Archaeometry and conservation of gilded bronzes from the city of Qalat Rabah (Calatrava La Vieja) Spain

In the context of the archaeological excavations carried out in the ancient city of Calatrava La Vieja, a number of gilded bronze objects was found. Consisting mainly of appliques and decorations for larger objects, they are of outstanding aesthetic and technical level, and characteristic of the different cultural phases of the city during the Middle Ages. The islamic city Qualat Rabah was founded in the Century VIII during the Omayad period; due to its strategic position between Cordoba and Toledo, it was held both by Christians and the Arabs several times until A.D. 1212, when it came into the kingdom of Castilla; since then its power decayed until the definitive abandonment in the Century XVI. The present work is focused on the study of the materials, the deterioration processes - related to the interaction of different metals - and the conservation-restoration methods. The fabrication technology, the composition of the alloys and the gilding technique were also investigated by combining different techniques such as radiography, SEM and XRF. Besides the optimisation of the restoration procedures, the research provided a better understanding of the corrosion processes and the manufacturing techniques of this type of gilded bronzes.