Conference paper

Piqué, Francesca; Moretti, Patrizia; Villiger, Verena; Python, Fabiene; James, Julian:

The 16th Century Wall Painting Cycle recently Discovered in the Town Hall of the City of Fribourg (Switzerland): Multidisciplinary Conservation Approach

The Town Hall of Fribourg, today the seat of the cantonal parliament, will celebrate its 500th anniversary in 2022. During the current renovation and restoration work, a splendid cycle of painted and sculpted decorations from the years 1511-1531 was discovered behind 18th century wood pannelling in the former Salle du Petit Conseil. Until the end of the 18th century, this room was the center of political, judicial and administrative power in the city-state. Alongside Gothic sculptural elements, painted ornaments in the form of candelabras and hybrid beings - herald the Renaissance in Fribourg.
The wall paintings, including a large frieze in chiaroscuro on a green background, bears the date 1531 and runs along the western wall of the room. They illustrate the story of Susanna saved by Daniel (OT, Dn 13), an iconography particularly appropriate to a courtroom where warnings against false testimony were addressed as much to the accused as to the judges.
The painted surfaces were heavily soiled and disfigured by projections of plaster from the construction of a new ceiling in 1775. Initial cleaning tests revealed a painting of exceptionally high quality, with highlights in metal leaf, fine modeling and a deep blue background. A campaign of non-invasive investigations (technical photography, portable microscopy and XRF and FT-IR spectrometry) was launched to understand the painting technique and to inform and support the conservation strategy. Non-invasive investigations revealed the presence of calcium carbonate for the white ground layer, azurite for the blue background, lead white and lead-tin yellow for the fine cross-hatching, a copper-based green for the figures in chiaroscuro and gold leaf for selected highlights. The possible detection of a proteinaceous material and the weak contribution of a lipid component may be associated with the use of an egg tempera as paint binder. Based on these results a few representative samples were collected to further characterize the painting technique in terms of stratigraphy and chemical composition of the pigments and binder used. The information obtained, combined with extensive visual examination numerous tests, were used to develop a conservation intervention with materials and methods safe for the original paintings. The conservators chose a dry-cleaning method using synthetic rubber erasers which were able to achieve excellent dirt removal. Adjacent to the wall paintings is an iron door, originally guarding the war treasury and bearing the same chiaroscuro decoration, the cleaning and devarnishing of which gave stunning results.
The presentation will provide a thorough description of the painting and subject matter, the role of non-invasive investigations in support of decisions regarding direct intervention and the challenge of the long-term conservation. Although it has been decided to privilege the important and coherent 18th century finishes in the room, the paintings will remain easily accessible and will benefit from an extensive photographic and 3D documentation.
Contact: francesca.pique@supsi.ch; Fabien.Python.sbc@fr.ch

Francesca Piqué, Conservator-restorer and chemist, Conservation Restoration unit of the Institute of Materials and Construction, Department of Environment Construction and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI_DACD_IMC), Mendrisio, Switzerland
Patrizia Moretti, Conservation scientist, Conservation Restoration unit (SUPSI_DACD_IMC)
Verena Villiger, Art historian, former director of the Art and History Museum Fribourg
Fabien Python, Art historian, Service des Biens Culturels SBC. Planche-Supérieure 3 1700 Fribourg
Julian James, Conservator-restorer, Estavayer-le-lac