Reproduction and Testing of Display Options for the Slide-Based Artwork Slides de Cavalete (1978–1979) by Ângelo de Sousa: An Experimental Study

Round 1

Reviewer 1 Report

The manuscript by Silva and Urze concerns the reproduction and the testing of display options of a slide-based artwork realized at the end of the 70’s. The topic is relevant for the journal and I really enjoyed the manuscript. It reads well and I’d just like to suggest a couple of very minor changes that would increase the readability of the work.

While preparing the corrected version of the manuscript, please consider the following:

- The title would better reflect the content (and make it even more appealing) if you change it to “Reproduction and testing of display options of …”

- the word “experimental” in the title of section 3 is not necessary, please just leave “Reproducing Slides de cavalete”.

- pay attention to figure 8, that in this version is not completely visible.

- to better reflect and illustrate the content, please change the title of section 5.2 to “Display testing at …”.

- Figure 9, 10 and 11 are difficult to be read, not only because of the resolution but also due to the character dimension. Please increase it and/or change the format.

Author Response

A1.1: Based on the reviewer suggestion, the title was changed to “Reproduction and testing of display options for the slide-based artwork Slides de cavalete (1978-1979) by Ângelo de Sousa: an experimental study”

A1.2: ‘Reproducing Slides de cavalete’ and ‘Exhibition at FCT NOVA’ are sub-sections of the main section ‘3. Experimental’, and were therefore changed to ‘3.1. Reproducing Slides de Cavalete’ and ‘3.2. Exhibition at FCT NOVA’.

A1.3: We thank the reviewer for pointing it. This issue was corrected.

A1.4: The title of section 5.2 was changed to ‘Display testing at FCT NOVA’, as suggested.

A1.5: We thank the reviewer's suggestion, the dimension of the characters in the figures were increased to allow for a better reading.

Author Response File: Author Response.docx

Reviewer 2 Report

The article “Experimental study: testing display options for the slide-based artwork slides de cavalete (1978-1979) by Ângelo de Sousa” is focused on the study of a slide-based artwork from the Portuguese artist Ângelo de Sousa. The authors compared two different exposition scenarios and asked the visitors to fill a questionnaire to study their preferences. I find particularly interesting the idea of studying the realization process of the artwork, involving conservation students and unveiling the artist’s work through multiple attempts of recreating his technique. I would like to compliment the authors and the students who worked with them for their efforts. However, I have some doubts about the way the whole work is presented.

The abstract starts with “Slides de cavalete | Easel slides (1978-1979) is a slide-based artwork by the Portuguese artist Ângelo de Sousa (1938-2011), composed of one-hundred colour slides made with the additive synthesis of colours.”

I find this sentence hard to understand, clearly the artwork itself is not made with the additive synthesis of colours (at least not literally) and neither the colour slides. I think this sentence could be re-phrased to be more understandable.

From the abstract I understand that the visitors preferred the original exposition conditions designed by the artist rather than the modern ones, consisting of a digital projection. I find quite understandable that the visitors valued more positively the expositive approach designed by the artist, but my question is: why was the artwork exposed in different conditions in the first place?

The introduction is confusing, the authors mention conservation issues but vaguely. What conservation issues did the authors address studying this specific artwork?

I find interesting the sentence “Colour slides are chromogenic reversal films, which are chemically unstable photographic materials” (lines 48-49). Did you perform any chemical analysis in order to characterize the materials or this is just a general notion on photographic materials?

Durability of photographic heritage is usually strongly connected to the chemical nature of the materials used, and its lifespan can vary greatly. Why are your materials unstable? Is it only because of the extreme conditions caused by the projection, or have you detected other chemical or physical causes? Were the conservation conditions the reason why the artwork was not exposed following the artist’s guidelines?

I would also add a definition for “chromogenic reversal film” since I think not all the readers have experience with these materials.

The introduction provides some interesting insights on the challenges of digital conservation; however, reading the introduction I struggle to understand the purpose of this study.

Lines 97-98 “Display options for the slide-based artwork Slides de cavalete | Easel slides (1978-1979) by the Portuguese artist Ângelo de Sousa (1938-2011) were weighted and are presented in this paper”. I wonder, why? What was the purpose of this study? The authors themselves affirm that “Ângelo 98 de Sousa is a Portuguese contemporary artist, known for an experimentalism that enabled him to achieve exceptional originality” (lines 99-100). I absolutely agree that de Sousa was an incredibly talented artist, why you could not just respect his wishes and display his artwork following his instructions? I understand that the choice of exposing the digitized artwork was made in order to preserve the original piece, but I think the authors could explain more in detail this choice, also offering some details on how the expositive conditions (light/heat) can harm the photographic materials. Without this information it seems that the exposition choices were only driven by personal taste. 

Furthermore, the authors affirm how “It should be stressed out that, contrarily to Ângelo de

Sousa who worked alone (as far as it is known), the reproduced images were obtained with the participation of several students managing the different tasks implied in the process (shooting, changing filters, changing masks, applying secondary masks to produce light gradations, etc.)” (lines 287-290). From this part I understand that an important part of the experimental study was carried out by conservation students, did the authors participate actively in this part or only supervised? Are the students who collaborated to this study acknowledged or better, listed as authors?

Figure 11 is pretty self-explanatory, thus I find the lines 388-408 redundant, since in this part the authors seem to repeat the same concepts expressed by the figure.

The whole article could be revised to be more concise and hence more easily accessible and readable.

Author Response

A2.1: We thank the reviewer for her very helpful and pertinent comments to the work and abstract. We have completely rewritten the summary to clarify the scope of our work and the description of the time-based media studied.

The mentioned sentence was re-phrased, as follows: “Slides de cavalete | Easel slides (1978-1979) is a slide-based artwork by the Portuguese artist Ângelo de Sousa (1938-2011), composed of one-hundred colour slides. Each image was produced using different proportions of red, green and blue (RGB) lights to obtain colour gradations.” (lines 17-18).

A2.2: The reviewer is right to point out this problem, as it was not clear in our work. We hope that the new version of the abstract has made this aspect clearer

During the investigation conducted within the framework of this study, it was discovered that the artwork was first presented using a slide projection, projected over a canvas mounted in an easel, based on a letter written by the artist and addressed to Fundação Calouste Gulbenkian – FCG. The abstract and introduction were slightly modified to make it clearer that the display setup first used by the artist was recently discovered during the present investigation. After the artist’s death, the work started to be presented using different display setups (section 1.2., lines 124-152). In the last 2 exhibitions, carried out in 2017, the work was presented using a digital projection in the museums’ wall, according to curatorial choices. Updating the original display equipment for digital technology is tempting for museums/exhibition organizers, because it (apparently) streamlines the exhibition of the works and reduces the costs and maintenance associated with slide exhibition copies. Although for us it seems obvious that the artwork should be projected using a slide projector and the display instructions left by the artist, based on the contact we add with curators during the present study, we understood it is not at all straightforward. Apart from that, it is possible that curators were not aware of the display setup defined by the artist. Independently of that, curators might prefer to shift the original display technology to digital, for commodity, costs saving, or for other reasons. That is why we decided to gather evidence on what are the consequences of shifting the original technology to digital technology.

A2.3: The introduction was reorganized to become clearer. It is now composed of section ‘1.1. Challenges of exhibiting slide-based artworks’ and ‘1.2. Case study: Slides de cavalete | Easel slides by Ângelo de Sousa’. Section 1.1. exposes the issues related with the preservation and exhibition of slide-based artworks in general. Section 1.2. presents the artwork under study, its concept and display history.

While studying this work, we addressed the typical issues arising from the preservation and exhibition of slide-based artworks: how to display a work which is dependent on technology to be presented and in which the original images cannot be projected; should the original technology (slide projection) be maintained in this case, or can it be shifted to digital technology; what is loss with this transition; is the significance of the artwork affected or not?

A2.4: Chromogenic reversal films are intrinsically unstable photographic materials. Upon time, this type of products has been improved. Nevertheless, under uncontrolled temperature and relative humidity, as well as light, all chromogenic dyes fade shifting the original colour balance of the image, within a short timeframe. It is now generally accepted that colour slides cannot be displayed due to the aggressive condition to which they would be subjected to (after only a few days/weeks, depending on the type of film, discernible changes occur). That is why the original Slides de Cavalete could never be projected today.

We rephrased the sentence and the following ones, to be clearer and added some references: “Colour slides are chromogenic reversal films, photographic materials composed of a polymer support (e.g. cellulose triacetate) and at least three superimposed emulsion layers made of cyan, magenta and yellow dyes, respectively, dispersed in a proteinaceous matrix (gelatine) [3]. These are chemically unstable photographic materials, highly prone to fade under uncontrolled environmental conditions and/or when exposed to light. Over time, the different dyes fade at different rates causing a shifting in the original colour balance [3-8]”. (lines 55-61)

A2.5: We understand the point raised by the reviewer and hope to have explained it correctly in the revised version, as well as in the completely rewritten abstract. Please see also our answer in 2.2.

The sentence was moved to the introduction (see line 106-108).

Section 1.2. explains why we decided to test the variability of the work projected with a slide projector and digital projector (line 161-169). Since the original slides cannot be displayed, there is necessarily a migration step in order to allow the presentation of the work. During this process, the original technology can be reproduced or shifted to other technology (as it has already been). Taking in consideration the display history of the work (and the facility of shifting the original technology to digital technology nowadays), we considered relevant to undertake this study in order to compare the work projected with a slide projector and a digital projector and understand what is lost (or not) by changing the original technology.

A2.6: The investigation and first testings were carried out by the authors of this paper, within the framework of the PhD of the first author. After gathering the ground knowledge necessary to reproduce the work, several experiences and specific reproductions of slides were carried out (following the directions and under the supervision of the authors), in the context of some conservation courses.

A2.7: We believe that it will be important to keep the text that provides a description of the main points of the results form the questionnaire depicted in Figure 11.

A2.8: Following the points raised by the reviewer and her suggestions, the abstract was fully rewritten and the article extensively revised. In particular, repetitions have been excluded to provide a more concise text. In addition, some footnotes have been removed.

Author Response File: Author Response.docx

Reviewer 3 Report

The article is not adequately referenced. The title "references" is number 1, so, they have to review the number of all references.

The discussion is coherent and balanced but it may be improved adding references.

Author Response

A3.1: We thank the reviewer for pointing this error, which was corrected.

A3.2: The paper was reviewed, and some references were added.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The revised version of the article is clearer and improved. The work is interesting and well written, and I would like to compliment the authors for their work.