The gilded bronze eagles that stand up high on the summit of the ciborium in the Abbazia of San Miniato al Monte, in Florence (Figure 1a), are an exquisite example of Italian Renaissance sculpture. Commissioned by Piero di Cosimo de Medici, the two eagles representing the ancient Guild of Calimala were cast and decorated by Maso di Bartolomeo in 1449. In the framework of the celebrations for the millenary of the Abbazia held in 2018, an extensive restoration project started for conservative and aesthetic purposes. Supported by the Friends of Florence Fundation, the restoration involved all the artifacts in the ciborium, including the eagles, to uncover the original gilded surfaces affected by corrosion products, aged coatings and disfiguring deposits. A diagnostic project was set up to characterize the state of conservation, the materials used and the artistic technique. Non-invasive techniques were used and integrated by micro-invasive analyses, such as X-ray fluorescence (XRF) and Fourier-Transform Infrared (FT-IR) spectroscopy, X-Ray Diffraction (XRD), Scanning Electron Microscopy coupled with EDS probe (SEM-EDS), metallographic observation. The analyses were repeated through the cleaning steps performed with laser ablation and chemical products (Figure 1b). The results of the multi-analytical approach provided useful information for the intervention, confirming the use of oil gilding and revealing the presence of a partial polychromy, almost unusual in the XV century bronze statuary and initially hidden by the patina of time. Legs were originally painted with azurite, while the use of cinnabar imparted a vivid red colour to the tongue. A black paint containing mercury was found on eyes and nails. XRF revealed silver foil on the cushion, now tarnished, while fine details in gold were detected on the rope.
Unveiling the gilded eagles by Maso di Bartolomeo in the Abbazia of San Miniato al Monte, Firenze. Integrated approach for the restoration of polychrome bronze sculpture
B Salvadori;E Cantisani;
2019
Abstract
The gilded bronze eagles that stand up high on the summit of the ciborium in the Abbazia of San Miniato al Monte, in Florence (Figure 1a), are an exquisite example of Italian Renaissance sculpture. Commissioned by Piero di Cosimo de Medici, the two eagles representing the ancient Guild of Calimala were cast and decorated by Maso di Bartolomeo in 1449. In the framework of the celebrations for the millenary of the Abbazia held in 2018, an extensive restoration project started for conservative and aesthetic purposes. Supported by the Friends of Florence Fundation, the restoration involved all the artifacts in the ciborium, including the eagles, to uncover the original gilded surfaces affected by corrosion products, aged coatings and disfiguring deposits. A diagnostic project was set up to characterize the state of conservation, the materials used and the artistic technique. Non-invasive techniques were used and integrated by micro-invasive analyses, such as X-ray fluorescence (XRF) and Fourier-Transform Infrared (FT-IR) spectroscopy, X-Ray Diffraction (XRD), Scanning Electron Microscopy coupled with EDS probe (SEM-EDS), metallographic observation. The analyses were repeated through the cleaning steps performed with laser ablation and chemical products (Figure 1b). The results of the multi-analytical approach provided useful information for the intervention, confirming the use of oil gilding and revealing the presence of a partial polychromy, almost unusual in the XV century bronze statuary and initially hidden by the patina of time. Legs were originally painted with azurite, while the use of cinnabar imparted a vivid red colour to the tongue. A black paint containing mercury was found on eyes and nails. XRF revealed silver foil on the cushion, now tarnished, while fine details in gold were detected on the rope.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
