Merces Lorena, Altarpiece painting: a view from the inside, e-conservation Journal 3, 2015, pp. 118-138
Altarpiece painting: a view from the inside
Mankind has always sought to preserve day-to-day and artistic objects. In what concerns paintings, interventions were not necessarily neutral or respectful of the original condition. Very much the opposite, there are a number of examples showing excesses of retouches and repaints, which were carried out as part of the restoration and conservation work. Restoration artisans, many times, and following the owner’s request, did not hesitate repainting over existing damages. Only during the 20th century, the opinion concerning lacunae reintegration changed: professionals started questioning the legitimacy of such interventions in works of art. Interventions should not jeopardize the integrity of artistic production. Over these last few years, several altarpieces were restored in Portugal. Their conservation state varied substantially from one another, mainly due to the existence of opportunistic, isolated interventions, often completely out of context. As a result, the initial prevailing impression is a lack of intervention standards and the uneven character of the conservation and restoration work, namely, in what concerns final retouches and repaints. One of the consequences is that it may lead to mistakes in the historical and artistic characterization. For example, a work of art conceived as a complete set could be perceived as a collection of individual works, as is the case of altarpieces. Nevertheless, today, painting reintegration is still a compromise between historical honesty and aesthetic demands. The fundamental need to respect the original trueness of the object still remains as the defining factor of the boundary of the intervention. In this paper, we review and analyze several examples of restored 16th century altarpieces, all recently restored between 2008 and 2014: the altarpiece of the Virgin of Sorrows by Quentin Metsys from the Madre de Deus church in Lisbon, the altarpiece of the Holy Virgin’s Life from the Cathedral of Évora and the retable from the Cathedral of Funchal in the island of Madeira. In the end, we concluded that, while direct eye observation of the object is fundamental, it needs to be coupled with micro analytical tools along with scientific and analytical methods to ensure the stated result.
In this article we will review the findings and decisions of examples of conservation interventions in three Portuguese 16th century altarpieces performed between 2008 and 2014. Specifically, the altarpiece of the Virgin of Sorrows by Quentin Metsys from the church of Madre de Deus in Lisbon; the retable of the Holy Virgin’s Life from the Cathedral of Évora; and the retable from the Cathedral of Funchal in the Island of Madeira.
We intend to show that the complexity of intrinsic decisions of the conservation interventions, akin to the sets of paintings such as those being presented here, require systematic work and sharing of opinions. The approach taken encourages multidisciplinary research, based on preliminary studies of existing documentation in archives and libraries, coupled with exhaustive analytical work. The studies were designed to define both the criteria and methods of intervention in these altarpiece sets. This resulted in a more "genuine" original, without margin of error for either misreading or interpretation.
A conservation survey was performed prior to the conservation intervention. A set of data on the altarpieces was collected using infrared reflectography, radiography, normal and macro photography under ultraviolet, visible and infrared light using 45º and raking incidence.
Analytical exams were performed to characterize the execution of the painting process and highlight the creative practice, either autonomous or "individual" or in partnership. The obtained results provided data for comparison with other painters’ studios.
The data collected also allowed the team to identify the extension and location of previous interventions through the identification of repainted areas. The material characterization of the paintings allowed the team to define the technical procedures to be adopted on each of the interventions.
The identification of the pigment and their chemical composition was first carried out using X-ray fluorescence spectroscopy, a non-invasive in-situ method. Microsamples were collected and assembled in resin to study all the stratigraphic layers (sections). Each layer was later analysed individually through microscopy techniques. The microscope allowed measuring the thickness and determining the composition of each layer, the structure of it sections, and their particle distribution. Technical tests were carried out with the support of the José de Figueiredo Laboratory, and the HERCULES Laboratory from the University of Évora.
With the exception of the great altarpiece of the Cathedral of Funchal, the remaining two altarpieces were removed from their place of origin. The creative process of each altarpiece needed to be determined with accuracy. The research plan consisted of a direct analysis of selected works, the altarpiece of the Virgin of Sorrows and the altarpiece of the Holy Virgin’s Life and considered three basic approaches: historical research, analysis of the paintings surface and material characterization [1, 2].
3. Altarpiece of the Virgin of Sorrows (c. 1509/11)
The altarpiece of the Virgin of Sorrows is composed of a set of eight paintings commissioned to Quentin Metsys for the Convent of Madre de Deus in Lisbon in 1509 by Queen Leonor of Portugal (1481-1525). Nowadays, it is part of the permanent exhibition of the National Ancient Art Museum (MNAA). The commission was placed through João Brandão, overseer in Antwerp in 1509-14 and 1521-26. It is unknown, however, whether the commission was for a new production or for existing panels . The theme of the Virgin of Sorrows is traditionally represented, and this case is no exception, by a central panel with the Virgin, flanked by seven smaller panels representing the seven sorrows of the Virgin. The specific seven sorrows may vary and in these panels the following were represented: Presentation of Jesus in the Temple, Rest on the Flight into Egypt, Christ among the Doctors, Christ Falling on the way to Calvary, Calvary, Lamentation, and The three Marys with St. John at the Tomb (Figure 1).
Figure 1. Altarpiece of the Virgin of Sorrows by Quentin Metsys from the church of Madre de Deus in Lisbon: 1 - Virgin of Sorrows; 2 - Presentation of the Child in the Temple; 3 - Rest on the flight into Egypt; 4 - Christ among the Doctors; 5 - Christ on the way to Calvary;6 - Calvary; 7 - Lamentation; 8 - The three Marys with St. John at the Tomb. Photos by Jorge Oliveira and Mercês Lorena, DGPC.
The performed analytical tests identified different degrees of degradation and differences in the accumulation of dirt. These differences resulted mainly from past interventions, which occurred during the 20th century. However, existing documental sources refer to other interventions only a few years immediately after their execution. In one of them, the original dimension was changed and the support was cut.
Between 1931 and 1936 the panel of the Virgin of Sorrows was restored by Fernando Mardel at the National Museum of Ancient Art in Lisbon. Based on the intervention report nº 1275 , João Couto, the museum director, wrote in 1937 the following: «…/a laminate cutout is visible on the bottom of the painted panel. This was done so as to fit a tabernacle that was intended to be placed in front of painting. Dr. José de Figueiredo, the previous museum director, told me that he possessed a document dating from the 18th century, which described the placement of the altar in a chapel, and the aforementioned mutilation. According to further information from the same José de Figueiredo, João Couto found in the Madre de Deus convent, a painted fragment, though repainted, fitted well the dimension of the cutout. He brought this fragment to Professor Freire, who then fitted it into the missing cut out redoing the panel in its original format. Professor Freire had already retouched the folds of the robe of the Virgin on this missing part but the restaurateur Fernando Mardel undertook a new study, which resulted in the present version of the panel painting. The painting was varnished with two coats of resin varnish and a thin layer of oil varnish. A layer of protective was also applied to it» .
After the documentary research had been carried out, namely the radiographical and dendrochronological studies, it is now possible to deny the reported information about the originality of the fragment board found by João Couto (Figures 2 and 3).
Left to right:
Figure 2. Virgin of Sorrows - lower applied in embedded ganzepe applied by L. Freire in 1931-36. Photo by Mercês Lorena, DGPC.
Figure 3. Virgin of Sorrows – radiography detail of lower applied in embedded ganzepe applied by L. Freire in 1931-36. X-ray performed by Jorge Oliveira, DGPC.
The dendrochronological study (Table I) demonstrated that the rings of the fragment board of Baltic oak do not correspond to the rings of the adjacent panel [2-7]. Later on, during the material study for the pigments identification, it was again confirmed that this area was completely repainted and that its pigments did not match the timeline of the main panel painting, for example, Prussian blue. Also, the ground layer of the fitted board is different to the original ground layer of the panel (Figure 4), the first being gypsum, while the latter is chalk (Figure 5). The gypsum layer suggests that the fragment possibly belonged to a Portuguese painting for in Flanders gypsum was not used for this purpose. All these results lead to the definitive conclusion that the fragment never belonged to the original panel painting of the Virgin of Sorrows .
The relevance of this finding is not the fact in itself but its consequences to the interpretation of the painting. A totally illusionist retouching lead to errors such as the originality of the pleated robe of the Virgin, which by being so well done, made detection impossible to the naked eye. Nevertheless, in this case, the decision was not to remove the repainting and the fitted fragment. The team considered that the painting should not be presented to the public with that lower mutilation. The previous intervention was thus maintained as performed by L. Freire and F. Mardel in 1931-37 and the present decision recorded (Figure 6).
Left to right:
Figure 4. Virgin of Sorrows: a) location of the sampling point; b) cross section by blue repaint; c) SEM-EDX map of area; d) EDX identification the gypsum ground layer. This ground layer is different to the original ground layer. Analyses by Ana Mesquita e Carmo, DGPC, and Luis Dias, HERCULES Lab.
Figure 5. Virgin of Sorrows: a) location of the sampling point (of hands); b) cross section by carnation; c) SEM-EDX map of area; d) EDX identification of the ground layer in chalk on the layer next to imprimitura chalk and gypsum with a trace in the layer near the bracket. Analyses by Ana Mesquita e Carmo, DGPC and Luis Dias, HERCULES Lab.
Figure 6. Virgin of Sorrows: before (above) and after (below) retouching. Photos by Mercês Lorena, DGPC.
4. Altarpiece of the Holy Virgin’s Life (c. 1500)
The altarpiece from the Cathedral of Évora, flemish painting unknown author, comprises 12 paintings depicting the life cycle of the Virgin: Meeting of St. Anne and St. Joachim, Virgin’s birth, Presentation of the Virgin in the Temple, Annunciation, the Marriage of the Virgin, Nativity, Adoration of the Magi, Circumcision, Flight into Egypt, Presentation of the Child in the Temple, Child among the Doctors, and the Virgin’s death (Figure 7).
The absence of documentation on the construction of the altarpiece, the lack of a custom contract, and of signatures on the panels does not allow its attribution with certainty.
According to some authors, the construction of these panel paintings has an imprecise date placed at the end of the 15th century, somewhere between the changes of reigns of King João II to King Manuel I (1495). The actual order of the altarpiece is linked to the office of Dom Afonso of Portugal, Bishop of Évora between the years 1485-1522.
The cathedral’s main chapel was demolished in 1718 and the panels of the altarpiece were dismantled. In 1944, Tulio Espanca who describes a pastoral visit to the Cathedral in 1537, quotes: «this chapel was dedicated to the Assumption of the Virgin and inside there is a large, beautiful, well-painted and gilded altarpiece. Done as it should be, because it was cleaned recently and with that it was unveiled and was rediscovered» .
With the foundation of the Museum of Évora in 1915, the 12 paintings became part of its collection. The following year, four of those paintings, Presentation of the Virgin in the Temple, The marriage of the Virgin, The Child’s Presentation at the Temple and The death of the Virgin, were taken to the National Museum of Ancient Art, to be restored by Luciano Freire. They remained there until about 1962 . From that date onwards, the panel paintings were reunited and remained together at the Museum of Évora.
Figure 7. The Holy Virgin’s Life: 1- S. Joaquin and Sta. Ana Meeting; 2- Virgin’s Born; 3- Presentation of the Virgin in the Temple; 4- Annunciation; 5- Virgin’s marriage; 6- Nativity; 7- Adoration of the Magi; 8- Flight into Egypt; 9- Circumcision; 10- Presentation of the Child in the Temple; 11- Child Among the Doctors; 12- Virgin’s death. Photos by Jorge Oliveira, DGPC.
Analyzing the previous conservation records, we were able to determine that, during the last century, each different painting was subject to different interventions. This may justify the different state of degradation of each individual painting. According to the records available at Laboratório José de Figueiredo (LJF) document archive, the first intervention by Luciano Freire dates from 1920/30. It records the treatment undergone by four of the paintings: Presentation of the Virgin in the Temple; Virgin’s marriage; Presentation of the Child in the Temple and Virgin’s death. The treatment consisted basically in insect disinfection of the wooden supports. The report also records, in some cases, the removal of repaints on the chromatic layer.
Luciano Freire states in its 1921 conservation report, about the intervention performed to the Marriage of the Virgin: "I carried out still this year, the treatment of one of the four paintings from the collection of the Museum of Évora, deposited at the Museum of Ancient Art» .
At a later date, during 1950/60, a more in-depth intervention was conducted by Fernando Mardel focusing in particular on the wooden supports. Two paintings had the upper corners gilded, making them different from the rest of the group . There was no doubt that they had been repainted at some stage, probably to imitate the original frame. In fact, all the remaining pictures had the upper corners painted, but not gilded; they presented a continuity of the drawing composition in the upper corners, as is visible in the paintings, Meeting of St. Anne and St. Joachim and Flight into Egypt (Figure 8).
Radiographic examination and sampling of the upper corners were performed for a study of authorship attribution . The results showed that the corner paintings painted directly on the wooden support were not original. Originally, the corners would not have been painted and had been covered by their frames, which had disappeared since then (Figure 9).
The pigments of the various layers on the upper corners were analyzed and the results confirmed them as additions [13, 14]. Not only are the pigments different but also the ground layer is gypsum and not chalk such as was found below the remaining paint layers (Figure 10).
Left to right:
Figure 8. Before the intervention: a) Virgin’s marriage; b) Presentation of the Virgin in the Temple; c) Meeting of St. Joaquim and Sta. Ana; d) Flight into Egypt. Photos by José Pessoa, DGPC.
Figure 9. Before the intervention a) Meeting of S. Joaquim and Sta. Ana; b) and c) the same detail of visible light and X-ray. Photos and X-Ray performed by José Pessoa, DGPC.
Figure 10. Cross-section from Meeting of St. Anne and St. Joachim, in the upper right corner, for identification of pigments and ground layer. Analysis by Ana Mesquita e Carmo, DGPC.
A decision was reached by the project team to remove the gilded corners on the two paintings in order to become identical to the other paintings. The removal of the painted corners on the other paintings leaving the plain wood corners was taken into consideration [2-15]. But given that some paintings had their edges cut and that the upper corners were are all uneven, this action could lead to a large aesthetic imbalance, and would delete traces of historically adopted solutions in different periods. Thus, for the sake of the pictorial group harmony in the museum context, it was decided to leave the painted false corners and mount them in their non-original mounting. After lifting the gilded corners, different types of integration techniques were used in these two paintings: The marriage of the Virgin and The Presentation of the Virgin, where the drawing was missing. The lifting of the gilded surface layer left lacunae visible (Figures 11-13).
Left to right:
Figure 11. Virgin's Marriage, before intervention. Photo by José Pessoa, DGPC.
Figure 12. Virgin's Marriage, after intervention. Photo by José Pessoa, DGPC.
Figure 13. Virgin's Marriage, repaint removal and retouching options. Photos by Mercês Lorena, DGPC.
5. Altarpiece from the Cathedral of Funchal (c.1515/17)
This altarpiece has the inestimable value of a work from the early 16th century, offered by King Manuel I to the city of Funchal, and which remains in its original location, largely untouched to the present day, being very unusual in Portugal. So far no document has identified the author(s) of this work set or its date. The construction of the cathedral began in 1493 and obtaining its license in 1497 from King Manuel I .
The altarpiece of Funchal fills the entire back wall of the church, behind the old altar. The altarpiece is subdivided horizontally in three levels by carved and gilded gothic wooden sections. A total of 12 panel paintings, all of equal height are placed in the wooden altar structure.
On the lower section, from left to right, are represented four Eucharistic scenes: Abraham and Melchizedek, the Last Supper, the Mass of St. Gregory and Manna from Heaven. In the middle section, four scenes related to The life of the Virgin: Annunciation, Nativity, Pentecost and the Assumption of the Virgin. On the top section there are four scenes depicting the Passion of Christ: Christ in the Garden, Christ on the Way to Calvary, Descent from the Cross, and the Resurrection.
At the center of the altarpiece, in probably non-original niches, are placed at the bottom the tabernacle, a sculpture of the Assumption of the Virgin, and at the top, a painting on canvas depicting the figure of Christ (Figure 14).
Left to right:
Figure 14. Altarpiece from Funchal’s Cathedral before the intervention of 2013/14: 1 - Abraham and Melchizedek, Last Supper, Mass of St. Gregory, Catch Manna; 2 - The Annunciation, Nativity, Pentecost, Assumption of the Virgin; 3 - Christ in the Garden, Christ the Way to Calvary, Descent from the Cross, Resurrection of Christ. Photo by Luís Piorro, DGPC.
Figure 15. Four paintings by Fernando Mardel intervened in the 40s in José de Figueiredo Institute, Lisbon: Abraham and Melchizedek, Catch Manna, Annunciation, Christ in the Garden. Photos by Luís Piorro, DGPC.
Figure 16. Six paintings were intervened in-situ on an unknown date: Christ the Way to Calvary, Descent from the Cross, Resurrection, Nativity, Pentecost, and Assumption of the Virgin. Photos by Mercês Lorena, DGPC.
In 2011, a protocol was signed between the following entities for the conservation and restoration intervention of the altarpiece from Funchal: the World Monument Fund, Portugal (WMF-P); the Regional Directorate of Cultural Affairs of Madeira (DRAC); the General Directorate for Cultural Heritage (DGPC) of Portugal; and the HERCULES Laboratory, University of Évora. The Laboratory José Figueiredo (LJF-DGPC) coordinated the conservation and restoration intervention.
The first preliminary study highlighted the huge lack of pictorial unity of these paintings . This fact was due mainly to the different degrees of cleaning of the chromatic layers from the various restoration interventions undertaken previously.
Three different conservation situations were presented in the pictorial set:
a) A first group of four paintings restored in the 1940’s: Abraham and Melchizedek, Manna from Heaven, Annunciation and Christ in the garden;
b) A second group of six paintings held the greater accumulation of secular dirt: Nativity, Pentecost, Assumption of the Virgin, Christ on the way to Calvary, Descent from the Cross, and Resurrection;
c) A third group of two paintings were repainted: The Last Supper and The Mass of St. Gregory.
Left to right:
Figure 17. Two paintings were intervened in-situ on an unknown date with total repaints: a) Last Supper, general and detail of the repaint; b) Mass of St. Gregory, general and detail of the total repaint. Photos by Luís Piorro, DGPC.
Figure 18. Christ in the Garden with the upper top with gold bow, a result of the intervention in 1940 IJF. Details of the intervention of 2013/14 on lifting the golden repaint. Photos by Luís Piorro (general) and Mercês Lorena (details), DGPC.
Figure 19. Christ on the way to Calvary. Details of the intervention of 2013/14 with the removal of non-original gilded carvings. Photos by Luís Piorro (general) and Mercês Lorena (details), DGPC.
After the condition survey and the grouping phase, the following issues were taken into account:
1. The four paintings intervened by Mardel in the 1940’s had been evacuated and transported to Lisbon. The wooden support had been consolidated and the boards joined through dovetails. The painted surfaces were cleaned by removing dirt and varnish, gaps were leveled and filled, possibly with a kaolin filling paste, and were retouched with oil, as was customary at the time (Figure 15).
2. Six paintings representing scenes of the Christ and the Virgin presented a great amount of debris, namely dust, wax, paint drops and oil substances that were applied in later interventions. These six paintings, before the intervention of 2013/14, were in worse condition with some open joints in the oak panels, especially due to dust and stones that fell from the back of the altarpiece. It was considered that the two paintings that were in the worst condition were the paintings on the right hand side of the top section of the altarpiece, Descent from the Cross and Resurrection, perhaps because they had had more contact with water leaks from the roof (Figure 16).
3. The two paintings that were totally repainted, Last Supper and the Mass of St. Gregory, present thick and uneven brushstrokes, causing a rough effect that is very diverse from the remaining paintings. They were covered with a large quantity of dirt and soot, probably by being closest to the torches or candle chandeliers (Figure 17).
The upper tops of four paintings that were intervened in the 1940s had a golden arch repainted over the original blue . In the 2013/14 intervention it was found that the original layer was scratched to receive the gilded layer preparation. Due to the difficulty of the conservation intervention in-situ using scaffoldings, it was decided to remove only the gilded layer that was not covered by the carved wood sections (Figure 18).
After removal of the carved wood in the remaining panel paintings, the existence of a light blue over an original dark blue was detected, corresponding to a repaint. In the original dark blue area, it was possible to identify the marks of the lost original carved wood baldachin (Figure 19).
Considering the difficulty in removing the total repaint, it was decided to apply on each painting a thin painted screwed board with the tone of the original dark blue that would be visible under the hollowed gilded relief carved wood. This was a practical solution to keep the historical traces of different interventions and reduce the excessive wear that such an intervention subjects the painting to (Figure 20).
The decision on the most appropriate type of integration, on the solution that less compromises the original artistic values, or its interpretation, without interfering in the final aesthetical reading, is not an easy one. That is why it is so problematic and complex to integrate lacunae, especially if they are large.
When the cleaning stage began on the pictorial panels in 2013, the Last Supper and the Mass of St. Gregory, showed a large aesthetic and technical disparity from the remaining set of paintings, which could even lead to erroneous historic or artistic interpretations. The decision criteria relating to the removal of the old interventions were analyzed and well justified. Removing the repaints concealing all or parts of the original painting were in this case largely justified by stratigraphic and radiographic examination. It was found that much of the original painting, similar to the remaining paintings of the altarpiece, were still present underneath (Figures 21-23).
Having evaluated the degree of difficulty in removing the repaints, it was concluded that it would be possible for them to be removed without any damage to the underlying painting layer. The project team considered that the aesthetic continuity of the paintings would always be an asset for the altarpiece appearance, which requires a complete and uninterrupted reading of all the depicted scenes, including the faces of Christ and flushes identical in all scenes (Figures 24).
Left to right:
Figure 20. Christ in the Garden (left) and Christ the Way to Calvary (right), after intervention in 2014 to apply on each painting a thin painted screwed board with the tone of the original dark blue that would be visible under the hollowed gilded relief carved wood. Photos by Mercês Lorena, DGPC.
Figure 21. Mass of St. Gregory: 1- detail before intervention; 2- detail with UV 3detail with X-ray; 4 / 5 - cross sections with layers of repaint; 6 – detail after the intervention. Photos: UV and X-Ray performed by Luis Piorro, DGPC; cross-sections by Ana Margarida Cardoso HERCULES).
Figure 22. Last Supper, face detail of christ before the intervention, normal light (left) and X-ray (right). Photos by Luis Piorro, DGPC.
Figure 23. Last supper: face detail of Christ after the intervention. Photo by Mercês Lorena, DGPC.
Figure 24 Resurrection of Christ: face detail of Christ after the intervention. Photo by Mercês Lorena, DGPC.
6. The Decision-Making Process
The methodology used for each of the interventions reported here was not unique. The dialogue between the technical conservation and restoration team and the owner or curator of the work of art was crucial and necessary to find the best solution for each decision.
In the case of the altarpiece of the Virgin of Sorrows, the decision of leaving the old repainting and fitted fragment at the bottom of the panel was decided between the LJF conservation team of LJF and the MNAA painting collection curator.
In the other two retables, the concern was to involve all the stakeholders in the decision-making process. The concern was to set up a large pluridisciplinary team to ensure that all alternatives were considered. In the case of the Life of the Virgin from the Cathedral of Évora, the team set up was the following six conservation technicians, five science technicians from the laboratory, two photographers and the director of the museum of Évora in his roles of art historian and owner of the object. All decisions were taken by the group upon the recommendation of the conservation-restoration team.
In the case of the retable of the Cathedral of Funchal, all options were debated and tested in situ. Alternatives and tests were performed by the conservation team headed by the Painting coordinator from LJF. In each stage, for every major decision, a presentation was made to all stakeholders: DRAC (Madeira Regional Directorate for Culture), the owner of the retable; the chapter of the cathedral of Funchal; and the patron of the restoration project, WMF-P (World Monument Fund - Portugal).
The patron WMF brought in a team of foreign and national specialists to control and oversee the process. The team involved six art historians, four laboratory scientists, a conservator-restorer and, last but not least DRAC Directors and the scientific coordinator (HERCULES Laboratory).
Meetings involved major presentations of image and photographic testimonial elements, the status of the works and the proposals for debate for every major step and decision. A key element for the decision was the analysis and interpretation of laboratory results which introduced substantially more objectivity in the debate. Therefore, consensus was reached without much hassle.
And this is the role of the conservator coordinator (who does not have a formal decision power): to gather analytical and documentation data, identify alternatives, and make the final conservation proposal with its rationale, for the scrutiny of a broad panel of other fields’ specialists. The rationality and objectivity of the process makes the consensus easier than in the past where aesthetic and painting technique considerations were the fundamental basis of the decisions.
The type of integration employed should be considered, debated, and the various alternatives evaluated in order to find the requested balances, including the collective aesthetic reading of the altarpiece. In fact, there are several types of integration, or more precisely, of retouching. This term fell into disuse in the conservation language, mostly due to the will of breaking with the past that often confused retouching with repainting.
The retouching is the chromatic integration without invention of missing areas. It is a commitment to historical honesty with an aesthetic requirement, which should leave, when possible, some of the changes perceptible, just easing them. Retouching is considered the most abstract, less objective step in the whole process of intervention of a painting, and yet is the most difficult to establish delimitation criteria. In reality, it is actually the least significant conservation stage, particularly today, when reversibility of materials is the norm for the preservation of the object itself.
In these paper, three examples of altarpiece interventions were presented. The solutions retained and executed were different depending on the overall requirement for the conservation and preservation of the entire altarpiece. In each of these cases, we followed the same methodological path to decide the appropriate intervention. The initial detailed diagnostic is fundamental. The conservation survey seeks to research existing historical documentation, gather analytical data from various complementary techniques and laboratory tests and get to the correct interpretation of the material so as to make informed decisions on the intervention to be executed. To find valid options within the new visual equilibrium that the entire altarpiece will have, without generating any damage to either structure or materials is a complex process. Careful planning of the execution according to the work conditions that can be feasible, especially for those in-situ (scaffolding) or in the conservation studio (museum works); it is necessary to always consider the artworks as part of a whole and not as individual objects when selecting the solution. Whenever possible, it is recommended to keep a thorough documentation of the conservation intervention process and the reasoning behind the options taken.
A final note, we must remember that each integration is a compromise between historical honesty and aesthetic requirements. In the cases presented, integration decisions were taken weighing up several factors; the broad reading of the whole altarpiece project, the execution conditions of the plan, the definition of the criteria for the intervention so as to achieve the final goal, which was to highlight the homogeneity of the altarpiece and preserve it for future historical research including those of authorship.
I am grateful to my service, Direcção Geral do Património Cultural (DGPC) for the opportunity to work on these retable interventions and to the Foundation for Science and Technology for funding the tuition fees of my PHD in Art History at the University of Évora under the supervision of José Alberto Gomes Machado e José António Mirão. I would also like to thank all my colleagues who participated with me in the intervention of these works over several years. And thanks to Francisca Figueira and António Taquenho, in particular, for the support in the translation of this article.
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General Directorate of Cultural Heritage