Presentation of the COSCH Germolles Case Study to the Ferrara Salone del Restauro

On Friday, 8th May 2015, Dr Christian Degrigny of the Haute Ecole Arc Conservation-restauration (HE-Arc CR) in Neuchâtel and Professor Francesca Piqué of the University of Applied Sciences and Arts of Southern Switzerland (SUPSI) in Lugano, presented the COSCH Germolles case study to the Ferrara Salone del Restauro.

The speakers were invited by the Swiss Conservation-restauration Campus (Swiss CRC) —an association of four Swiss conservation schools. The talk was an opportunity to show an audience of conservation professionals how two Swiss institutions, namely HE-Arc CR and SUPSI, collaborate on a European project.

Photo © Regis Bertholon.

The Germolles case study aims to record anew the wall paintings of Germolles. Situated in Burgundy, France, the Château de 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 environments. Such a pastoral spirit, although interrupted by the second part of the Hundred Years' War with England, laid the foundation for the French Renaissance.

The medieval wall decoration of the Château de Germolles was rediscovered under the 19th-century plasters during World War II. Since then it has been listed and partly restored. Medieval accounting notes of the Château record the materials acquired to make the mural decoration, but they do not seem to match the composition of the existing paintings. This interesting mismatch between the archival and material evidence, and the complexity of the painting technique used, were the reasons for setting up the Germolles case study; and to use imaging techniques, alongside more traditional examination techniques, to record and document further the mural decoration.

Dr Christian Degrigny is a co-manager of the Château de Germolles, and a Swiss delegate to COSCH Action. He leads the COSCH Working Group 3 on the analysis and restoration of surfaces of cultural heritage objects. Working in partnership with several French laboratories, he first applied for funding to the Regional Direction of Cultural Affairs (DRAC) in Burgundy to carry out an additional analysis not related to imaging techniques. The application was approved in 2013.

At the same time, Professor Francesca Piqué was funded by COSCH to carry out her first Short Term Scientific Mission (STSM) on preliminary surveying the Germolles wall paintings using macro and micro visible light and UV/IR radiations, during which metallic remains were discovered. These were further investigated using highlight-reflectance transformation imaging (H-RTI) and structured light imaging (SLI), but it was only during her second STSM at Germolles that Francesca Piqué was able to determine the nature of the metallic remains. Using X-ray fluorescence she established that they consisted of gilded tin. In parallel, a colorimetry campaign enabled the assessment of the condition of the paintings.

Additional documentation and analytical work were carried out by the French partners in the project: the Captair company and the Research Laboratory of Historical Monuments (LRMH). Captair performed orthophotographies of the mural decoration. These will be used as basemaps to document all the examinations already carried out and those that will be performed in the future. IR thermography was tested by LRMH to assess the possible detachment of the wall paintings from the walls. The laser-induced breakdown spectroscopy (LIBS) provided further information both on the restored and original parts of the paintings, using in-depth analyses through the multiplication of shots.

All this work was the starting point for the Germolles case study. The kick-off meeting was held at the Château de Germolles in January 2015. An additional analysis of a detached fragment of the metallic decoration has been performed since. It allowed to determine their full stratigraphy.

Thanks to these preliminary investigations, we now know that the walls of the ducal apartments were painted in green to suggest fields. In some rooms, "P" and/or "M" letters were applied on top. These initials were separated by flowers — thistles, roses or marguerites. All flowers are symbolic. Thistles speak of fidelity or protection; roses are referring to Virgin Mary, while closed marguerites refer to the Duchess and her young age.

The figure below shows a detail of decoration of the bedroom of the Countess of Nevers (the daughter-in-law of Margaret of Flanders): the letters in white, with shadow effects as well as arabesques on the "P", in praise of Philip the Bold. The thistles were originally made of tin foils painted in green. They were gilded, although it is not known whether the whole surface of tin foils, or only parts of, were gilt. The gold was further decorated with black glazes to create a relief effect. The black effect of the thistles that is visible today is due to the mordant, used to fix the metallic foils to the wall. Only tiny metallic remains have been observed on top. These results confirm the use of large quantities of green tin foils at Germolles, in accordance with the medieval records.

Image © Francesca Piqué

More work has to be done to determine the degree of originality of this mural decoration and understand the way metallic foils were applied onto the floral motifs. As only the remains have survived, it is necessary to investigate their stability and consolidate them, if needed. This work will be the subject of a master thesis of a SUPSI student in 2015.

The talk given in Ferrara covered in detail the work that was carried out, which has been made possible through the complementary financial support of DRAC-Burgundy and COSCH, and through the contributions from different partners involved. Many Italian conservation professionals are not familiar with the way COST works. This presentation of the Germolles case study was therefore a good way of indicating how conservation professionals may get involved in a COST action.

For more information feel free to contact Christian Degrigny, <Christian.Degrigny@he-arc.ch>

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