University of Glasgow
History of Art
Honours Dissertation
March 2017
The Future of Remedial Painting Conservation
in the Public Sector of the UK:
Learning from Italy and Applying New Technology in the
Form of 3D Scanning and Printing.
Madeleine Frances White
2070881
Word Length: 11,931
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Acknowledgements
Writing this dissertation would not have been possible without the following people who provided invaluable support:
• Mark Richter, my dissertation supervisor who kindly provided help and guidance
throughout this project.
• Aileen Nisbet, Jacqueline Ridge, Suzanne Ross, Polly Smith and Chris Miller for their
generosity in finding the time in their busy schedules to talk with me.
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Contents
Title page p. 1.
Acknowledgements p. 2.
Contents p. 3.
Image Index p. 5.
Abstract p. 15.
Introduction p. 16.
Chapter 1: Support Strengthening p. 18.
o Minimal Intervention p. 18.
o The Greenwich Conference p. 21.
o An Italian Approach p. 22.
o Similarities to the UK’s Approach p. 23.
o Looking Towards the Future of Support Strengthening p. 25.
Chapter 2: Cleaning p. 27.
o The UK’s Approach to Cleaning p. 27.
o Italy’s Approach to Cleaning p. 28.
o The Cleaning of The Last Supper p. 29.
o Looking Towards the Future of Cleaning p. 31.
Chapter 3: Retouching p. 32.
o Changing Attitudes Surrounding Conservation p. 33.
o Deceptive Restoration p. 35.
o Visible Restoration p. 37.
o Looking Towards the Future of Retouching p. 40.
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Chapter 4: The Future of Conservation p. 42.
o 3D Scanning p. 43.
o 3D Printing p. 45.
Conclusion p. 48.
Bibliography p. 50.
Appendix p. 58.
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Image Index
Figure 1: Image A: Cimabue, Crucifixion, 1280s, tempera on wood, 3.36 x 2.67 m, Museo di Santa Croce, Florence, pictured before the flood. Sourced from Umberto Baldini and Ornella Casazza, The Cimabue Crucifix, (Florence: Olivetti, 1982) p. 83.
Image B: Cimabue, Crucifixion, 1280s, tempera on wood, 3.36 x 2.67 m, Museo di Santa Croce, Florence, after the flood, before restoration, detail. Sourced from Umberto Baldini and Ornella Casazza, The Cimabue Crucifix, (Florence: Olivetti, 1982) p. 104.
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Image C: Cimabue, Crucifixion, 1280s, tempera on wood, 3.36 x 2.67 m, Museo di Santa Croce, after restoration. Sourced from Umberto Baldini and Ornella Casazza, The Cimabue Crucifix, (Florence: Olivetti, 1982) p. 115.
Images D & E: Cimabue, Crucifixion, 1280s, tempera on wood, 3.36 x 2.67 m, Museo di Santa Croce, after restoration, details. Sourced from Umberto Baldini and Ornella Casazza, The Cimabue Crucifix, (Florence: Olivetti, 1982) pp. 117 – 118.
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Figure 2: Image A: Isaac Messina, Re-restoration of Cimabue’s Crucifixion, after Cimabue, c. 2014, tempera on panel, dimensions unknown, Messina’s private collection, after panel preparation. Sourced from Isaac Messina, “A New Approach to the Restoration of Cimabue’s Santa Croce Crucifix”, (BA diss., Syracuse University, 2014).
Image B: Isaac Messina, Re-restoration of Cimabue’s Crucifixion, after Cimabue, c. 2014, tempera on panel, dimensions unknown, Messina’s private collection, detail in progress. Sourced from Isaac Messina, “A New Approach to the Restoration of Cimabue’s Santa Croce Crucifix”, (BA diss., Syracuse University, 2014).
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Image C: Isaac Messina, Re-restoration of Cimabue’s Crucifixion, after Cimabue, c. 2014, tempera on panel, dimensions unknown, Messina’s private collection, finished panel. Sourced from Isaac Messina, “A New Approach to the Restoration of Cimabue’s Santa Croce Crucifix”, (BA diss., Syracuse University, 2014).
Images D & E: Isaac Messina, Re-restoration of Cimabue’s Crucifixion, after Cimabue, c. 2014, tempera on panel, dimensions unknown, Messina’s private collection, details from finished panel. Sourced from Isaac Messina, “A New Approach to the Restoration of Cimabue’s Santa Croce Crucifix”, (BA diss., Syracuse University, 2014).
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Figure 3: Image A: Leonardo da Vinci, The Last Supper, c. 1495 - 97/98, tempera and oil on plaster, 4.6 x 8.8 m, Refectory of S. Maria delle Grazie, Milan, the figure of Christ much altered by previous restorations, the same during the cleaning process, the same after the completion of the restoration. Sourced from Brambilla Barcilon, Pinin, and Pietro C. Marani. Leonardo: The Last Supper (Figure 6). (Chicago: University of Chicago Press, 2001) p. 355.
Image B: Leonardo da Vinci, The Last Supper, c. 1495 - 97/98, tempera and oil on plaster, 4.6 x 8.8 m, Refectory of S. Maria delle Grazie, Milan, after restoration. Sourced from Brambilla Barcilon, Pinin, and Pietro C. Marani. Leonardo: The Last Supper (Figure 6). (Chicago: University of Chicago Press, 2001) pp. 152.
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Figure 4: Image A: Giovanni Battista Cima da Conegliano, The Incredulity of Saint Thomas, aprox. c. 1503-4, oil on synthetic panel, transferred from poplar, 2.94 x 1.99 m, National Gallery, London, after restoration. Sourced from The National Gallery, The Incredulity of Saint Thomas, https://www.nationalgallery.org.uk/paintings/giovanni-battista-cima-da-conegliano-the-incredulity-of-saint- thomas, [Accessed: 08/03/2017].
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Image B & (detail) C: Giovanni Battista Cima da Conegliano, The Incredulity of Saint Thomas, aprox. c. 1503-4, oil on synthetic panel, transferred from poplar, 2.94 x 1.99 m, National Gallery, London, after cleaning, before restoration, with detail. • Image sourced from Jill Dunkerton and Ashok Roy, “The Technique and Restoration of Cima’s ‘The Incredulity of S. Thomas’”, National Gallery Technical Bulletin, vol. 10, (1986): 59. • Detail sourced from David Bomford, with Jill Dunkerton and Martin Wyld, A Closer Look: Conservation of Paintings, (London: National Gallery Limited, 2009). p. 76.
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Figure 5: Camille Pissarro, Fox Hill, c. 1870, oil on canvas, 35 x 46 cm, National Gallery, London. Sourced from The National Gallery, Fox Hill, Upper Norwood, https://www.nationalgallery.org.uk/paintings/camille-pissarro- fox-hill-upper-norwood, [Accessed: 08/03/2017].
Figure 6: Image A: Master of the Story of Griselda, The Story of Griselda, Part I: Marriage, c. 1494, oil and tempera on wood, 61.6 x 154.3 cm, National Gallery, London. Sourced from David Bomford, with Jill Dunkerton and Martin Wyld, A Closer Look: Conservation of Paintings, (London: National Gallery Limited, 2009). p. 66.
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Image B: Master of the Story of Griselda, The Story of Griselda, Part I: Marriage, c. 1494, oil and tempera on wood, 61.6 x 154.3 cm, National Gallery, London, detail before restoration. Sourced from David Bomford, with Jill Dunkerton and Martin Wyld, A Closer Look: Conservation of Paintings, (London: National Gallery Limited, 2009). p. 66.
Image C: Master of the Story of Griselda, The Story of Griselda, Part I: Marriage, c. 1494, oil and tempera on wood, 61.6 x 154.3 cm, National Gallery, London, detail after restoration. Sourced from David Bomford, with Jill Dunkerton and Martin Wyld, A Closer Look: Conservation of Paintings, (London: National Gallery Limited, 2009) p. 67.
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Figure 7: Mark Rothko, The Harvard Triptych Murals, c. 1962, oil on canvas, Distemper, egg tempera, and acrylic copolymer on canvas, 2.67 x 2.99 cm, 2.67 x 4.59 cm, 2.67 x 2.44 cm, Harvard University, Harvard. Sourced from Harvard Art Museums, Mark Rothko's Harvard Murals, http://www.harvardartmuseums.org/visit/exhibitions/4768/mark-rothkos-harvard-murals, [Accessed: 08/03/2017].
Figure 8: Leonardo da Vinci, Mona Lisa, c. 1503-16, oil on panel, 77 x 53 cm, Musée du Louvre, Paris. Sourced from BBC, The Mona Lisa (La Gioconda), http://www.bbc.co.uk/science/leonardo/gallery/monalisa.shtml, [Accessed: 08/03/2017].
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Abstract
This thesis will examine the remedial conservation methods seen in both Italy and the
United Kingdom (UK). Through the examination of the remedial conservation seen in the Italian conservation methods implemented in the restoration of Cimabue's Crucifixion (figure 1) and
Leonardo da Vinci's The Last Supper (figure 3) and parallel British conservation efforts as seen in
Giovanni Battista Cima da Conegliano’s The Incredulity of Saint Thomas (figure 4), one can reflect upon the similarities and differences in the UK’s and Italy's approach to conservation. The approach towards the strengthening of a painting’s support through applying the attitude of minimal intervention is seen in both Italy and the UK, thus with this consensus, this minimalist approach to support strengthening should be upheld in the UK to avoid unnecessary alterations to the foundations of a painting. However, disparities in the approach to restoration between the UK and
Italy are seen in the cleaning and retouching of paintings. Considering these conflicting approaches, I propound that the UK maintains its approach to the cleaning of paintings and the removal of non-original additions, whilst adopting the technique of chromatic abstraction seen in
Italian retouching. I further suggest that the UK looks toward how 3D scanning and printing might help this practice through increased accuracy, true reversibility through programming and the reduction of human error.
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Introduction
In this thesis, I will examine three main aspects of remedial conservation:1 cleaning, support strengthening and retouching. I will argue that the current methods of minimalist support strengthening and the removal of all non-original paint layers and dirty varnishes seen in the United
Kingdom (UK) are advantageous to the artwork. However, the process of retouching could be improved so as to distinguish the hand of the artist from the hand of the conservator through the use of visible restoration2 in the areas of lacunae3. This thesis will argue that the current practice of deceptive retouching4 in the UK is detrimental to the artwork as it hides the original amongst the hand of the conservator. I advocate that the process of visible restoration used in Italian conservation is preferable due to allowing for a cohesion of composition maintained through methods such as chromatic abstraction,5 whilst differentiating the original from later interventions.
This method of visible retouching well as also providing the viewer with an honest depiction of the work’s condition, as opposed to deceiving them through extensive inpainting.6
I will be focusing on the public sector of conservation because I see it as a duty of museums and galleries to be honest with the public and communicate the history of works of art without any interventive guesswork on the part of the conservator. Moreover, the private sector would be far
1 Also referred to as restoration, remedial conservation is intervention (in this case into a painting) which is not merely preventative, but seeks to restore or repair a work, whether that is structurally, aesthetically or re-exposing its originality. 2 Visible restoration is remedial conservation which seeks to distinguish itself visually from the original. 3 Lacunae is a gap or missing part, in this case a missing area of paint. 4 Deceptive retouching is remedial conservation which seeks to integrate itself seamlessly into the original so a complete level of visual unity is kept without distractions. 5 ‘The technique of chromatic abstraction is used when the loss is significant and the reintegration cannot be executed without invention or without overpowering the original. The hatched brushstrokes of pure colour are built up into a network that is described as an ‘abstraction of the original material’. The goal is to reduce the visual prominence of the loss in a way that neither competes with the original painting nor denies the damage – which is considered to be an incontrovertible aspect of the work’s history. The abstraction is intended to serve as a ‘neutral link’ between the passages of original paint.’ Kim Muir, Remembering the Past: The Role of Social Memory in the Restoration of Damaged Paintings, http://www.icom-cc.org/54/document/remembering-the-past-the-role-of-social-memory-in-the-restoration-of-damaged- paintings/?action=Site_Downloads_Downloadfile&id=776, [Accessed: 05/03/2017]. 6 Inpainting refers to paint applied to areas of lacunae which aim to re-establish the aesthetic cohesion of the work. 16 more difficult to control due to work of art being the property of their owner. However, what is prioritised in the public sector will inevitably filter into the private sector if owners of art wish to sell the works in their collection.
I will concentrate upon two important Italian conservation case studies: Cimabue’s
Crucifixion (figure 1) and Leonardo de Vinci’s The Last Supper (figure 3) and examine the similarities and differences in Italian conservation practices relative to those used in the UK comparing the latter two case studies to one seen in British conservation: Giovanni Battista Cima da
Conegliano’s The Incredulity of Saint Thomas (figure 4). I have chosen this painting due to its similarities with the two Italian paintings; it is a religious painting, which is significant due to its function as a devotional piece, meaning that a level of readability and cohesion is imperative
(although, unlike da Vinci’s and Cimabue’s, it is no longer in use and now resides in the National
Gallery). Furthermore, it is Italian in origin, thus the style and genre is in line with that of da
Vinci’s and Cimabue’s. Therefore, this provides comparable cases in which to evaluate the similarities and differences in remedial conservation treatment between Italy and the UK in order to analyse the most favourable methods to propose for the future of conservation in the UK.
I will examine how new technology in the form of three dimensional (3D) scanning and 3D printing might help aid such conservation efforts through accuracy, reversibility7 and a reduction of human error. I will assert that the conservation in the UK is in need of change and this should be implemented through the combination of these new technologies and the application of minimal intervention8, removal of dirty varnishes and non-original additions, and the utilisation of visible restoration for the process of inpainting.
7 Reversibility, in the context of remedial conservation, is the idea that anything that is done to a work of art should be able to be undone. This is a key principle of minimal intervention. 8 Minimal intervention can be defined as an attitude in which the conservator intervenes as less as possible and only carries out work on the painting to preserve its stability and reduce the possibility for further degradation whilst avoiding conducting any extreme alterations such as transferring the painting to another support. Such measures are only taken if absolutely necessary. 17
Chapter 1: Support Strengthening
The strengthening of the support is often the first active stage in remedial conservation following an examination of the piece. This is fundamental to ensuring that the work is stable and any further conservation work, such as cleaning and retouching, is safe to be carried out on the painting. Significant changes have occurred in the attitudes and methods concerning the strengthening of a painting’s support since the 1970s. ‘Minimal intervention’ is now the generally accepted attitude implemented in conservation treatments in the UK, hence why the transfer of
Cima da Conegliano’s The Incredulity of Saint Thomas (figure 4) onto a new support was such a rare example of such extensive restoration of a painting’s support. Minimal intervention is closely associated with reversibility and arose from a belief in objectivity.9 It first came to the forefront of discussions into the application methods of conservation at the Greenwich Conference on
Comparative Lining Techniques held at the National Maritime Museum, Greenwich in 1974.10 This conference proposed minimal intervention as a response to the extreme treatments seen in earlier conservation efforts. Although the conference focused specifically on the lining of paintings, it showed a change in the mentality of conservation more generally. Consequently, minimal intervention and reversibility became fundamental principles from the 1970s onwards.11
Minimal Intervention
Minimal intervention is a means of preserving the object through avoiding unnecessary interference, which may cause a reduction of the original materials, and only intervening when necessary. Since the Greenwich conference conservation has taken a turn to prioritise the object’s
9 Caroline Villers, "Post minimal intervention." The Conservator 28, no. 1 (2004): 3. 10 Caroline Villers, Lining Paintings: Papers from the Greenwich Conference on Comparative Lining Techniques, (London: Archetype Publications Ltd, 2003). 11 Villers, Post Minimal Intervention, p. 3. 18 history. This can be seen in the changing priorities in structural treatments; the rejection of radical treatments, such as transfer, have been dismissed in favour of more gentle treatments. Therefore, conservation no longer privileges the image at the expense of the object’s history, now the latter is taken into consideration and even prioritised.12 Brandi supports the importance of the history, arguing that the physical nature of a work must be prioritised due to its social importance and the physicality of the object being a record of history.13 When discussing whether to keep or remove additions, he argues that, ‘in historical terms, only the conservation of an addition is unconditionally legitimate, whereas its removal always needs justification, or should at least be carried out in a manner that will leave a trace both in record and on the work of art itself.’14 Therefore, this corroborates the argument that the history of a work of art is innately important and should be preserved through minimal intervention.
However, minimal intervention can be considered an ambiguous term. Muñoz-Viñas argues that, ‘the term ‘minimal intervention’ can be considered an oxymoron.’15 He cites Zeno’s paradox as an analogy to explain this; just as the arrow would never reach its target, or Achilles would never reach the tortoise due to always being able to devise a lesser distance for Achilles to travel, it is always possible to think of a lesser form of intervention one may have taken.16
Aileen Nibet disputes the ambiguity of minimal intervention. She argues that a minimally interventive approach to a work is comprehensively and meticulously defined on a case by case basis to avoid any confusion and make the approach relevant to the particular artwork.17 Therefore, if any uncertainties over minimal intervention and what this means for a work are clarified before every instance of applying this approach to an artwork then it cannot be considered ambiguous.
12 Ibid. p. 5 – 6. 13 Brandi, Theory of Restoration, p. 49. 14 Ibid. p. 68. 15 Salvador Muñoz-Viñas, “Minimal Intervention Revisited” in Conservation: Principles, Dilemmas and Uncomfortable Truths ed. Alison Richmond and Alison Bracker (London: Victoria and Albert Museum, 2009). p. 49. 16 Ibid. 17 Aileen Nisbet, (Paper Conservation Technician the Hunterian Museum and Art Gallery, Glasgow), interviewed by Madeleine White, Glasgow, November 2016.
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Thus, this makes minimal intervention the preferable method for the restoration of a painting’s support as it avoids any unnecessary alterations that might endanger the original and only implements changes that are needed in order to prevent any more of the original form being lost.
Therefore, the attitude of minimal intervention can be seen to safeguard the original work.
Jacqueline Ridge goes beyond minimal intervention, advocating the use of benign neglect, ‘I am a big believer in benign neglect’,18 due to the ambiguities faced when implementing the attitude of minimal intervention, ‘the very word essential; what is essential? You've only got to look at the history of conservation and restoration practice. The lining was deemed essential in the nineteenth century but it isn't deemed essential now.’19 Ridge argues that due to the dangers of causing irreversible change in a work of art, it is hard to justify intervention, ‘there is no question that if you don’t do anything the artworks will carry on existing in some form for ages. On the whole, something pretty catastrophic has to happen for this not to be the case. So, it is quite hard to justify doing even the most minimal stuff on that basis.’20 Although caution is imperative to successful conservation, denying a work any form of intervention can be seen to have harmful consequences.
Neglecting a painting would not only allow a work with significant losses to remain in a state of fragmentation which would be difficult for a viewer to interpret, but the work may not even be safe to display due to a lack of structural stability, removing any possibility of interpretation from the public. In the case of Cimabue’s Crucifixion (figure 1), without intervention this work would have deteriorated rapidly, causing irrevocable damages which were able to be prevented through the process of interventive remedial conservation. Moreover, as a devotional piece, it is an active work and thus the public had a right to be able to view it due to being a fundamental aspect of their religion and culture. Thus, although over-enthusiastic restoration would be detrimental to a painting, it is often necessary to intervein in some manner for the stability of the piece.
18 Jacqueline Ridge, (Keeper of Conservation at National Galleries of Scotland), interviewed by Madeleine White, Edinburgh, November 2016. 19 Ibid. 20 Ibid. 20
The Greenwich Conference
The Greenwich conference was radical in the sense that it called for a halt in what was believed to be a beneficial process.21 The attitude of minimal intervention and the idea that doing nothing at all might be the most beneficial way in which to proceed seems commonplace now but at the time of the Greenwich Conference this was a radical and profound change in the attitudes surrounding conservation22. Resultantly, since the 1970s there has been a large upheaval and re- assessment of how conservation should treat canvas paintings structurally.23 Westby Percival-
Prescott’s keynote address, The Lining Cycle questioned, for the first time, the lining of canvas paintings.24 Percival-Prescott proposed when lining is carried out, minimal heat and pressure should be implemented.25 This had a great effect and after the conference there was a sudden introduction and surge of research regarding low-pressure suction tables in Europe and the United
States.26 Although lining is sometimes still required,27 it is now carried out under precise amounts of humidity, heat and pressure.28 Today, alternative ways of preserving and repairing paintings are being used. For example, Camille Pissarro’s Fox Hill (figure 5), which was wax lined on a vacuum hot table in 1976,29 would today be treated much differently. The restoration would be far less dramatic, one would simply repair the small hole with a thin patch and the edges may be reinforced with fabric similar to gossamer in order for the canvas to be tightened as needed.30 This would have avoided the flattening of the paint surface and preserved the texture and impasto.31 Thus, this
21 David Bomford, “The Conservator as Narrator: Changed Perspectives in the Conservation of Paintings” in Personal Viewpoints: Thoughts about Painting Conservation ed. Mark Leonard, (Los Angeles: Getty Publications, 2003). p. 6. 22 Ibid. p. 8. 23 Ibid. p. 7. 24 Westby Percival-Prescott, “The Lining Cycle” in Issues in the Conservation of Painting, ed. David Bomford and Mark Leonard, (Los Angeles: Getty Publications, 2004). p. 249. 25 Ibid. p. 264. 26 Bomford, The Conservator as Narrator, p. 7. 27 David Bomford, with Jill Dunkerton and Martin Wyld, A Closer Look: Conservation of Paintings, (London: National Gallery Company Limited, 2009). p. 42. 28 Ibid. p. 43 29 Bomford, The Conservator as Narrator, p. 4. 30 Ibid. p. 6. 31 Ibid. 21 reiterates the benefits of minimal intervention and the advantages of not being over-zealous in one’s remedial conservation efforts.
An Italian Approach
It is not only canvas that degrades and needs intervention. For example, da Vinci’s The Last
Supper (figure 3) had suffered from delamination from the wall support32 and Cimabue’s
Crucifixion (figure 1) panel piece was greatly damaged in the 1966 Florence flood. Due to the significant extent of the damage seen in Cimabue’s Crucifixion (figure 1), the restoration process was extensive. Although Italy, like the UK, adopts the attitude of minimal intervention when treating a painting’s support, in this case the minimum that could be done to stabilise the work was extensive restructuring. The support is constructed of both panel and canvas, thus making it complex in nature and needing a variety of conservation methods for the different materials.
Umberto Baldini and Ornella Casazza note in their book detailing the restoration which they undertook that the Crucifixion is made up of ‘a wooden support, canvas glued firmly to it, a layer of gesso33 and size (the so-called priming or ground) and a layer of paint.’34 A support structure such as this which has very dissimilar materials is in need of a variety of intervention techniques; the first of which would be a controlled environment to provide stability while the layers of support dry.
Therefore, the Crucifixion was transferred to the Limonaia of Boboli which kept the work in climatic conditions to allow slow drying so any preventative conservation could be carried out in
‘slow motion’.35 As the material layers do not dry at the same speed and resultantly cause a loosening of the paint, a separation of these layers was required.36 After this separation had occurred, conservation of the canvas began. This comprised of attaching small strips of cotton
32 Pinin Brambilla Barcilon, and Pietro C. Marani. Leonardo: the last supper. (Chicago: University of Chicago Press, 2001). p. 341. 33 Gesso is a hard compound of plaster of Paris or whiting in glue, often used as a foundation layer for gilding or paint to be applied on top of. 34 Baldini and Casazza, The Cimabue Crucifix, (Florence: Olivetti, 1982). p. 26. 35 Ibid. p. 27. 36 Ibid. p. 26 – 27. 22 material along the joints of the previous cuts and a renewed protection of the painted surface by attaching rice paper and mastic which allowed for more solidity and elasticity of the paint. This would make following work on the rear of the canvas easier.37 Once the separate layers were consolidated and restored separately, they were reunited with one another. However, in order to protect each material layer from the interference of other layers, protective films were used in- between the different materials. For example, ‘the paint, with its original gesso ground and canvas, was not attached directly to the wood. Instead, it was bound with an infinitely viscous, and thus removable, adhesive to a layer of resin only a few tenths of a millimetre thick.’38 Moreover, the original nails were replaced with an isolation layer of resin to prevent them from coming in contact with the wood.39 Indeed, a new support was fashioned for the whole crucifix to separate the panel from the canvas and paint, while providing a suitable support for the latter layers that evened out some of the irregularities caused by the warping of the wood.40 This is a very drastic but necessary conservation which is unusual in Italy where the attitude of minimal intervention is prioritised.
Therefore, this highlights the applicability of an attitude of minimal intervention to many different works of art. The ability to define the specifics of what is necessary to be conducted on a case by case basis allows conservation to be appropriate to each individual work.
Similarities to the UK’s Approach
A similarly rare case of radical intervention based on necessity was seen in the National
Gallery, London’s restoration of Cima da Conegliano’s The Incredulity of Saint Thomas (figure 4) where in which the painting was transferred onto a new support during the 1970’s and 1980’s.
Although this extreme conservation measure was ‘extensively practiced (often unnecessarily) in the eighteenth and nineteenth centuries […] It is nowadays only carried out as a last resort,’41 It was
37 Ibid. p. 32. 38 Ibid. p. 29. 39 Ibid. p. 28, 33. 40 Ibid. p. 38. 41 Bomford, with Dunkerton and Wyld, A Closer Look, p. 74. 23 found to be necessary for this painting to be transferred onto a new support following an inspection by Arthur Lucas (the National Gallery’s first Chief Restorer) in 1969, where he aimed to make the painting fit for public exhibition.42 However, Lucas found that the blistering ‘was so severe that, if the facing paper were removed, paint would spring off even when the picture was lying flat.’43
Even following the gradual removing of the facing paper and the removal of old varnish and retouchings, when blister-laying was attempted again it proved to be unsuccessful once more.44
Indeed, in some areas, due to woodworm and dry-rot having reduced the panel, there was ‘nothing underneath the paint and ground layers to which they could be secured.’45 Therefore, although an irreversible and radical treatment, it was deemed necessary to transfer the gesso and paint onto a new support. This laborious process of using sharp hand-held tools to gradually scrape away the wood, layer by layer, lasted several years.46 Once separated from the wooden panel, the buckling was addressed using a Melinex (polyester foil) covered hot table which was heated to 40°C at a pressure of 15mbar for one hour.47 This gradually reduced the buckling until the picture was ‘flat and relaxed’.48 The picture was then attached to stretched and treated linen using ‘the same procedure as for ‘nap-bond’ Beva49 lining.’50 Following this step, the final layer of facing was removed ‘and the picture was found to be securely attached to the linen, with the texture on the front unaltered.’51 This illustrates the positive effects The Greenwich Conference had on improving lining techniques; although now only used as a last resort, the techniques by which to accomplish
42 Martin Wyld and Jill Dunkerton, “The Transfer of Cima’s ‘The Incredulity of S. Thomas’”, National Gallery Art Bulletin, vol. 9, (1985): 44. 43 Ibid. p. 44 – 45. 44 Ibid. p. 45. 45 Ibid. 46 Bomford, with Dunkerton and Wyld, A Closer Look, p. 74. 47 Wyld and Dunkerton, The Transfer of Cima’s ‘The Incredulity of S. Thomas’, p. 55. 48 Ibid. 49 ‘BEVA® 371 Film is solvent free and does not adhere to anything before it is activated with either heat or solvents. It can be inserted into loose areas, and delaminating paint can be properly aligned while the adhesive is inactive. The adhesive can then be activated with a hot air gun, tacking iron or vacuum heat table at a temperature of 150° F or 65° C. The hot air gun technique eliminates any staining and is least harmful to the texture of the painted surface.’ Conservation Support Systems, General Information About Beva® 371 Film, http://www.conservationsupportsystems.com/system/assets/techdocs/Beva_Film_Instructions.pdf, [Accessed: 01/03/2017]. 50 Ibid. p. 57. 51 Ibid. 24 lining without damaging the surface of the painting had dramatically improved, even by the 1980’s, when this conservation was completed, just a decade after The Greenwich Conference. Once lined, the picture was attached to the aluminium honeycomb and fibreglass panel using heat, a procedure which had been used many times before.52 This was a great success and the surface of the paint was not affected by this dramatic support transfer, ‘The wood-grain pattern in the paint was as visible after the restoration as it was before, and the joins in the panel remained equally clear’.53
Although this level of intervention may appear extreme, without such conservation of the painting’s support it would have remained in a very fragile state, vulnerable to irrevocable damage and unable to be shown on display. Therefore, the National Gallery’s restoration is a form of minimal intervention, especially considering the timing of the conservation which took place shortly after the influential Greenwich Conference. Minimal intervention is an ethically idealistic attitude for the practice of conservation. Although the term can be seen to be open to interpretation, this can in fact be seen as advantageous in the case of conservation or reconstruction of a painting’s support due to the necessity of assessing such intervention on a case by case basis. Therefore, minimal intervention should continue to be practiced in the future of conservation in the UK.
Looking Towards the Future of Support Strengthening
By implementing the attitude of minimal intervention, one can be seen to be abiding by the appropriate ethical guidelines, due to a willingness to intervene where it is necessary for the painting’s stability and cohesion, but without conducting restorative measures further than is essential for the preservation of the painting. Applying 3D scanning and printing techniques to this process could improve the level of accuracy and reversibility, both of which are fundamental traits of minimal intervention.54 A 3D scan would provide an accurate digitalised reconstruction of the
52 Ibid. 53 Ibid. p. 58. 54 Caroline Villers, "Post minimal intervention." The Conservator 28, no. 1 (2004): 3. 25 painting55 which the conservators could work upon digitally, experimenting with different techniques of structural restoration to see which would work most favourably with the materials present in the painting in question, much like a surgeon would when designing a custom built part for an operation.56 A conservator could work with a piece 3D modelling software such as 3DS
Max, Maya, Mudbox, or Zbrush, where they could translate the 3D scan into Computer Aided
Design (CAD) data and manipulate this design to respond to different interventive techniques before anything was carried out on the object itself.57 The conservator could then use a computer- aided manufacturing (CAM) programme to create layered cross sections of the object from the manipulated CAD data.58 They could then feed this information into a 3D printer and print accurate pieces to strengthen the painting’s support.
In the case of Cima da Conegliano’s The Incredulity of Saint Thomas (figure 4), this could have enabled the conservators to produce the curvature seen on the original panel which Wyld and
Dunkerton explain was not possible to recreate on the aluminium honeycomb and fibreglass panel:
Some of the planks had a very slight convex warp across their grain […] but it would have been very difficult to preserve the warping in its original form after transfer. The warping could have been imitated by building up the back of the gesso before attaching it to the linen, or by making very shallow corrugations on the honeycomb panel, but to achieve an authentic effect on such a large picture might have been impossible.59
Therefore, the ability to exactly reproduce every fluctuation of the surface to a fraction of a millimetre through 3D scanning and printing60 would allow more accurate support strengthening
55 Blais et al. "Ultra High-Resolution 3D Laser Colour Imaging of Paintings: The Mona Lisa by Leonardo da Vinci." 7th International Conference on Lasers in the conservation of Artworks, Madrid, Spain, (2007): 1 – 2.
56 Fabian Rengier et al, "3D printing based on imaging data: review of medical applications." International journal of computer assisted radiology and surgery vol. 5, no. 4 (2010): 338. 57 Barry Berman, "3-D printing: The new industrial revolution." Business horizons vol. 55, no. 2 (2012): 156. 58 Bethany C. Gross et al. "Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences" Analytical Chemistry, vol. 86, no. 7, (2014): 3241. 59 Wyld and Dunkerton, The Transfer of Cima’s ‘The Incredulity of S. Thomas’, p. 58. 60 Guy Godin, et al. “Active Optical 3D Imaging for Heritage Applications”, IEEE Computer Graphics and Applications, vol. 22, no. 5, (2002): 32. 26 tools or support reconstructions to be produced, thus enabling greater levels of stability and aesthetic cohesion.
Chapter 2: Cleaning
The UK’s Approach to Cleaning
An important stage in the conservation process and one that can transform a work of art either positively or negatively, is cleaning. This is usually defined as ‘the removal of dirt, discoloured varnish layers and non-original repaints from its surface.’61 Cima da Conegliano’s The Incredulity of Saint Thomas (figure 4) by the National Gallery, London, removed the dirty varnish and previous additions that did not make up part of the original paint layers.62 Some art historians, such as
Brandi, may argue that repaints, retouching and additions, subsequent to the original, should be maintained due to becoming part of the objects history and to remove them would reduce their ability to act as an historic document.63 However, with repeated conservation efforts over the years, retouching the paint and consolidating the support, de Clerque suggests that at some point the work of art ceases to be the original and becomes a copy.64 This could be seen to be the case in da
Vinci’s The Last Supper (figure 3); the wall painting now occupying the space could be referred to as a successor to the original due to the considerable amount of work conducted on it over the years.65 In Pinin Brambilla Barcilon’s recent conservation, she removed all previous retouching efforts, restoring the work to its original paint layers, thus allowing the painting to be considered as
61 Bomford et al, A Closer Look: Conservation of Paintings, p. 45. 62 Wyld and Dunkerton, The Transfer of Cima’s ‘The Incredulity of S. Thomas’, p. 45. 63 Cesare Brandi, Theory of Restoration, ed. Giuseppe Basile, trans. Cynthia Rockwell, (Florence: Nardini Editore, 2005). p. 65. 64 De Clerque, The Metaphysics of Art Restoration, p. 271. 65 Ibid. p. 274. 27 a genuine da Vinci and not a copy in place of the original. This parallels the conservation of
Conegliano’s The Incredulity of Saint Thomas (figure 4), with its history of manifold restorations and retouching,66 it too would be in danger of becoming a copy of itself were it not stripped of these falsifications for the original paint to be revealed.
The origin of a work of art can be seen to be fundamentally important to the work as a whole, not only due to giving insights into how and why the work was created but also due to the importance of provenance and providing a historical document of the time and place in which it was created. Prioritising the origin of a work also allows one to read an emotional depiction of the artist’s inner self. Salas suggests that, ‘Seeing emotion in the work means seeing life there as well’.67 This allows the viewer to gain a greater understanding of the artist themselves and the moment of creation which is fundamental to Art History. This would be greatly diluted if repaints, additions and deceptive retouching remain; the viewer would struggle to differentiate between the original and the additions. Therefore, the role of the conservator can be seen as extremely important in maintaining a balance between the originality and the aesthetic readability of the work.
Therefore, a combination of removing any non-original additions with an application of visible restoration, would allow viewers to gain a deeper appreciation of the art in front of them due to an ability to understand the ravages time has had upon a piece of art, whilst still being able to read the composition through the implementation of methods such as colour abstraction following the cleaning process.
Italy’s Approach to Cleaning
Italy’s approach to conservation has been heavily influenced by the writings of Cesare Brandi.
Brandi supports the importance of the history of a painting, arguing that the physical nature of a work must be prioritised due to its social importance as a record of history.68 When discussing
66 Wyld and Dunkerton, The Transfer of Cima’s ‘The Incredulity of S. Thomas’, p. 38 – 42. 67 Charles G. Salas, The Life and Work: Art and Biography, (Los Angeles: Getty Publications, 2007), p. 12. 68 Brandi, Theory of Restoration, p. 49. 28 whether to keep or remove additions, he argues that, ‘in historical terms, only the conservation of an addition is unconditionally legitimate, whereas its removal always needs justification, or should at least be carried out in a manner that will leave a trace both in record and on the work of art itself.’69
This corroborates the argument that the history of a work of art is innately important and should be preserved through minimal intervention. In line with Brandi’s argument, the object can be seen as a source of historic record, which has passed through numerous times and cultures;70 not just showing the influences of when it was created, but also the different viewpoints and influences in conservation practices throughout the time it has been in existence. Indeed, when restoring
Cimabue’s Crucifixion (figure 1), Baldini and Casazza refused to remove any previous retouching work or additions, believing them to be part of the work’s history and thus should not be subtracted from the piece.71 However, this approach to cleaning is damaging to the authenticity of the artwork as such additions camouflage the original amongst layers of non-original embellishments.72 The latter view can be seen to have been substantiated in Pinin Brambilla Barcilon’s remedial conservation of The Last Supper (figure 3), which although was conducted in Italy, adopted the
UK’s approach of removing all non-original additions and returning the work to its original paint layers, thus endorsing more thorough cleaning as more ethically justified.
The Cleaning of The Last Supper
Pinin Brambilla Barcilon’s most recent restoration of Leonardo da Vinci’s The Last Supper
(figure 3) (1979 to 1999) showed an unconventional approach to the way in which it was cleaned; the process falling more in line with the UK’s methods than with Italy’s which has resulted in much controversy. Sheldon Keck provides a summary of the opposing viewpoints in the discussion surrounding radical cleaning:
69 Ibid. p. 68. 70 Ibid. p. 65. 71 Baldini and Casazza, The Cimabue Crucifix, (Florence: Olivetti, 1982). p. 28 – 29, 42 – 43. 72 De Clerque, The Metaphysics of Art Restoration, p. 271. 29
Some viewers, conditioned by pleasant memories of a painting’s earlier appearance, are surprised, even shocked, when they see it freed of grime and discoloured varnish. In fact some are outraged and even vehemently critical of what they call “flaying” of the painting. Other viewers are pleased by the freshness of the colours, the expanded scale of values and the improved visibility of nuances and details.73
Despite the initial shock of a strikingly different aesthetic, the cleaning of paintings is an advantageous measure due to allowing the illumination of previously hidden details and removal of inconsistent additions. In Barcilon’s cleaning, The Last Supper (figure 3) was freed of previous restoration attempts which had obscured the original paint layers. Prior to this, The Last Supper
(figure 3) was ‘scarcely legible due to an overall, uniform darkening.’74 Layers of dust covered the painting, and repaints covered not only the lacunae but the original paint as well.75 Indeed, the back wall of the composition was almost entirely repainted.76 Through the cleaning of the painting, the true nature of the original began to be illuminated which had been hidden for years. The correct proportions of the table legs and stool were seen77 along with the original perspective becoming clarified and reconstructed, which also revealed an inconsistency between the perspective solution and the coffering which defines the ceiling. The proportions of the room have been demonstrated, through this cleaning process, to be quite different to what has been believed prior to Brambilla
Barcilon’s intervention, due to previous repaints masking the truth.78 Another inconsistency can be found in the head of Simon, the dimensions of the head, the beard and his facial features can be seen to be significantly different to the repaints which had overlaid the original.79 These key differences highlight the importance of the cleaning process. Without this intervention, the original
73 Sheldon Keck, “Some Picture Cleaning Controversies: Past and Present”, Journal of the American Institute for Conservation, vol. 23, no. 2, (1984): 73. 74 Brambilla Barcilon and Marani. Leonardo: the last supper, p. 333. 75 Ibid. 76 Ibid. p. 349. 77 Ibid. p. 404. 78 Ibid. p. 343. 79 Ibid. p. 362 – 363. 30 painting would still be masked by layers of inaccurate repaints, thus providing the viewer with a false image and a skewed perspective of da Vinci’s oeuvre.
Numerous discoveries were also made during Brambilla Barcilon’s cleaning process. The presence of doors between the hanging tapestries, as seen in the earliest copies of the painting, were confirmed80 and support hooks for the tapestries were revealed.81 Additionally, the cleaning of the figures’ clothing allowed the study of da Vinci’s sfumato technique. It is such clarifications and discoveries that provide justification for such a radical cleaning. Portions of the original paint had been irreversibly lost but this was Brambilla Barcilon rightly claims that these can be defended by
‘the recoveries, discoveries and information gained by the restoration, along with the restitution of a more reliable image.’82 A more readable, accurate painting showing the original hand of the artist and paints used is far more preferable to a painting which hides the original under layers of repaints and additions.
Looking Towards the Future of Cleaning
Looking towards the future in UK conservation, 3D scanning could be an invaluable tool which would not only produce a visual restoration of the painting through the manipulation of CAD data but also help to guide the actual restoration of the work.83 This would provide more accurate and tracible cleaning.84 Such scanning capabilities allow one to foresee the result of the cleaning process through manipulating the scanned information digitally and observe how the painting might respond to different cleaning techniques.85 Resultantly, this can be used to decide which cleaning method will produce the best result.86 This would allow cleaning in conservation to become more
80 Ibid. p. 345. 81 Ibid. p. 346. 82 Ibid. p. 343. 83 Mauro Barni, Anna Pelagotti and Alessandro Piva, “Image Processing for the Analysis and Conservation of Paintings: Opportunities and Challenges”, IEEE Signal processing magazine vol. 22, no. 5 (2005): 143. 84 Ibid. p. 142. 85 Ibid. p. 143. 86 Ibid. 31 accurate, controlled and predictable, as well as providing more detailed and thorough documentation of the process.
Chapter 3: Retouching
The retouching stage of painting conservation can be seen as the most aesthetically significant step as it can completely alter the visual appearance of a work, it is also the stage of conservation where the great disparities between Italian and British conservation are seen. Conservation is a procedure which results from certain cultural values. As Eastop argues, ‘conservation is a social process, and as a component of culture, it is open to different interpretations.’ Thus, one can expect to observe certain difference in the practice due to different ethical principles. Such cultural differences can be seen in the disparities between British and Italian attitudes to retouching. The
Italian approach suggests that conservation should expose and preserve the true condition of a work; the goal of conservation is to make the work appear to have the properties it does truly have, without the input of deception. 87 Alternatively, in the UK the losses are aimed to be visually replicated as accurately as possible so as to provide the viewer with a cohesive and uninterrupted composition,88 as can be seen in the restoration of Cima da Conegliano’s The Incredulity of Saint
Thomas (figure 4A). However, deceptive restoration is detrimental, not only to the authenticity of the work of art, but also to the education of the viewer, as they are often deceived into thinking that such paintings are in a far more pristine condition than is true. Indeed, this can lead an original
87 Rafael de Clerque, “The Metaphysics of Art Restoration”, The British Journal of Aesthetics, vol. 53, no. 3 (2013): 263. 88 Wendy Hartman Samet, “The Philosophy of Aesthetic Reintegration: Paintings and Painted Furniture” in Painted Wood: History and Conservation, ed. Valerie Dorge and F. Carey Howlett (Los Angeles: Getty Publications, 1998). p. 415. 32 work of art to become a simulacrum of itself, ‘at some point in the process of replacement, what we are left with is just a copy of the original work.’89 If a work reaches this stage, it makes one question whether it can still be considered the same, original work of art, or whether it now belongs more to the hand of the conservator, thus highlighting the dangers of deceptive restorations.
Changing Attitudes Surrounding Conservation
The changing canon of Art History can be seen to have had an influential effect upon conservation due to tastes, preferences and beliefs of the time influencing the way in which conservation was implemented. This can be seen in the now widely favoured principle of ‘minimal intervention’ which was uncertainly suggested in the 1970s.90 This shows that the attitudes towards methods of conservation and art in general have changed through time and the concerns of conservators are subject to the changing social and political environment surrounding them. 91 For example, in 1874 the National Gallery acquired The Story of Patient Griselda, Part I: Marriage
(figure 6) and decided that it was not suitable for display. A restorer was asked to cover the naked figure with drapery (figure 6B). The positioning of her left arm was also altered, presumably due to its initial evocative positioning over her genitalia (figure 6C).92 As tastes change, so do conservation practices, not only through subconscious influences of living in a time with certain priorities and interests, but these cultural changes can lead to conscious decisions to alter a work of art in order to serve the tastes of the time and make the reception of the work more favourable to its audience.
Moreover, the changes in the canon of Art History can be seen to have altered the importance of certain works of art, and to fully appreciate a work of art, one needs to be able to
89 De Clerque, The Metaphysics of Art Restoration, p. 271. 90 David Bomford, “The Conservator as Narrator: Changed Perspectives in the Conservation of Paintings” in Personal Viewpoints: Thoughts About Painting Conservation, ed. Mark Leonard (Los Angeles: Getty Publications, 2003). P. 8. 91 Johnathon Ashley-Smith, “The Basis of Conservation Ethics” in Conservation: Principles, Dilemmas and Uncomfortable Truths ed. Alison Richmond and Alison Bracker (London: Victoria and Albert Museum, 2009). p. 6. 92 David Bomford, with Jill Dunkerton and Martin Wyld, A Closer Look: Conservation of Paintings, (London: National Gallery Limited, 2009). p. 66. 33 recognise its significance93. The cultural significance of a work of art is a social construct,94 thus, if the work becomes more, or less meaningful, this impacts its conservation.95 These changes in significance result in alterations to the conservation attitudes and applications of the said piece as it must be recognised as a work of art for one to implement conservation treatment on it.96
Furthermore, in the last fifty years, the importance of biography has been brought into question by the New Criticism movement. Roland Barthes’s The Death of the Author97 argues that the traditional practice of including biographical analysis within one’s interpretation of a text or a work of art imposes a limitation on that work98. Barthes argues that when one distances their reading of a work from the biographical context, ‘disconnection occurs, the voice loses its origin, the author enters into his own death, writing begins.’99 This suggests that literature and works of art are constructed not as a result of the artist, but can only become a powerful, unlimited work of art when removed from the artist. This suggests that Barthes refuted the importance of provenance and of the work as a piece of historical record. Rather, he prioritises the agency of the work and the way it speaks to its audiences. This would suggest that it is the communication of the composition that should be prioritised; the aesthetic should be maintained through deceptive retouching so that the audiences can read the work without interference and derive their own reaction to the work.
Barthes suggests that it is this reaction that allows the work to truly live on and it is only through the ‘death’ of the creator; the separation of the work from its origins that this is possible.100 When applying this to conservation efforts, one can understand this as an argument for the cleaning of disruptive varnishes and dirt as well as full deceptive reintegration of lacunae. If one prioritises the importance of the work being able to live on through multiple and varied readings and reactions to
93 Jukka Jokilehto, Conservation Principles in the International Context, p. 80. 94 Miriam Clavir, “Conservation and Cultural Significance” in Conservation: Principles, Dilemmas and Uncomfortable Truths ed. Alison Richmond and Alison Bracker (London: Victoria and Albert Museum, 2009). p. 139. 95 Ibid. p. 142 – 142. 96 Brandi, Theory of Restoration, p. 48. 97 Roland Barthes, “The Death of the Author”, in The Norton Anthology of Theory and Criticism, ed. Vincent B. Leitch, 2nd edn. (London: Norton 2010), p. 1322 – 1326. 98 Ibid. p. 1325. 99 Ibid. p. 1322. 100 Ibid. 34 the work, then the maintenance of the aesthetic readability through interventive conservation methods can be understood.
However, this maintenance of the aesthetic at the expense of the authenticity results in negative implications for the work. With multiple retrospective interventions on a work, comes a deterioration of the originality and authenticity. An original work of art can be considered to be a unique way of documenting not only the culture of the time and place where it was created but also provides evidence of the materials and methods favoured the artist. Therefore, deceptive retouching is detrimental to the artwork as it hides the original amongst the hand of the conservator. In a society where we (rightly or wrongly) prioritise the authenticity of a work of art, it is fundamentally important for us to preserve the originality and authenticity of such works. Hiding the original amongst layers of retouching, carried out over decades of conservation efforts, as seen in da Vinci’s
The Last Supper (figure 3),101 therefore seems to be counterintuitive.
Deceptive Restoration
Currently in the UK, deceptive retouching is the generally accepted method. This involves reincorporating the paint losses, or lacunae, into the main body of the painting in a way in which the areas of retouching cannot be distinguished from the original paint layers. This would allow the viewer to read the painting without the interruption of losses which would disrupt the composition and aesthetic legibility of the work.102 Indeed, as Muir suggests, ‘A loss in the paint layer represents a negative alteration that diminishes the value of a work of art, whether aesthetic, devotional or commercial.’ 103 He argues that complete reintegration ‘aims to reconstruct the missing parts of the image by emulating the appearance of the original painting as closely as
101 Brambilla Barcilon and Marani, Leonardo: the last supper, p. 350 – 388. 102 Wendy Hartman Samet, “The Philosophy of Aesthetic Reintegration in Paintings and Painted Furniture” in Painted Wood: History and Conservation ed. Valerie Dorge and F. Carey Howlett (Los Angeles: Getty Publications, 1998) p. 415. 103 Kim Muir, “Approaches to the Reintegration of Paint Loss: Theory and Practice in the Conservation of Easel Paintings”, Studies in Conservation, vol. 54, no. 1, (2009): 20. 35 possible.’104 This implies that such paint losses are detrimental to a work of art both in meaning and value, thus deceptive retouching could be seen as the most favourable course of action in order to obtain greater visual cohesion.
Such deceptive retouching can be seen in the conservation Cima de Conegliano’s The
Incredulity of Saint Thomas (figure 4A). Dunkerton and Roy argue that the disruption to the image caused by the lacunae (figure 4B&C) ‘would only have been slightly reduced if the losses were retouched using one of the clearly visible systems of restoration’.105 However, the National Gallery themselves, for which Dunkerton and Roy are writing for, have implemented a certain level of visible restoration into the conservation of The Incredulity of Saint Thomas (figure 4A). They identify that in restoring certain areas of the composition ‘compromises had to be made.’106
Dunkerton and Roy cite the example of the large area of paint loss on Apostle I:
there was sufficient evidence to reconstruct the folds of the missing sections of the sleeve and of the green cloak, but any folds that may have once been present in the drapery across the figure’s chest could not be re-created. Instead, the internal modelling has been suggested, but not defined, by applying the retouching glazes with a stippled technique.107
This provides evidence for visible restoration as an ethically superior technique as it does not falsify the original through copying what may have once filled the areas of lacunae. Although the stippling technique used in this British example is very subtle and can only be differentiated from a close viewing distance, the fact that it was employed at all by a country which generally advocates deceptive retouching is significant to the ethical boundaries surrounding the inpainting of lacunae.
Therefore, visible restoration can be considered the most advantageous method of retouching, and should thus be used in the future of UK conservation.
104 Ibid. 105 Jill Dunkerton and Ashok Roy, “The Technique and Restoration of Cima’s ‘The Incredulity of S. Thomas’”, National Gallery Technical Bulletin, vol. 10, (1986): 22. 106 Ibid. p. 23. 107 Ibid. 36
Visible Restoration
The alternative Italian method of visible retouching would allow the compositional harmony to be maintained by using methods such as tratteggio108 or chromatic abstraction, while allowing the important distinction between original and non-original to be made.109 Additionally, visible restoration would also provide the viewer with an honest depiction of the work’s condition, as opposed to deceiving them through extensive inpainting which might compromise the authenticity of the work through a lack of differentiation between the original and the non-original. Although some uninterrupted compositional unity may be lost through visible restoration methods, this can be seen as justified due to allowing the audience to gain a greater understanding of what constitutes the original painting.
Implementing visible retouching would reduce the fear that a work will become a copy of itself when the amount of deceptive retouching outweighs the original paint. This was a concern in da
Vinci’s The Last Supper (figure 3). However, with the recent intervention of Brambilla Barcilon and Marani, the previous repaints and retouching have been removed, leaving distinction between da Vinci’s original work and the visible retouching carried out by the conservator in order to maintain the cohesion of the painting.110 Similarly, Baldini and Casazza implemented visible retouching in their restoration of Cimabue’s Crucifixion (figure 1D&E); a cross hatching variant on the tratteggio technique they term ‘colour abstraction’.111 This technique abstractly incorporates the surrounding colours to reincorporate large areas of loss.112 Baldini and Casazza’s use of cross hatching provided layers of interwoven brush strokes made up of the colours surrounding the lacunae.113
108 Tratteggio is a visible restoration technique that uses vertical hatchings of made up of key colours obtained from the surrounding paint in order to create compositional cohesion without competing with the original. 109 Muir, Approaches to the Reintegration of Paint Loss, p. 22. 110 Brambilla Barcilon and Marani. Leonardo: the last supper, p. 342 – 343. 111 Baldini and Casazza, The Cimabue Crucifix, p. 42. 112 Andrea Roth, “Croce e Delizia”, Personal Viewpoints: Thoughts about Painting Conservation ed. Mark Leonard, (Los Angeles: Getty Publicataions, 2003). p. 16. 113 Baldini and Casazza, The Cimabue Crucifix, p. 46. 37
Chromatic abstraction works on the basis of the human eye blending the colours, as was appropriate to each section, rather than attempting to premix said colours on a pallet before application.114 This method of visible restoration originated from the principles of tratteggio which was based upon the ideas of Cesare Brandi and developed at the Istituto Centrale per il Restauro in
Rome during 1945-50.115 This method differs to that of chromatic abstraction through the application of brush strokes. Where chromatic abstraction uses a cross-hatching technique to apply the separate colours, tratteggio uses vertical lines which measure approximately one centimetre in length. Baldini and Casazza developed upon this method with the aim of making the reintegration of the areas of loss more cohesive with the rest of the composition116 than would have perhaps have been possible if they had used the linear technique of tratteggio which would have contrasted to the curvature of forms. However, they did implement the use of linear brush strokes in the areas which had lost gold gilding. They used different directions of brush strokes to differentiate between separate areas of gilding. For example, they used the small brush strokes to follow the circular pattern of the halo, which contrasts to the vertical pattern of the background.117 Similarly to the non-gilded areas, they selected the colours which would correspond to those in the surrounding areas. In this case they had to approximate the gold colour through the use of the colours it reflected, ‘Since gold is a metal which reflects the colours yellow and red, as well as green owing to the transparency, we used without exception only those colours’.118 Thus, this provides a visually convincing level of cohesion to the composition without competing with the original or falsifying it in any way. Baldini and Casazza can also be seen to have implemented the technique of chromatic selection. 119 This technique addresses the smaller areas of loss, such as the lacunae present in the hair of St. John, by following the movement of the original brush strokes.120
114 Hartman Samet, The Philosophy of Aesthetic Reintegration in Paintings and Painted Furniture, p. 414. 115 Ibid. 116 Baldini and Casazza, The Cimabue Crucifix, p. 42. 117 Ibid. p. 52. 118 Ibid. 119 Ibid. p. 43. 120 Roth, Croce e Delizia, p. 16. 38
Isaac Messina identified limitations seen in Baldini and Casazza’s chromatic abstraction technique such as interfering with the compositional flow due to not treating each section with specificity. He argues that Baldini and Casazza’s restoration ‘presents clear visual problems and disadvantages, particularly when viewed from a distance’,121 and asserts that their restoration
‘swallows the original contours of the composition.’122 Campbell validates this view, claiming that
Baldini and Casazza’s restoration causes ‘the eye to pass from one surviving area of the image to the next’123 and that ‘few observers of this technique judge the theory of colour abstraction to be completely convincing.’124 Indeed, even Casazza has questioned the success of their restoration in hindsight.125 As a result of such doubts over the success of Baldini and Casazza’s restoration,
Messina sought to address these through a reconstruction of an area of the damaged crucifix, namely the area next to Christ’s left hand where St. John the Evangelist is depicted (figure 2).
Messina implemented his own restoration approach with great success. He draws influences from
Baldini and Casazza’s chromatic abstraction technique, while developing it to better delineate the contours of the composition, ‘The most significant difference between Baldini and Casazza’s approach and my own is the conservation of the original forms and contours of Cimabue’s composition.’126 This is most notable in St. John’s thumb; while Baldini and Casazza’s restoration makes the thumb an ambiguous form, with the chromatic abstraction causing it to merge into the saint’s robes, Messina differentiates the forms (figure 2C).127 Messina uses not only linear brush strokes going in different directions depending upon the form they aim to represent, but also uses separate colours to illustrate the different forms that have been lost (figure 2D). This approach is
121 Isaac Messina, “A New Approach to the Restoration of Cimabue’s Santa Croce Crucifix”, (BA diss., Syracuse University, 2014). p. 7. 122 Ibid. p. 76. 123 J.P. Campbell, “Time and Change: Colour, Taste and Conservation”, International Journal of Design & Nature and Ecodynamics, Vol. 4, No. 3 (2009): 264. 124 Ibid 125 Hartman Samet, The Philosophy of Aesthetic Reintegration in Paintings and Painted Furniture, p. 414. 126 Messina, A New Approach to the Restoration of Cimabue’s Santa Croce Crucifix, p. 76. 127 Ibid 39 largely satisfactory due to the differentiation of forms, however due to only applying one colour to each section, Messina’s re-restoration lacks the subtlety of colour present in Baldini and Casazza’s.
With the benefit of being able to examine both of these approaches, one can deduce that the most preferable method of retouching would be to implement a combination of the methodologies shown in Messina’s re-restoration and the original restoration by Baldini and Casazza. One should implement the distinction of forms through separate colours and brushwork which shifts direction depending on form, as was seen in Messina’s work, while also using the chromatic abstraction seen in Baldini and Casazza’s which provides such subtly of colour through a mixture of colours applied in a hatching technique.
Therefore, I propound that the Italian method of visible restoration is implemented in the UK; specifically, a subtler application of Messina’s developed technique of chromatic abstraction. This would not only allow for the differentiation between the original and the non-original, but with the correct method of application and a skilled use of this technique, the visual cohesion of the composition does not need to be sacrificed. With the application of visual restoration, the fear of falsifying the original and transforming an original work into a simulacrum of itself through years of retouching can be eradicated and allows the viewer to decipher the original paint layers and the effect time has on a painting.
Looking Towards the Future of Retouching
For Rothko’s Harvard Murals, (figure 7) the damage observed was not a weak support, dirty or overpainted layers hiding the original, or a matter of paint loss; it was the fading of the original paint which caused drastic changes in their aesthetic appearance. This can be seen to be a result of the unstable Lithol Red paint. Although the dry pigment is in itself, a fairly stable pigment, when mixed with binding medium it is prone to fade.128 Restoring these works to their original colours
128 Jens Stenger, et al, “The Making of Mark Rothko’s Harvard Murals”, Studies in Conservation, vol. 61, no. 6, (2016): 344. 40 through the application of paint would have covered and falsified the original, therefore, it was decided to implement projected light to correct the changes in colour.129 Through studying photographs of the paintings taken soon after completion, as well as allowing for the colours present in the works today, conservators constructed a projection of light which would compensate for the loss of original colour through fading.130 The accuracy of this reconstruction can be questioned due to the photographs themselves fading131 and the necessity to make the projection slightly unfocused to compensate for the fine black line around each pixel.132 However, though the restoration may be imperfect, it allows the viewer to experience the colours of Rothko’s original works, as closely as can be deduced. Thus, this enables the viewer to experience the work in a level of chromatic cohesion much closer to the original impact they would have had. Although this restoration took place in the USA, it exemplifies the willingness of conservators in English-speaking countries in the
Western World to adopt new, innovative technologies which could provide higher levels of accuracy, less invasive techniques and greater reversibility. Indeed, in the case of these murals, in order to reverse the restoration, one needs only to switch off the projector.
Another such option for painting restoration is the implementation of 3D scanning and printing which would provide accurate documentation of an artwork and allow the conservator to work upon the piece digitally, using the visible restoration techniques examined above.133 This would allow the conservator to experiment with the variations of visible restoration techniques, permitting them to define which appeared most successful on the specific case in hand. Additionally, this would enable any mistakes to be eradicated with the ability to simply click an ‘undo’ button to revert to the previous state.134 Once the conservator was happy with the aesthetic appearance of their visible
129 Jens Stenger, et al, “Conservation of a room: A Treatment Proposal for Mark Rothko’s Harvard Murals”, Studies in Conservation, vol. 61, no. 6, (2016): 348. 130 Ibid. p. 352. 131 Ibid. p. 350. 132 Ibid. p. 354 – 355. 133 Barni, Pelagotti, and Piva. Image processing for the analysis and conservation of paintings, p. 143 – 144. 134 Christopher Miller, (Chief Designer and Artist for Multimedia Visual Effects at 3fD (3form Design)), interviewed by Madeleine White, Andover, March 2017. 41 retouching, this CAD data would provide the CAM software with the necessary information to accurately print the inpainting in order to fill the areas of lacunae.135
Through the willingness of conservators to implement new methods of remedial conservation exemplified in the case of the Harvard Murals (figure 7), the possibility of an increase in 3D scanning and the implementation of 3D printing in UK conservation seems yet more imminent.
Chapter 4: The Future of Conservation
Through utilising a combination of 3D scanning and 3D printing this can offer great possibilities for the future of conservation in the UK. If a 3D scan of a work was taken before significant damage occurred, this would allow the conservator to employ the use of a 3D printer to recreate was once there through using the combination of the previous scan and a current scan to identify the areas of loss and reconstruct these digitally. This can be seen as similar to the use of
3D printing in the field of medicine. By implementing medical imaging such as Magnetic
Resonance Imaging (MRI), doctors are able to obtain high-resolution 3D image data.136 This data can then be used to print customised medical implants.137 This is similar to the application possibilities of 3D scanning and printing in restoration; a 3D scan enables the manufacture of specific custom parts to fill areas of loss or support areas of weakness.
This provides vast possibilities. One could use 3D scanning and printing to produce deceptive restoration with a greater level exactitude than manual retouching and a reduction of
135 Gross et al, Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences, p. 3241. 136 Fabian Rengier et al, 3D printing based on imaging data: review of medical applications, p. 335. 137 Robert Bogue, "3D Printing: The Dawn of a New Era in Manufacturing?" Assembly Automation vol. 33, no. 4 (2013): 309.
42 guesswork, assumptions and human error. It could be argued that this would provide an important insight into the painting and one would be able to read every brush stroke as created by the artist, as even if it is a reconstruction it would be exact in colour, depth, density, gloss, texture and every other detail. However, although I strongly advocate the use of digital reconstructions as a means to aid the understanding of a work of art, implementing indistinguishable inpainting onto an original work of art is a form of deception which denies the viewer the ability to differentiate the original from the copy. Furthermore, the lack of deceptive retouching does not mean that the cohesion of the composition needs to be lost; through methods of visible restoration such as chromatic abstraction, this cohesion can be maintained without falsifying the original with areas of replication in the zones which constitute the lacunae.
The most important aspect of the work’s history is its originality. I disagree with the premise of keeping the additions and changes made to a painting following its completion, as is suggested by Brandi.138 Later additions to a painting are not part of the work and therefore should not be maintained.
3D Scanning
A 3D scan can be obtained using a high-resolution optical 3D colour laser scanner which records the exact shape of the object and any fluctuations in the surface such as ‘Subtle heights variations due to brush strokes or paint thickness, cracks, wood grains, and warping.’139 This provides us with an arsenal of information about the object, which is ‘typically digitised at the sampling resolution of 0.5 mm in the x and y directions.’140 This would allow a detailed documentation and analysis of areas which could be vulnerable, thus allowing for appropriate preservative measures to be implemented regarding the structural support and paint layers. It would
138 Brandi, Theory of Restoration, p. 49. 139 François Blais, et al. "Ultra High-Resolution 3D Laser Colour Imaging of Paintings: The Mona Lisa by Leonardo da Vinci." 7th International Conference on Lasers in the conservation of Artworks, Madrid, Spain, (2007): 2. 140 Godin, et al. Active Optical 3D Imaging for Heritage Applications, p. 32. 43 also offer a greater understanding of the painting before cleaning took place. For example, the
National Research Council of Canada (NRC) undertook a complete 3D scanning of the Mona Lisa
(figure 8), obverse and reverse, in order to study the structure of the painting and the techniques employed by da Vinci.141 Such a scan would also enable the conservator to virtually clean the painting, experimenting on a computer programme which would allow them to decipher the most advantageous method before implementing this onto the actual painting, thus reducing the risk of error and increasing the likelihood of the application of a satisfactory method.142
Moreover, 3D scanning a painting would benefit the retouching of that work. Barni et al distinguish two possible ways in which a 3D scan could benefit this process: through computer- guided restoration, or through the construction of a digitally restored work of art.143 Although both of these are hugely beneficial to the restoration of a work of art, I propose a third, more favourable option; employing the 3D scan in the production of CAD data in order to construct a 3D printed restoration. This would fill the lacunae using the same visible restoration techniques seen in traditional methods of retouching without the danger of human error (which would still be present in computer-guided restoration). While the production of a digitally rendered reconstruction would remove this level of human error, it does not help to bring the original work of art into a greater degree of cohesive unity, rather it can only supplement it through visuals being provided of the reconstruction next to the original work. Contrastingly, using a 3D scan to create 3D printed in- painting, directly onto the painting, would allow the conservator to work with an accurate 3D depiction of the original work, using techniques such as chromatic abstraction to fill the lacunae using CAD software to create CAD data144. This would permit the conservator to experiment with
141 Blais et al, Ultra High-Resolution 3D Laser Colour Imaging of Paintings, p. 2. 142 Barni, Pelagotti, and Piva. Image processing for the analysis and conservation of paintings, p. 142. 143 Ibid. p. 143. 144 One would implement the use of CAD software to create CAD data. CAD data is a broad term which includes different file formats. One such file format is a .STL (Standard Tessellation Language or Stereo-Lithography) file. A .STL file is often used when working with a 3D scan; the 3D scanned information is translated into triangulated sections which are stored in a .STL file. This information can be manipulated by using a CAD programme which would then be translated back into an .STL file to be exported into CAM software. CAM software translates the virtual object into one that can be made into reality and manufactured by deciphering how to create the object. This information is then sent to 44 different materials and techniques on the CAM software to see how they would react with the original materials and how successful the aesthetic cohesion would appear before applying the printed materials onto the original work.
3D Printing
3D printing allows the digital world to be brought into reality through translating virtual modelling into a series of cross sections which can be printed through layering materials on top of one another.145 There is a variety of 3D printing techniques for different materials and purposes.
One of the most common is a material extrusion technique known as Fused Deposition Modelling
(FDM). This technique melts the material which can then be piped in both horizontal and vertical directions.146 This is controlled using CAM software to create layered cross sections of the object from CAD data which would have been created using either a 3D modelling application or a 3D scanner to copy an existing object such as the digitisation of the of the Nisga’a Woodpecker-shaped rattle.147 In the process of digitalising the rattle, a high-resolution colour-range sensor was used which took thirty images of the rattle, covering its entire exterior and all its surface fluctuations.148
This method of 3D scanning is commonly known as photogrammetry. This information was then converted in to 1.3 million triangles with a resolution depth of 0.01mm.149 This was done to obtain a highly detailed documentation of the object, allowing one to document changes to the object over time, as well as providing remote access to the object for educational purposes.150 However, one could develop the use of this 3D imaging data. If the object is damaged, one could manipulate the
the 3D printer which interprets the information by converting the information into a G-file via slicer software present in the 3D printer. Gross et al, Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences, p. 3241. 145 Alexandru Pîrjan, and Dana-Mihaela Petrosanu. "The impact of 3D printing technology on the society and economy." Journal of Information Systems & Operations Management vol. 7, no. 2, (2013): 361. 146 Gross et al. Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences, p. 3243 – 3244. 147 Godin, et al. Active Optical 3D Imaging for Heritage Applications, p. 27. 148 Ibid. 149 Ibid. 150 Ibid. 45 virtual model using CAD software; custom making parts to help strengthen any structural weaknesses, using the 3D digital model for computer-guided cleaning and virtually infilling any losses of paint with the Italian technique of chromatic abstraction. One could then translate these modifications into an .STL file to be fed to a 3D printer via CAM software for the visualised parts to be printed into reality.
During an interview with Christopher Miller, Chief Designer and Artist for Multimedia
Visual Effects at 3fD, he explained how 3D printing has provided the design industry with an unprecedented method of producing prototypes of increasing quality and strength for many years.151
Miller works with an FDM 3D printing machine as this is the most effective for producing rapid prototypes; a necessary part of his business. He explained how there had been ‘a huge push to grow the capabilities of this technology and reduce the overall cost’152 due to the high value they hold for businesses such as his. 3D printers are now able to rapidly print parts to an extreme degree of accuracy using a vast range of materials and Miller argues that for this reason, ‘I feel strongly that there are many opportunities for such methods to be applied in the restoration of paintings as FDM printing is capable of producing very accurate and strong components consisting of many different materials.’153 Indeed, FDM could be advantageous to the conservation of supports through custom built plastic reinforcements, which would not be as vulnerable to degradation as wood. However, there are more advantageous 3D printing techniques available for the retouching of paint layers such as Material Jetting. This technique applies the material, in this case it would be paint, in droplets. This process is much like a common 2D printer but the layers are built up by the material being applied to the same area in layers then hardened by ultraviolet (UV) light.154
Combining these printing techniques with 3D scanning technology allows for exact replications to be created of the object in hand.155 Therefore, if paintings were scanned upon arrival
151 Miller, Interview. 152 Ibid. 153 Ibid. 154 Pîrjan and Petrosanu, The impact of 3D printing technology on the society and economy, p. 362. 155 Miller, Interview. 46 at a gallery then most of the key information that a restoration requires could be stored.156 The 3D geometry of the painting and its canvas would be calculated as well as the chemical composition of the components making up the paint layers.157 Miller corroborated my hypothesis that 3D scanning and 3D printing could be used to help aid the conservation of paintings. He states that, ‘being able to gather this data would allow for sections of the painting to be printed should any part of it become damaged.’158 If however, the painting had not been scanned then the use of 3D printing would not be made redundant. Instead, ‘the data could be produced within a digital 3D environment where the geometry could be modelled by a digital artist.’159 This would allow for mistakes to be made within the digital environment that would be easier to correct than if they were produced by an artist painting directly on to the canvas. Once this digital replication of the damaged section of the painting had been created the 3D printer would be able to print onto the canvas and even repair sections of the canvas itself.160 Moreover, Miller asserts that anything that was done to the work of art would be completely reversible, ‘Any 3D printing carried out on an artwork would be completely reversible if the 3D build data was stored. This data would essentially build a map of any alterations that had been made. With this information, a process could be developed that would enable a robotic device to remove the unwanted material from the painting to the same degree of accuracy that it was applied.’161 Thus, the application of 3D scanning and printing can be seen as the obvious choice to implement in the future of conservation in the UK due to the level of accuracy and reversibility it provides. Whilst Miller’s expertise is based in a different industry, the conservation of art should make the best use of new technology to advance the techniques of restoration. Therefore, when considering the future of conservation in the UK, one must consider
156 Barni, Pelagotti, and Piva. Image processing for the analysis and conservation of paintings, p. 141. 157 Ibid. 158 Ibid. 159 Ibid. 160 Ibid. 161 Miller, Interview. 47 new technologies such as 3D scanning and printing and recognise the vast benefits they could provide to the industry of remedial conservation.
Conclusion
Overall, one should strive for stability and aesthetic cohesion without deception when conducting remedial conservation. A painting will not last forever, the materials it is made from will degrade and perish. Conservation measures seek to preserve these works, however, to apply assumptive reconstructions onto the original is to falsify that work. Due to the natural degradation of materials, it is inevitable that such reconstructions will vastly outweigh the original material, thus making the work a simulacrum of its previous self. Therefore, we must strive to avoid this falsity while maintaining a level of readability through the application of visible restoration.
As I have argued, to implement the deceptive restoration, currently used in the UK, misrepresents the original, thus an application of the Italian method of visible restoration is the most ethically satisfactory technique to use. Messina’s developed chromatic abstraction technique would allow the greatest level of aesthetic cohesion to be produced while a differentiation between the original and the non-original was maintained. One could improve upon this approach by combining it with the more subtle application of colour seen in Baldini and Casazza’s restoration, whilst maintaining the distinction of compositional contours.
Looking towards the future of conservation in the UK, the utilisation of new technologies such as 3D scanning and 3D printing could be hugely advantageous for the field. 3D scanning has already proven to be beneficial to the collection of detailed data but it could be further implemented to have an active role in conservation. Such a 3D scan could help conservators carry out computer-
48 aided cleaning after experimenting with different techniques digitally. Furthermore, if such a 3D scan was manipulated by the conservator using CAD software, they could carry out their conservation work digitally and print the custom-built pieces for the strengthening of the supports.
One could also print the precise chromatic abstraction inpainting directly onto the work without the fear of human error and with higher levels of reversibility.
Therefore, I propound that the future of remedial painting conservation should see a combination of 3D scanning and printing technology with an application of Italy’s method of chromatic abstraction, applied digitally into CAD software. This would allow for accurate, reversible results which would maintain the aesthetic cohesion of the painting without falsifying the original.
49
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Appendix: Consent Forms
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