ELEMENTAL ANALYSES OF A GROUP OF GLAZED TERRACOTTA ANGELS FROM THE ITALIAN RENAISSANCE,AS A TOOL FOR THE RECONSTRUCTION OF A COMPLEX CONSERVATION HISTORY*

A group of Italian glazed terracotta sculptures, attributed to the della Robbia workshop of Florence, is partly displayed in the Louvre Museum. Analyses of the apparently homogeneous sculptures by techniques such as PIXE, SEM, ICP/AES and ICP/MS have identified differences in the materials used. The data provide a subdivision of the sculptures, which is compatible with what is known from historical documents and artistic considerations, and suggest a date for this ensemble at the end of the 15th century, when the della Robbia family was involved in the decoration of the San Frediano church in Florence.     

ARCHAEOMETRIC INVESTIGATIONS OF SGRAFFITO CERAMIC TILES (FIFTEENTH‐SIXTEENTH CENTURIES) RECOVERED FROM EXCAVATIONS IN UDINE (NORTH‐EAST ITALY)*

Most of the Renaissance sgraffito tiles excavated in Udine (Italy) constitute a homogeous group, the tile body having a CaO/MgO molar ratio ?= 3:2. They were produced using a dolomite‐ and calcite‐containing clay fired at 900–950°C. A small group of samples, with a lower firing temperature and a CaO/MgO ratio ?= 2:3, was probably produced in a different factory. Slip and transparent glaze, characterized by optical microscopy and inductively coupled plasma atomic emission spectrometry, are an illite‐rich clay and a lead silicate, respectively.     

A NEW SETTING FOR THE NORTHERN BORDER OF THE VENETI: METALLIC FINDS FROM THE VENETIC SITE OF MONTE CALVARIO,AURONZO DI CADORE*

In 2000 several bronze and lead objects were discovered at the Venetic‐Roman site (200 bc –ad 200) of Monte Calvario di Auronzo, in the Italian eastern Alps. They were mostly finished artefacts plus semi‐worked products. Analysis included SEM–EDS, EMPA, XRPD, TMS and AMS spectrometry. The compositional results of the finished artefacts suggest that the choice of the alloy had been made according to the decorative techniques to be used. A semi‐worked high‐leaded bronze object indicates the existence of a metallurgical production of cast artefacts at the site. TMS analyses of a lead ingot exclude local provenance, proving the existence of important trade routes.     

SPECTROSCOPIC INVESTIGATION OF RED STAINS AFFECTING THE CARRARA MARBLE FAÇADE OF THE CERTOSA OF PAVIA

The nature of the large red stains exhibited on the Carrara marble elements of the Certosa of Pavia façade was investigated by means of spectroscopic techniques and scanning electron microscopy. Although previous microbiological analysis has demonstrated the presence on the stone of a bacterial strain identified as Micrococcus roseus, that is capable of carotenoid production, it has been ascertained in the present study that an inorganic pigment, namely Pb₃O₄, is responsible for the observed coloration. On small green spots, the presence of photosynthetic micro-organisms has been demonstrated by microbiological analysis and confirmed by resonance Raman spectroscopy.     

ON THE EMBALMMENT OF S. FRANCESCO CARACCIOLO

The Italian saint Francesco Caracciolo died in June 1608 and his body was transported from Agnone in the Abruzzo region to the city of Naples, where he was interred. According to written sources, his body was embalmed, but the embalmment method is unknown. In the present work, four samples of the remains of S. Caracciolo have been analysed for traces of embalmment. No organic compounds usually used for embalmment were found using GC with MS detection. Only low background levels of As were measured using CV‐AAS (Cold Vapour Atomic Absorption Spectroscopy). In two samples analysed by CV‐AAS, however, very high concentrations of Hg (12.7 μg g^?1 and 4.9 μg g^?1) were measured, these being 100 to 1000 times more than the background Hg levels found in bone tissue of other medieval and Renaissance individuals. Two interpretations seem viable: (1) the high Hg levels are caused by embalmment using Hg‐containing compounds; (2) the excess Hg originates from a medical treatment that S. Caracciolo received in his youth, when he was cured of leprosy, or in connection with his illness just prior to his death. The case of excess Hg in the remains of S. Caracciolo has distinct parallels with those of other Renaissance burials.     

MICRO‐RAMAN SPECTROSCOPY CHARACTERIZATION OF DELLA ROBBIA GLAZES*

Micro‐Raman spectroscopy and the laser‐induced transformation technique were used for systematic study of five coloured glazes on Saint John the Baptist (29 inch tondo), a majolica terracotta relief attributed to Luca Della Robbia and on permanent exhibit in The John and Mable Ringling Museum of Art. We suggest that ions in a lead silicate matrix, called ‘lead ultramarine’, could contribute to the famous Della Robbia blue colour, in addition to the effect of Co atoms as suggested previously by Pappalardo et al. (2004 ). The original yellow glaze contains lead(II) antimonate. The green is a mixture of the yellow and blue pigments, the brown contains hematite, and the white glaze contains tin dioxide as an opacifier. The use of lead oxide as a main fluxing agent is confirmed by laser‐induced micro‐crystallization.     

THE ‘DELLA ROBBIA BLUE’: A CASE STUDY FOR THE USE OF COBALT PIGMENTS IN CERAMICS DURING THE ITALIAN RENAISSANCE*

The morphologies and elemental compositions of cobalt blue glazes are studied in 56 dated and undated terracotta sculptures from the Florentine della Robbia school. The data allow tracing of the pigments through correlations amongst elements that are known to be constituents of the cobalt minerals. The supply of such minerals from the Erzgebirge region in Renaissance times is compatible with our data. A substantial change in the materials is marked by the presence of arsenic and bismuth in the glaze, and by reduced amounts of iron and nickel just before 1520. We speculate that this is due to procedures introduced to industrialize the production of the blue pigment. The exploitation of different cobalt minerals in association with different production procedures may explain the variability of compositions that we observe in this unique ensemble.