de Perdizes, Galicia-North of Portugal Euroregion”, which have been very helpful to improve its quality.

We modified the manuscript following your suggestions and we answered each of the questions.

I understand that this type of analysis takes a lot of time and dedication, it is, at present, an area in which training and experience is needed. All this is required in all scientific fields and writing involves a great deal of dedication, as scientific rigour is necessary if the potential readers of the work are to be taken into account.

I consider that this work can be accepted after minor revisions:

Check the use of the abbreviation XRF and define it correctly at the beginning.

Thank you very much for your kind review, I have already corrected the typo and included the abbreviations in the correct place.

2) Re-consider relevant literature references for Raman band assignments, i.e. consider spectroscopy, physicochemistry papers, which are fundamental to the assignment. Do not use just any applied paper.

 

I have introduced specific references to assign the Raman bands. Thank you very much for your help.

3) in figure 9, the Raman spectrum of G shows at 1068 the label "Hdxa" I think it is Calcite. 

Indeed, there was an error in the assignment of that band. Thank you very much for your help, which has helped improve the quality of this manuscript.

Sincerely yours,

David Martín Freire-Lista and coauthors

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have significantly improved the quality of the submitted manuscript. However, some minor revisions are recommended before publication.

A flowchart would help clarify the methodology.

Figure 4,5 and 9, should include letters (a), (b), (c)...below each image to facilitate identification.

The quality of the graphics continues to be greatly improved.

The bibliography continues without being in format.

Author Response

Dear reviewer 3,

We appreciate very much your comments on the manuscript entitle "Mural Paintings Characterisation Using X-Ray Fluorescence and Raman Spectroscopy. Case Study: Nossa Senhora das Neves Chapel, Vilar de Perdizes, Galicia-North of Portugal Euroregion”, which have been very helpful to improve its quality.

We modified the manuscript following your suggestions and we answered each of the questions.

The authors have significantly improved the quality of the submitted manuscript. However, some minor revisions are recommended before publication.

A flowchart would help clarify the methodology.

Thank you for your good appreciation, I have modified the methodology and the manuscript has improved considerably.

Figure 4,5 and 9, should include letters (a), (b), (c)...below each image to facilitate identification.

The authors have been thinking about modifying the nomenclature of the graphs. We have concluded that they are more intuitive if the images are named with the initials of the colour. In this sense there will be fewer letters and we believe that it is positive for the reader.

The quality of the graphics continues to be greatly improved.

The quality of the graphics has been improved and the font size of the labels has been increased to make them easier to read.

The bibliography continues without being in format.

The bibliography has been completely reviewed.

Sincerely yours,

David Martín Freire-Lista and coauthors