Insights into Della Robbia’s Terracotta Monument to Cardinal Federighi: Raw Materials and Technologies

Round 1

Reviewer 1 Report

Please see the attached file with my suggestions.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer 1, authors are grateful for your valuable comments and suggestions. We profited of your
remarks to improve our text. A new version of the manuscript highlighting by track changes the
modifications done in the text was uploaded. Authors would like to better explain few aspects following
your valuable suggestions.
Most of the points raised seem to us extremely correct and have therefore met with appropriate changes,
increasing the quality of the text. Others, however, cannot be reached.
In the attached report, we specify modifications accomplished following your suggestions point by point

Author Response File: Author Response.pdf

Reviewer 2 Report

The topic of the paper is the material analysis of a glazed and gilded della Robbia terracotta monument. The topic is interesting, the raw materials used and the manufacturing technology of the object are worth studying in detail. However, I suggest some improvements in the manuscript. My most important comment is that if the authors have cross sections of differently coloured glazes which were examined by SEM-EDS, it is unclear why a more detailed characterization of glazes is not presented, especially the chemical composition of the glazes is missing. Additionally, the results are not compared in detail to the result of former studies performed on other della Robbia objects.

 

Abstract:

• multimodal analytical strategy -> multi-analytical strategy
• „…their background is gilded, not applied to the surface as in previous glazed works of della Robbia, but instead incorporated inside the glaze” – according to the SEM images, the gilding covers the glaze, and it is not inside the glaze

Introduction:

• “third firing” technique – explain what it means or refer to the relevant part of the manuscript where it is explained
• other glazed terracotta works of della Robbia with cold-gilding is mentioned, for which some examples would be useful; are there any analytical data for comparison?

Materials and methods:

• FTIR analysis is indicated in Table 2, but no results are presented, similarly, XRD of mortars is mentioned, but not presented either; if you do not want to present these results, it is better to delete them from Table 2
• did you sample green and purple glazes?

Results:

• FORS showed bands due to Fe3+ in iron oxides (hematite, maghemite, goethite...) in greyish glaze -> any figure for this?
• FORS of yellow glazes: delete oxides (only lead, antimony and iron) from the text
• blue glaze: distribution of the tin oxide particles seems to be not uniform in fact; type of grey inclusions in the BSE images (Fig. 4) is not indicated (probably wollastonite as mentioned later), did you detect any residues of the cobalt-bearing pigment? a stereomicroscopic image of the blue glaze should be added
• yellow/orange glaze underneath the gilding: how do you explain the absence of Sb and presence of Fe, Ni and Zn elements in the XRF spectrum (Fig. 5)? if you expect lead antimonate pigment, the peaks related to antimony must be present; the microtexture and composition of these glazes are not presented
• gilding: please refer to Fig. 7; from the BSE images the embedding of the gold layer into the glaze is not seen, only its adherence to the glaze
• glazes composition: glazes were classified into three types, however, description of the groups is very short and should be extended, e.g., the colour and the chemical composition of the analysed glazes are not indicated; stereomicroscopic images next to the BSE images would be very useful; group 1: what colour is the lower glaze? is the upper glaze a coperta (transparent lead glaze)? groups 2 & 3: which glazes/samples belong to these groups?
• formation of Ca-silicate is not discussed, especially regarding group 2 glazes, in which wollastonite is abundantly present throughout the glaze
• how do you explain the application of different glazes (one-layer and two-layer glazes) on the monument? how typical was to use two-layer glaze (coperta) on della Robbia objects? are there examples for this?
• terracotta body: SEM-EDS analysis of the ceramic body is mentioned, but no data are presented; additionally, some BSE images should be added as the microtexture of the body is important, for example to visually present the form and amount of calcite as its presence was detected by XRD together with newly-formed silicate phases; some elements (Na, K, Mg) is missing from Table 4 (but mentioned as components detected by SEM-EDS)
• the CaO content is remarkably higher (30-35 wt%) in the ceramic body than in other della Robbia bodies (typically a calcareous clay with 20 to 25 wt% CaO content was used by the workshop, and the quality of the clay used was consistent during della Robbia generations, as demonstrated by former studies); how do you explain the higher CaO content of the clay used?

 

A language editing and check for typos is highly recommended. For example: Enamel -> glaze; FORS-XRF is correctly FORS, XRF; metods -> methods; in Table 2 “and” instead of “e”; cupper -> copper; in Table 2 “inductively-coupled” instead of “ion coupled”; caption of Fig. 3: blue glazes instead of blue glazed; cleraly -> clearly; calculated by ICP-MS -> measured by ICP-MS; cacite > calcite

Literature should be referred correctly in the text: e.g. [5] [14] is correctly [5-14]; [1] [4] is [1-4]?; [17]-[22] is [17-22]; [24] [26] is [24-26];

Check that all listed references are cited in the text.

Author Response

Dear Reviewer 2, authors are grateful for your valuable comments and suggestions. We profited of your
remarks to improve our text. A new version of the manuscript highlighting by track changes the
modifications done in the text was uploaded. Authors would like to better explain few aspects following
your valuable suggestions.
Allof the points raised seem to us extremely correct and have therefore met with appropriate changes,
increasing the quality of the text.
in the attached report, we specify modifications accomplished following the referee suggestions point by point

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I have no suggestions

Author Response

Authors would like to thank reviewer for the previous suggestions which implemented our manuscript

Reviewer 2 Report

Regarding the authors’ reply:

 

Thank you for your answer and corrections, I confirm that the paper improved significantly.

 

Although, I am very sorry that you did not sample all the glazes, only the blue. It would have been interesting to study all of them in detail. I expected this detailed study as you promised that “the present study focuses first to examine and characterise the raw materials and the procedure to realise the glazed tiles” in the ‘Introduction’. Additionally, you wrote in the ’Materials and methods’ that “Micro-fragments were collected to characterize the composition and the executive technique of gilding, glazes and terracotta bodies”.

 

One comment: “Tite 2009 reports the use of this “coperta” in della Robbia workshop masterpiece “The use of calcareous clay bodies and lead-alkali glazes, the variable tin oxide content of the glaze, the addition of sand to the opaque glazes, and the final application of a transparent coperta glaze with a lower viscosity than the underlying opaque glaze can, in general, be explained in terms of ease of production and the quality of the final product.”.” - I do not agree; this sentence is not for della Robbia objects, but for maiolica in general.

 

Regarding the revised text:

 

Some minor corrections are still needed.

 

Introduction: „…but any archaeometric study was previously performed on the artist’s production, characterised by this sperimental technique.” -> correctly: no archaeometric study… experimental technique; which technique do you mean here?, gilding? please specify

 

Materials and methods:

- “The XRPD analyses were performed on the terracotta samples and on the mortars” – please add that XRD results of the mortars (more precisely stucco and concrete according to Table 2) are not discussed in this paper

- please indicate the analytical conditions for the chemical analysis of the glaze (area or point analysis?, acquisition time?, number of measurements? etc.)

 

Results:

Coloured glazes: yellow glaze: iron oxides -> only iron, delete oxide

 

Figure 7 is still not referred to in the text.

 

3.3. Glazes composition -> this is valid only for the gilded areas if understand correctly, as you did not sample other (coloured) glazes expect the blue, so correct this heading to make it clear for the reader

 

“The interfaces, in general, as compared to the average glaze composition, are richer in Al, K, Ca and Si and Si.” -> some words are duplicate in my version, please delete

 

Table 3: delete the third decimal for Na2O (1.91 wt%)

 

Terracotta body: I suggest to include the SEM-BSE image of the terracotta body as a new figure.

 

Author Response

Dear reviewer we profited of your comments to imrove our text. Comments are in the file attached.

Author Response File: Author Response.pdf