GLAZE EFFECTS—Analytical Approaches for Documentation and Conservation Assessment of a Contemporary Tile Panel

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper “GLAZE EFFECTS - analytical approaches for documentation and conservation assessment of a contemporary tile panel” deals with a very interesting and original topic, promoting the attention of heritage science studies to contemporary artistic glazes.

Even if the study is focussed only on one case study, the objectives and methods are well and clearly described; the use of experimental replicas is particularly suited for this type of studies and should be praised.

However, I have a few concerns about the use of XRF spectroscopy, believing that the results are not adequately commented. My main concern regards the quantification method and the interpretation of maps on such irregular samples. Regarding the quantitative analysis, there is only a quick mention at line 127. More details should be provided (at least saying whether the internal analysis software of the instrument was used or other softwares). Moreover, a short review of the literature about quantitative analysis of glazes using portable XRF should be provided. Finally, it should be specified the accuracy of these semi-quantitative analysis. I agree that it is probably good enough for the purpose of the study and mainly for comparative purposes (e.g. between the original and the replica) but this should be discussed and supported by recent literature on the topic.

Moreover, the analysed glazes are strongly irregular in thickness. This is a challenge for XRF mapping, since it was certainly not possible to properly focus the whole analysed area. This can have an impact also in the intensity of the signal from different spots and can make it difficult to say which elements are below the others, especially in the case of craters. A strong support to the interpretation of the authors comes from the study of their replica, which indeed support their interpretation of the original layer structure. However, this (the challenges posed by the irregular glaze and the solution provided by the experimental replica) should be explicitly commented in the text.

Therefore, I suggest to accept the paper for publication after these major revisions.

I report also other minor corrections or clarification requests in the following list.

• In the abstract there are sentences repeated from the introduction (lines 39-41). Rephrasing would be preferred.
• Line 58: I suggest to replace the term “majolica” with “traditional tin glaze (also known as maiolica) technique”. According to the maiolica expert Timothy Wilson (Wilson 2017, Glossary, p. 534), the spelling ‘maiolica’ is today used in English referring specifically to Italian Renaissance tin-glazed earthenware, while ‘majolica’ is currently referred to wares made by Minton and other companies in neo-Renaissance style.

(Wilson T., 2017. Italian Maiolica and Europe: Medieval, Renaissance, and Later Italian Pottery in the Ashmolean Museum, Oxford, with Some Examples Illustrating the Spread of Tin-glazed Pottery Across Europe, Ashmolean Museum of Art and Archaeology, University of Oxford.)

• 2, line 61: “X-ray fluorescence (XRF) analyses in early to mid-20th-century tile panels generally revealed silicon-rich glazes with lead and potassium as main fluxes, typically opacified with tin [8,9,13].” Since the references are all referred to the Portuguese context (if I’m not mistaken), it would be better to specify it saying “in early to mid-20th-century Portuguese tile panels”, since this could be not valid for other place of production.
  Boron was also often added in 20^th century glaze, but cannot be detected by XRF.
• 2, line 71: include reference to Figure 1a.
• 2, line 73: I would say “historically” rather than “initially”
• It would be interesting to have some additional information about the artist Ana Maria Alves Casimiro Nunes, if available.
• “The glazes were applied directly to the bisque-fired ceramic body, and the frame includes areas that feature a semi-transparent glaze with greenish hues (Figure 1b).”: how was this information on the technique acquired? Is documentation available in the Academy of Fine Arts? Or was it deduced from visual observation?
• How was the panel analysed? Were single tiles detached to fit under the XRF and Raman spectrometer? Were they sampled? Please provide more details.
• 4: there is no reference in the text to the table at the end of the page, which also does not have a number. The caption is also not complete apparently.
• 5, line 152: I suggest to rephrase as follows: “Results are presented by glaze effect, considering first crater glazes and then crazing.”
• Table 1: Please specify in the caption that the compositions are obtained by XRF. Is the composition derived from the mean of different spots or a single spot was analysed? How was the error calculated? Is it the standard deviation of the mean? Please specify.
• Line 166: replace “consider” with “was based on”
• Line 168: replace “obtained AT the original tile” with “obtained FROM the original tile”
• Line 180: replace “by μXRF at the original tile” with “by μXRF FROM the original tile.”
• 7, lines 212-214. There are also differences between the two tiles (e.g. the replica appears somewhat less glossy, at least in the picture). It would be interesting a comment by the authors about this.
• I suggest to use consistently either the term “replica” or “reproduction” to avoid confusion.
• Lines 239-242: the paragraph should be corrected taking in mind that silicon is a chemical element. Therefore, XRF shows that Si is distributed in correspondence of the grain but it’s not correct to say that the grain is made of silicon (there will be at least also oxygen, which cannot be revealed by XRF), as the authors themselves write just after. Also, the meaning of “crystalline structure of silicon” and “crystalline silicon” should be explained and commented. Is it a synthetic product (it would be interesting to comment!)? Is it an oxide? Is it quartz? The Raman spectrum in reference [17] is referred to a silicon-oxide-covered Si. In which form were these crystals intentionally added?
• Lines 260-264: Do you have any hypothesis for this inconsistency? Also, the wording of this sentence is quite confusing.
• Figure 9: please specify the scale or the magnification.

Author Response

REVIEWER 1

The paper “GLAZE EFFECTS - analytical approaches for documentation and conservation assessment of a contemporary tile panel” deals with a very interesting and original topic, promoting the attention of heritage science studies to contemporary artistic glazes.

Even if the study is focused only on one case study, the objectives and methods are well and clearly described; the use of experimental replicas is particularly suited for this type of studies and should be praised.

However, I have a few concerns about the use of XRF spectroscopy, believing that the results are not adequately commented. My main concern regards the quantification method and the interpretation of maps on such irregular samples.

Regarding the quantitative analysis, there is only a quick mention at line 127. More details should be provided (at least saying whether the internal analysis software of the instrument was used or other softwares).

Moreover, a short review of the literature about quantitative analysis of glazes using portable XRF should be provided.

Finally, it should be specified the accuracy of this semi-quantitative analysis. I agree that it is probably good enough for the purpose of the study and mainly for comparative purposes (e.g. between the original and the replica) but this should be discussed and supported by recent literature on the topic.

Moreover, the analysed glazes are strongly irregular in thickness. This is a challenge for XRF mapping, since it was certainly not possible to properly focus the whole analyzed area. This can have an impact also in the intensity of the signal from different spots and can make it difficult to say which elements are below the others, especially in the case of craters. A strong support to the interpretation of the authors comes from the study of their replica, which indeed supports their interpretation of the original layer structure. However, this (the challenges posed by the irregular glaze and the solution provided by the experimental replica) should be explicitly commented on in the text.

Therefore, I suggest accepting the paper for publication after these major revisions.

1. We thank the reviewer for the comments and sugestions. To address issues related to surface irregularities, XRF measurements were performed only on large and/or shallow crater-effect zones, which minimizes topography-related artefacts and improves focusing accuracy. All spectra were internally normalized and calibrated using the instrument’s standard procedures. Elemental maps were interpreted by selecting the flattest regions of each crater. Quantification was carried out with MQuant (fundamental parameter method), providing standardless semi-quantitative oxide concentrations appropriate for comparative analysis. For each glaze, ten points were measured to reduce standard deviation and account for micro-scale heterogeneity. We believe these clarifications fully address the reviewer’s concerns.

 

I report also other minor corrections or clarification requests in the following list.

In the abstract there are sentences repeated from the introduction (lines 39-41). Rephrasing would be preferred.

1. Introduction lines 39-41 were rephrased.

Line 58: I suggest to replace the term “majolica” with “traditional tin glaze (also known as maiolica) technique”. According to the maiolica expert Timothy Wilson (Wilson 2017, Glossary, p. 534), the spelling ‘maiolica’ is today used in English referring specifically to Italian Renaissance tin-glazed earthenware, while ‘majolica’ is currently referred to wares made by Minton and other companies in neo-Renaissance style.

(Wilson T., 2017. Italian Maiolica and Europe: Medieval, Renaissance, and Later Italian Pottery in the Ashmolean Museum, Oxford, with Some Examples Illustrating the Spread of Tin-glazed Pottery Across Europe, Ashmolean Museum of Art and Archaeology, University of Oxford.)

1. We replaced the term majolica with traditional tin glaze techniques, also known as maiolica.

2, line 61: “X-ray fluorescence (XRF) analyses in early to mid-20th-century tile panels generally revealed silicon-rich glazes with lead and potassium as main fluxes, typically opacified with tin [8,9,13].” Since the references are all referred to the Portuguese context (if I’m not mistaken), it would be better to specify it saying, “in early to mid-20th-century Portuguese tile panels”, since this could be not valid for other place of production.

Boron was also often added in 20^th century glaze but cannot be detected by XRF.

1. The correction has been made to the text in blue.
   2, line 71: include reference to Figure 1a.
2. The reference was included to the text in blue.
   2, line 73: I would say “historically” rather than “initially”
3. the substitution was made to the text in blue.

It would be interesting to have some additional information about the artist Ana Maria Alves Casimiro Nunes, if available.

1. No further information about the artist is available beyond what is stated in the text.

“The glazes were applied directly to the bisque-fired ceramic body, and the frame includes areas that feature a semi-transparent glaze with greenish hues (Figure 1b).”: how was this information on the technique acquired? Is documentation available in the Academy of Fine Arts? Or was it deduced from visual observation?

1. The information was obtained through visual observation. This is only true for the frame. The sentence was corrected “The glazes of the frame were applied directly onto the bisque-fired ceramic body. This is evident in areas where the glaze is semi-transparent, revealing the yellowish color of the ceramic body (Figure 1b).

No further information about the artwork is available beyond what is stated in the text.

How was the panel analysed? Were single tiles detached to fit under the XRF and Raman spectrometer? Were they sampled? Please provide more details.

1. The tiles from the panel, preserved individually in a box, were brought to the laboratory for observation and analysis using microscopy techniques. The examinations were car-ried out directly on the tile surfaces. This explanation was added to the text.

4, There is no reference in the text to the table at the end of the page, which also does not have a number. The caption is also not complete apparently.

1. The lost reference was added to the table along with its caption. It is a footnote table.

5, line 152: I suggest to rephrase as follows: “Results are presented by glaze effect, considering first crater glazes and then crazing.”

1. suggestion was adopted to the text.

Table 1: Please specify in the caption that the compositions are obtained by XRF. Is the composition derived from the mean of different spots or a single spot was analysed? How was the error calculated? Is it the standard deviation of the mean? Please specify.

1. Caption from Table 1 was completed. We present the mean value and standard deviation from 10 measurements from different spots.

Line 166: replace “consider” with “was based on”

1. the substitution was made to the text in blue.

Line 168: replace “obtained AT the original tile” with “obtained FROM the original tile”

1. the substitution was made to the text in blue.

Line 180: replace “by μXRF at the original tile” with “by μXRF FROM the original tile.”

1. the substitution was made to the text in blue.

7, lines 212-214. There are also differences between the two tiles (e.g. the replica appears somewhat less glossy, at least in the picture). It would be interesting a comment by the authors about this.

1. A new photograph was taken under the same light conditions and inserted in the work. These differences were not observed there.

I suggest to use consistently either the term “replica” or “reproduction” to avoid confusion.

1. We agreed to use reproduction.

Lines 239-242: the paragraph should be corrected taking in mind that silicon is a chemical element. Therefore, XRF shows that Si is distributed in correspondence of the grain but it’s not correct to say that the grain is made of silicon (there will be at least also oxygen, which cannot be revealed by XRF), as the authors themselves write just after.

1. The elemental distribution obtained by µXRF over the grains shows silicon (Si) concentrated in these areas, indicating that the grains contain this element in their composition (Figure 7).

Also, the meaning of “crystalline structure of silicon” and “crystalline silicon” should be explained and commented. Is it a synthetic product (it would be interesting to comment!)? Is it an oxide? Is it quartz? The Raman spectrum in reference [17] is referred to a silicon-oxide-covered Si. In which form were these crystals intentionally added?

1. The way they look and from their Raman spectra, it is a crystal of Silicon (Si). The main Raman band for crystalline silicon is a sharp, strong peak located at approximately 520-521 cm⁻¹ as shown in the reference. The older reference was substituted by a more adequate one obtained at the RRUFF project.

Lines 260-264: Do you have any hypothesis for this inconsistency? Also, the wording of this sentence is quite confusing.

1. We believe that this is not the original way of producing crazing effect, and we are not sure of the intention of the artist. It was probably just a consequence of the choice of materials. We have rephrased the paragraph. “The obtained composition does not correspond to the explanation commonly reported in the literature for the occurrence of crazing, which attributes it to a deficiency of silica and/or alumina needed to counterbalance the high thermal expansion of fluxes such as potassium oxide. Instead, these findings support the assumption that Si crystals were responsible for the crazing effect observed in the tiles.”

Figure 9: please specify the scale or the magnification.

1. It’s a photograph detail not a micrography.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript shows very interesting ideas such as is the O₂ which produces the crater effect instead the water vapour, as it has been published or that the crazing effect is owing to the presence of silicon rather than the lack of silica or alumina, as the references assess.

 

Those ideas are very interesting but should be supported by more data and more experiments than just one replica of the FBAUL/CER/AzC/182 tile. I suggest justifying better the new theories with more experiments, controlling other variables such as water vapour and substratum composition for explaining crater formation, or % of silica, alumina, and silicon for the crazing effect.

 

Here, more suggestions and some mistakes that I have found and, I hope, can help to improve this manuscript.

 

In general, I am quite confused with the use the term “glaze” in this manuscript. I think the authors use it as a synonymous of tile and use it meaning either substratum base, colour layer as well as the proper glaze layer. For example, see page 5, last lines.

 

Page 3, line 91: 2. Materials and Methods (639 words) delete (939 words)

 

Page 4, Micro-Raman spectroscopy. I miss data about the laser power, exposure time, and number of accumulations. These data should be included since are very relevant for avoid changes in the mineral composition because the laser can heat the sample and induce structural and compositional crystallographic changes.

 

Table in page 4, Is it complete? I miss the table caption and its citation in the main text.

Figure 3: I suggest to enlarge the photos since are too small.

 

Page 5, last lines: authors suggest there is an order of application of the layers, but why that specific order? why the first one was Zr, over it was the Co layer and afterwards the Mn? Do they already know? if so, they should include some references or explain why they know it.

 

They find Zr and Mn inside the craters, why do they suggest that only Zr was used in the in the base layer which is covered by a Co layer? What has happened with the Mn layer?

 

For giving more weight to their work, I suggest trying with different % of MnO2 and check if there

are differences regarding to the number or size of the craters (which will be new nonpublished data yet) or trying with different substrata or different % of Mn, Co, and Zr, or with different amount of water or of minerals than, when melting, produce water vapour.

 

Crazing glazes:

 

Authors assess that silicon particles are the responsible of the crazing effect in their tiles. It looks like they have found just one particle related with this effect. Please, enlarge this chapter justifying that each time there is a crazing effect is related with a silicon particle. If not, if there is only one particle related with crazing, could have been just by chance.

 

Page 8, final paragraph. Authors should explain and justify much deeper what they have found for rejecting the commonly published idea about the origin of the crazing effect. I suggest using replica tiles with different composition of silica, alumina, and silicon to be sure of their assertion. From one original tile and one replica with a similar composition than the original, there is not possible to obtain any conclusion, particularly so important as theirs. The origin of the crazing could be related with the amount of  silica and alumina, and the silicon could just be the weak point where the cracks start. Are there more cracks related with those crystals than the cracks in other areas of the tiles? Do the cracks have a radial distribution around silicon crystals? Are all those particles related with the cracks, or it depends on the silicon size? have authors tried tiles without silicon and see if there are still cracks? and why silicon is related with the cracks, because of its composition or because it does not melt? Have they proved if other non molten particles function as crazing nucleus?

 

Page 9, lines 273, 274: Raman spectroscopy does not give chemical composition but molecular (silicon, quartz, manganite, pyrolusite, linnaeite, etc. The same chemical composition could crystalize in different structures giving different minerals (with different properties) and this is what Raman spectroscopy is able to differentiate. So, correct this paragraph.

 

Author Response

REVIEWER 2

We thank you for the valuable contributions. Corrections are addressed in this section and added to the text in blue.

This manuscript shows very interesting ideas such as is the O₂ which produces the crater effect instead the water vapour, as it has been published or that the crazing effect is owing to the presence of silicon rather than the lack of silica or alumina, as the references assess.

Those ideas are very interesting but should be supported by more data and more experiments than just one replica of the FBAUL/CER/AzC/182 tile. I suggest justifying better the new theories with more experiments, controlling other variables such as water vapour and substratum composition for explaining crater formation, or % of silica, alumina, and silicon for the crazing effect.

Here, more suggestions and some mistakes that I have found and, I hope, can help to improve this manuscript. 

In general, I am quite confused with the use the term “glaze” in this manuscript. I think the authors use it as a synonymous of tile and use it meaning either substratum base, colour layer as well as the proper glaze layer. For example, see page 5, last lines.

1. The text has been revised to prevent confusion between tile and glaze.

Page 3, line 91: 2. Materials and Methods (639 words) delete (939 words)

1. Words have been deleted.

Page 4, Micro-Raman spectroscopy. I miss data about the laser power, exposure time, and number of accumulations. These data should be included since are very relevant for avoid changes in the mineral composition because the laser can heat the sample and induce structural and compositional crystallographic changes.

1. The following information was added to this section. The laser power at the sample was kept at 0.05 mW to avoid structural and compositional crystallographic changes. Accumulation times per spectrum were set to 100 s.

Table in page 4, Is it complete? I miss the table caption and its citation in the main text.

1. Table in page 4 is referenced in the text as a footnote. The caption was added to the table.

Figure 3: I suggest to enlarge the photos since are too small.

1. Figure 3 was replaced with a larger one.

Page 5, last lines: authors suggest there is an order of application of the layers, but why that specific order? why the first one was Zr, over it was the Co layer and afterwards the Mn? Do they already know? if so, they should include some references or explain why they know it. They find Zr and Mn inside the craters, why do they suggest that only Zr was used in the base layer which is covered by a Co layer? What has happened with the Mn layer?

3. These results were based on elemental distribution mapping of selected areas using µXRF spectrometry. The maps obtained from the original glaze revealed a different elemental distribution on its surface for Mn and Zr, and Co (see Figure 3). Although Mn and Zr were identified within the white cratered regions, Co was predominantly distributed around the periphery of the craters. This leads us to believe that underneath the Co blue layer, there is a Zr white one. Mn was not referred at this point because it is not responsible for the white color but for the craters as demonstrated in the following paragraph. Following this reasoning, the Mn map was removed from figure 3.

For giving more weight to their work, I suggest trying with different % of MnO2 and check if there are differences regarding to the number or size of the craters (which will be new nonpublished data yet) or trying with different substrata or different % of Mn, Co, and Zr, or with different amount of water or of minerals than, when melting, produce water vapour.

1. We appreciate your valuable suggestions. This study represents an initial exploration of glaze effects. In future work, we plan to investigate these aspects further by testing different MnO₂ concentrations, substrate types, and compositional variations to better understand their influence on crater formation.

Crazing glazes:

Authors assess that silicon particles are the responsible of the crazing effect in their tiles. It looks like they have found just one particle related with this effect. Please, enlarge this chapter justifying that each time there is a crazing effect is related with a silicon particle. If not, if there is only one particle related with crazing, could have been just by chance.

1. The section was enlarged according to reviewer suggestions.

Page 8, final paragraph. Authors should explain and justify much deeper what they have found for rejecting the commonly published idea about the origin of the crazing effect. I suggest using replica tiles with different composition of silica, alumina, and silicon to be sure of their assertion. From one original tile and one replica with a similar composition than the original, there is not possible to obtain any conclusion, particularly so important as theirs. The origin of the crazing could be related with the amount of  silica and alumina, and the silicon could just be the weak point where the cracks start. Are there more cracks related with those crystals than the cracks in other areas of the tiles? Do the cracks have a radial distribution around silicon crystals? Are all those particles related with the cracks, or it depends on the silicon size? have authors tried tiles without silicon and see if there are still cracks? and why silicon is related with the cracks, because of its composition or because it does not melt? Have they proved if other non molten particles function as crazing nucleus?

1. We believe that this is not the original way of producing crazing effect, and we are not sure of the intention of the artist. It was probably just a consequence of the choice of materials. Cracks have radial distribution as can be observed and they originate in different sizes silicon crystals. As the melting point of crystalline silicon (~1400 °C) is significantly higher than the firing temperature of the glaze (~900 °C) they do not melt and exhibit minimal interaction with the vitreous matrix and its network modifiers. As a result, they act as stress concentrators within the glaze, leading to cracking and structural weakening of the overlying glaze layer. (see image in attached file)

 Page 9, lines 273, 274: Raman spectroscopy does not give chemical composition but molecular (silicon, quartz, manganite, pyrolusite, linnaeite, etc. The same chemical composition could crystalize in different structures giving different minerals (with different properties) and this is what Raman spectroscopy is able to differentiate. So, correct this paragraph.

1. The paragraph was corrected according to reviewer’s suggestion

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

The presented topic is quite interesting, but you should improve the scientific quality of the manuscript. Next to the XRF data, I suggest adding more Raman data, as these could help in better understanding firing conditions and application of glaze. A cross-section (if available) could further support your experimental tiles. I suggest better describing the methodology used for the tile reconstruction, adding actual pictures of the steps. I think improving the references is also important in referring to international publications.

The topic is definitely of interest, but the comparison made is limited. You should add additional data to support the outcome, with a comparison with the literature.

Regards

Comments for author File: Comments.pdf

Author Response

REVIEWER 3

 

Dear Authors,

The presented topic is quite interesting, but you should improve the scientific quality of the manuscript. Next to the XRF data, I suggest adding more Raman data, as these could help in better understanding firing conditions and application of glaze.

A cross-section (if available) could further support your experimental tiles.

I suggest better describing the methodology used for the tile reconstruction, adding actual pictures of the steps.

I think improving the references is also important in referring to international publications.

The topic is definitely of interest, but the comparison made is limited. You should add additional data to support the outcome, with a comparison with the literature.

Regards

1. We sincerely thank the reviewer for the constructive suggestions. This study represents an initial exploration of glaze effects. In future work, we plan to expand the analytical dataset by incorporating additional Raman measurements, which will enhance understanding of firing conditions and glaze application processes. Unfortunately, we were not permitted to obtain cross-sections or remove samples from the original tiles.

A detailed schematic illustrating the reconstruction methodology is already provided in the manuscript, which we believe adequately conveys the procedure. Step-by-step photographs are not available; however, the description and schematic together provide sufficient clarity for the reader.

To the best of our knowledge, no previous analytical studies on effect glazes exist for direct comparison, which is why this study focuses on establishing an initial dataset. We have also revised the references to include relevant international publications where possible.

 

2.1 The tile panel

you should give more details regarding the conservation status and history: where are the tiles located (indoor-outdoor), did the tiles have in the past conservation treatment? do you have any connection with the artist or are there any indication by the artist?

2. Our attempts to contact the artist were unsuccessful. No further information about the artwork or the artist is available beyond what is stated in the text. The tiles are stored in a box in the ceramic painting storage area of the faculty. Although the glaze on the frame of the tile panel shows structural instability, evidenced by an extensive network of crazing that has led to partial detachment of the glaze, there is no record of any previous conservation intervention. This information was added in blue to the manuscript section 2.1 the tile panel.

2.3 Micro-X-ray fluorescence spectrometry (μXRF) analysis

did you perform any calibration with standard materials in order to occur for possible element contribution?

1. Quantitative evaluation of the glazes was carried out using the internal software MQuant, which is based on the fundamental parameter method and enables standard-less quantification of sample oxides, considering those typically present in glazes.

This information was added to the text.

How many samples or point analysis did you perform per area?

1. Analyses were performed directly on the tiles at 10 measurement points

2.4 Micro-Raman spectroscopy (μRaman)

analysis how may point per sample did you consider? did you do any other mathematical correction next to deconvolution (baseline, normalization?)

1. We analyzed a total of 10 grains. Baseline correction was not needed since the spectra present no background.

2.5 Experimental reproductions

could you please give more details on sample make-up did you apply the glass as powder or was it in semimelted and then cooked?

2. The glaze was applied as an aqueous suspension prepared from finely ground glaze powder to ensure uniform distribution over the surface. The information on the make-up was integrated in section 2.5 Experimental reproductions.
3. Results and Discussion

did you have the possibility to collect samples and made a cross section? this will help in supporting the hypothesis of layer application.

1. We were not allowed to obtain cross-sections or remove samples from the original tiles.

coudl you expaline why you indicate different precision according to oxide?

1. The different numerical precision for individual oxides reflects their respective concentration levels and the analytical precision of XRF measurements. Major elements yield higher counting statistics and lower relative uncertainty, so they are reported with one or zero decimal places, while minor oxides are shown with two decimals to represent the appropriate significant figures.

The analytical precision of each oxide is also influenced by the detector’s energy-dependent sensitivity. XRF detectors do not respond uniformly across the X-ray energy spectrum: their efficiency decreases for both very low- and very high-energy fluorescence lines. As a result, elements with low-energy emissions (e.g., Na, Al, Si) tend to exhibit higher measurement uncertainty than those with mid-energy lines (e.g., Ca, K, Fe, Zn). The reported decimal precision for each oxide therefore reflects not only its concentration level but also the intrinsic detection efficiency of its characteristic X-ray energy.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I acknowledge that all the revisions were made. 
I just highlight that the scales in Figure 10 are too small to be read.

Reviewer 2 Report

Comments and Suggestions for Authors

I would like the authors just to check if the Raman laser power used was 0,05 mW o 0,5 mW. I have used different instrument and I have never seen 0,05 mW but could be!

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

thanks for the revised version of the manuscript and for taking into consideration the comments 

Regards