Donatello's bronze Doors return to Basilica of San Lorenzo in Florence after painstaking restoration

After careful and complex restoration work, the Door of the Martyrs and the Door of the Apostles made by Donatello between about 1440 and 1442 have been relocated to the Old Sacristy of the Basilica of San Lorenzo in Florence. The two restored bronze Doors were presented to the public this morning during an in-depth meeting dedicated to the new features that emerged during the restorations, followed by a visit to the Old Sacristy that allowed the public to admire them once again mounted in their original location.

The restoration was conducted by the Bronzes and Ancient Weapons Sector of the Opificio delle Pietre Dure, under the direction of Laura Speranza and Riccardo Gennaioli, and carried out by a team of specialized restorers (Stefania Agnoletti, Maria Baruffetti, Annalena Brini, Elisa Pucci, and Giovanni Rotondi of the OPD, with Nicola Salvioli and Saskia Giulietti). The first intervention concerned the Porta dei Martiri, presented in 2022 on the occasion of the exhibition Donatello. The Renaissance at Palazzo Strozzi, an event that marked a crucial moment in studies on the artist. The recovery of the Door of the Apostles, supported by Friends of Florence through a donation from Michael and Sandy Collins, began in June 2024 and was completed on October 1, 2025.

Commissioned by the Medici family, the two doors, each consisting of a pair of wings, represent one of the pinnacles of Donatello’s plastic research in the mature phase of his career. Made with the sophisticated technique of lost-wax casting, the four doors take the form of relief polyptychs set in a complex architectural frame of boulder, punctuated by Ionic columns supporting an entablature culminating in a triangular tympanum. Each casement features five large panels with pairs of saints. In the Door of the Martyrs (so called because of the presence of the palm branch, symbol of martyrdom) appear, among others, Stephen, Lawrence, Cosmas and Damian, protectors of the Medici. The Door of the Apostles depicts John the Baptist, the Fathers of the Church and the Evangelists. The panels are framed by elegant friezes adorned with rosettes, while the handles, which are not original, take the form of intertwined ropes.

Prior to the start of the restoration, and following the 3D scanning of the surfaces, the Scientific Laboratory of the Opificio delle Pietre Dure conducted an extensive diagnostic campaign. The analyses provided fundamental data to understand the state of conservation and to define targeted interventions that respect the original material, as well as offering new elements on the execution technique.

The doors, about 4-5 centimeters thick (with greater thickness at the top to facilitate rotation), appear to have been cast in one piece, with no visible mechanical hooks, not even for the large hinges. The quality of the casting is extraordinary: the backgrounds of the panels are polished with extreme care, while the robes and hair of the saints have very fine punching that generates refined chiaroscuro effects. Before the restoration, however, the surfaces appeared flattened and smothered by substantial deposits and brown oily-waxy substances that had stratified over time. In the lower parts, greenish color changes were evident due to the degradation of waxes and bronze corrosion products, with thick concretions impairing the legibility of the modeling.

The operations began with a preliminary dusting, followed by steam washing supported by the use of swabs and brushes, to remove waxy or oily deposits and residues from previous maintenance. Cleaning continued with mixtures of different solvents and with a thorough refinishing of the door fronts, including by cryogenic sandblasting (a technique that employs small ice pellets projected by compressed air) that was particularly effective in freeing the minute workmanship of friezes and figures. On the backs of the doors, the intervention was carefully modulated, preserving traces of ancient patination and residues of the casting earths in the unworked areas. Thicker concretions along edges and profiles of the doors were removed with vibro-etching. At the conclusion of the restoration, the surfaces were protected with microcrystalline waxes.

Donatello's bronze Doors return to Basilica of San Lorenzo in Florence after painstaking restoration

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