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Wall Paintings in the Château de Germolles: an interdisciplinary project for the rediscovery of a unique fourteenth-century century decoration

Christian Degrigny and Francesca Piqué with contributions from Marco Cucchi, Vincent Detalle, Jean-Philippe Farrugia, Gaëtan Le Goïc, Alamin Mansouri, Dominique Martos-Levif, Frédéric Mérienne, Aurélie Mounier, Anthony Pamart, Cristina Tedeschi, Jean-Marc Vallet and Stefanie Wefers

ABSTRACT

The Germolles case study aimed to examine and document the wall paintings in the Château de Germolles. Situated in Burgundy, France, Germolles is the best preserved residence of the Dukes of Burgundy. It was owned by Margaret of Flanders, wife of Philip the Bold, Duke of Burgundy and brother of Charles V, King of France. Built between 1380 and 1400, it shows the interest of French dukes in rural life and foreshadows the French Renaissance. Today it is in private hands but is open to visitors all year long. The Château de Germolles was listed as monument of national importance in 1989.

The medieval wall decoration of the Château de Germolles was rediscovered under the 19th century plasters during the World War II. The walls of the ducal apartments are painted in green possibly to suggest green fields. The initials of the princes, “P” for Philip and “M” for Margaret, are applied in-between flowers — thistles, roses or marguerites. Medieval accounts of the Château provide a detailed list of the materials acquired to make the mural decoration, but this list is incongruous when compared with the current appearance of the paintings. The discrepancy between the archival and material evidence, but also the need to understand the complexity of the painting technique used were the main motivations for undertaking the case study described in this chapter. Imaging alongside more traditional examination techniques were utilized to record and document the mural decoration. The objectives of the case study were to:

  • Distinguish the original material from those applied during restoration;
  • Identify and analyze the original materials making the paintings;
  • Understand the medieval painting technique used;
  • Correlate the material listed in the archives with those identified in the paintings;
  • Assess the condition of paintings and stabilization requirements;
  • Find a sustainable solution for the management of the vast amount of the various types of data collected.

Orthophotographs of the mural decoration were produced and used throughout the study as basemaps for documenting the data produced by all the examinations. IR thermography was applied to assess the nature of the underlying wall structure, the stability of the plaster, and its possible detachment. A concurrent macro and micro photographic survey using visible light and UV/IR radiation allowed to appreciate the degree of originality of this mural decoration and to reveal residues of elaborated metallic foil decorating the walls. These metallic decorations were further investigated using highlight-reflectance transformation imaging (H-RTI) and structured light imaging (SLI). Analysis using X-ray fluorescence has identified gold and tin while visual examination revealed that the decoration comprised gilded tin foil (a material listed in the archives). Laser-induced breakdown spectroscopy (LIBS), using in-depth analyses through the multiplication of measurements in the same point, provided further information about the composition of the original and the restoration materials in the paintings. In parallel, a colorimetry campaign allowed to document their color.

These investigations offered valuable insights into the materials and the painting technique used. The white “P” and “M” letters in the dressing-room of Countess of Nevers, daughter-in-law of Margaret of Flanders, where most investigations were carried out, were applied by stenciling and display arabesques embellishment on the “P” which are missing in the letters ‘M’. The thistles were originally made of green tin foils partly or entirely gilded. Thin black paint lines were applied over the gold to create a relief effect. The examination has confirmed the use of large quantities of green tin foils at Germolles, as indicated in the medieval records. Only tiny remains of this sophisticated decoration are visible, but more survive in areas still covered by 19th century plaster. It was also necessary to investigate their stability and to determine their need for consolidation. This work has been the subject of a Master thesis at the University of Applied Sciences and Arts of Italian Switzerland (SUPSI) in Lugano.

To improve visitor experience, based on the information gained in the course of this study, a 3D virtual representation of the original decoration is currently proposed to the public visiting the Château de Germolles.

The work described in this chapter was carried out by experts from French, Swiss, Italian, German and Belgian institutions. It was partly funded by the Regional Direction of Cultural Affairs (DRAC) in Burgundy, while the COST Action TD1201, Colour and Space in Cultural Heritage (COSCH) provided scientific and technical support through 6 Short-Term Scientific Missions and experts meetings.

Keywords: Château de Germolles, dukes of Burgundy, Middle Ages, wall paintings, tin leaf decoration, spatial and spectral imaging techniques, COSCH

FIGURES

figure-1Figure 1. Bird’s eye view of the Germolles estate from north-west. The white arrow indicates the location of the room studied (dn) on the main building. The entrance gate is visible in the bottom left. The château was originally fully enclosed. Photo: Alain Rodrigue, 2007

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Figure 2. Details of wall paintings after conservation 1989–95 (a) in the dressing room of the Countess of Nevers; the red and blue dashed lines show the repetitiveness of geometrical pattern (b) in the dressing room of Margaret of Flanders, (c) Floor titles reproduce the floral decoration of the walls. Photos (a) and (b) Francesca Piqué, 2013 (c) Château de Germolles, 2008

figure-3Figure 3. Orthophotograph of the west wall of room dn. The profiles of letters P and M marked in white. The details of letter “P” circled in white are shown in figures 4 and 5. Photo: Julien Guery, 2014; the outlines Château de Germolles, 2016

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Figure 4. VIS and IR (approx. 830–1000 nm) photographic images of the letter P highlighted in figure 3. Arabesques in the lower part of the letter P are indicated in the VIS image. They seem to disappear in the IR image. Photos: Francesca Piqué, 2016

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Figure 5. Hyperspectral Imaging (recorded at 1000 nm) of the lower part of letter P, shown in figure 4. The white dotted line shows the original profile of the letter while the red dotted line in the RGB picture shows the profile of the embellished letter. Photos: Aurélie Mounier, 2016

figure-6Figure 6. Micro observation of a letter M under a Dinolite® microscope. White ground  (2), yellow (3) and white (4) paint layers. Photo: Nutsa Papiashvili, 2015

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Figure 7. Macro (a) to micro (b) observation of a thistle under a Dinolite® microscope. The stratigraphy comprises the underlayers (preparation and yellow layers, the green background (4) and the finishing metallic layers (5 to 9). Photos: Nutsa Papiashvili, 2015

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Figure 8. Cross-section of a fragment from a thistle, observed in visible light under an optical microscope. The identification of the material was carried out by combining (a) FTIR and SEM-EDS analyses; (b) Elemental mapping of the area in the red, dashed rectangular. Photos: Francesca Piqué, Dominique Martos-Levif and Stephan Ramseyer, 2015

figure-9Figure 9. Micro-photography of a gold leaf from a thistle in the upper parts of room dn, showing traces of a black glaze or paint layer. Photo: Francesca Piqué, 2014

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Figure 10. H-RTI snapshots under different illumination angles. Gold remains are evident in image (a) but not so much the stratigraphy of layers. The reverse is observed in (b), when the surface is illuminated from the opposite direction. Photos: Gaëtan Le Goïc, Alamin Mansouri and Château de Germolles, 2015

figure-11Figure 11. Representation of the steps in the historic process of decorating the dressing-room of the Countess of Nevers with murals. Photo: Château de Germolles, 2016

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Figure 12. (a) Alteration of lead white to achieve a shadow effect, observed on the edges of a P letter; (b) details of repainting (indicated by white arrows) the same P, applied in the course of the conservation campaign of 1989–95. Photos: Château de Germolles, 2015

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Figure 13. (a) Graphical representation through IRT of areas of detachment in the north wall of room dn, photo Cristina Tedeschi and Marco Cucchi; (b) Representation (overlaid onto an IR image) of similar areas, in blue, as recorded by tactile assessment (knocking method). Photo: Nutsa Papiashvili, 2015

figure-14Figure 14. Tie points between the point cloud of the south wall of room dn and a technical picture of a P in the same wall. Photos: Anthony Pamart, 2015 and Francesca Piqué, 2013

figure-15Figure 15. Snapshot from the SIVT application tested on Germolles case study data. The rectified and registered IR image of the “P” (red arrow) is displayed on top of the ortho-photography of room dn south wall, photos Wefers and Reich, 2016 and Piqué, 2013

figure-16Figure 16. Composite visualization of the actual decoration (left) transitioning to the virtual representation (right). Photos: Dorian Masson, 2016

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