The baptismal font of the Cathedral of Siena shines again after three years of restoration, an extraordinary masterpiece in marble, gilded bronze and enamelled copper created by Donatello, Jacopo della Quercia, Lorenzo Ghiberti and Giovanni di Turino.
The restoration is the result of a series of interventions, of a very high and innovative technical level, conducted by the personnel of the Opera della Metropolitana of Siena and by the highly specialized personnel of the Opificio delle Pietre Dure of Florence, led initially by the recently deceased Marco Ciatti and, subsequently by Emanuela Daffra. Under the high surveillance of the officials of the Superintendency of Archaeology, Fine Arts and Landscape for the provinces of Siena, Grosseto and Arezzo, first directed by Andrea Muzzi and, currently, by Gabriele Nannetti, the staff of the Opera and the Opificio, with the fruitful collaboration of restorers and university professors, took turns in the complex restoration of a work resulting from the brilliant expertise of the greatest artists of the first half of the fifteenth century: different but connected interventions which, once completed, restore a central place from a pastoral and liturgical and, at the same time, a true masterpiece of immeasurable beauty.
Positioned at the center of the architectural structure of the Baptistery, the baptismal font, built between 1417 and 1431, required very careful investigations and great skills in defining the restoration program. The gold was tarnished, the surfaces were affected by abrasions and the state of conservation of the stone material was also rather uneven, much worse in the lower register than in the upper part. To verify the statics of the architectural structure and the environmental parameters, two different in situ investigation campaigns were undertaken: ultrasonic measurements verified the presence of metal anchors inside the Source and geophysical investigations on the floor investigated the presence of voids or humidity fronts in the substrate archaeological. An in-depth diagnostic campaign preceded and accompanied the entire intervention with the first phases involving the dismantling of the bronze elements to adequately evaluate the state of conservation of the non-visible surfaces and intervene on areas with significant alterations, which otherwise would not have been accessible.
Thanks to the intervention it was possible to observe the creations of Giovanni di Turino (Birth of the Baptist panel, Predica del Battista panel and Virtù Prudenza panel) which proved to be the result of an ingenious assembly of portions cast separately.
The careful study of Donatello’s panel Banchetto di Erode has made it possible to identify the presence, in the past, of tie rods applied between the arches above the scene which must have amplified the perspective and realistic effect of the architecture depicted which offers three different spaces in succession.
The stone elements were restored on site in the construction site set up inside the Baptistery. If the disassembly was not simple, the reassembly was no different, as it involved the study and creation of new elements and fixing joints made specifically in order to readjust the positions of the incorrect stone architectural elements. The state of conservation and the need to make the non-visible parts of the tiles accessible for inspection over time has dictated the design of a support structure for the stone elements which allows access to the back of the bronzes without necessarily having to dismantle the blocks. marble.
