Orsanmichele's San Marco, an early work by Donatello, restored

The restoration of San Marco, a marble sculpture by Donatello that belongs to the collection of the Orsanmichele Museum, has been completed. The intervention was made possible thanks to the collaboration between the Bargello Museums and theOpificio delle Pietre Dure and thanks to the financial support of the Friends of Florence association. The restored statue, a youthful masterpiece by Donatello (the artist sculpted it when he was only 25 years old, in 1411) and a founding work of the Italian Renaissance, is presented a few days before the museum reopens to the public, scheduled for June 1.

The restoration was carried out under the scientific supervision of Matteo Ceriana, former curator of the Orsanmichele Museum, and Riccardo Gennaioli, director of the Restoration Sector for Stone Materials of the Opificio delle Pietre Dure, with the collaboration of Francesca de Luca and Benedetta Matucci, and with the advice of a technical-scientific commission composed of Lorenzo Lazzarini (IUAV), Marisa Laurenzi Tabasso (Central Institute for Restoration) and Daniela Pinna (University of Bologna).

Withdrawn in 1977 from its location in the first niche on the south side of the patronage of the Linaioli e Rigattieri and placed on the second floor of the Orsanmichele Complex, the work constitutes the first Renaissance masterpiece of the cycle to be restored, from 1984 to 1986, by the Opificio delle Pietre Dure. On that occasion the bronze-colored patination, made after 1789 with the intention of matching the marble statues to the color of the other metal ones, was removed. With the first removal work conducted by the Opificio, the flowing naturalness of the modeling of St. Mark was recovered, as well as faint traces of gilding in the edges of the robe, on the cushion under the feet, on the Gospel blanket, in the sandals, and in the beard and hair. When the restoration was completed, it was decided to permanently remove the work from the exterior, with a cast being made in 1990, again by the Opificio.

More than 30 years later, the Opificio was again commissioned by the Bargello Museums Directorate to assess the state of conservation of the Renaissance statue and plan a new intervention. Prior to its admission inside the museum in 1977, the statue had been kept outdoors for nearly six centuries, and alteration phenomena typical of prolonged time spent outdoors could be seen in the stone material. However, all areas of decohesion were consolidated during the previous restoration and so far appear stable. The most obvious forms of alteration were concentrated at the surface level: the deposition of atmospheric particulate matter had darkened the appearance of the marble, and the presence of residual substances, due to the making of the cast, had altered its tone.

"In the spirit of Monuments Men, a number of U.S. nonprofit organizations have been established that are dedicated to raising funds in the United States for the preservation and restoration of Italian works of art, such as Friends of Florence, which over the past twenty-three years has played a key role in restoring Florence’s many beauties to their former glory," said U.S. Consul General in Florence, Ragini Gupta. “Millions of Americans have a special bond with the city of Florence, but this bond is strongly felt by the Friends of Florence Foundation, which has continued to demonstrate its love for the city even during the Covid-19 pandemic through the restoration of historic works of art.”

“I am particularly proud of this institutional collaboration,” said Paola D’Agostino, director of the Bargello Museums, "which confirms the excellence of the Opificio delle Pietre Dure in the field of restoration and conservation of the historic artistic heritage, as well as diagnostic testing. Donatello’s marble Saint Mark is a work misunderstood by the general public, just as little known is the amazing marble production of the most ingenious Florentine sculptor of the Renaissance. My greatest hope is that the monumental statue cycle of Orsanmichele, an absolute masterpiece of the Italian Renaissance, can once again be accessible to the widest possible number of people. The fundamental contribution of the Friends of Florence in this restoration project testifies to how much, in the international arena, it is perceived as a world heritage. Starting in June we will reopen the church and the Orsanmichele Museum twice a week, following current regulations and prescriptions due to the health emergency. I hope that with the help of all city, regional and national institutions we can create a fruitful collaboration that will lead in the near future to full enjoyment and accessibility of this extraordinary complex."

"After the 1986 restoration, which freed the sculpture from the heavy dark repainting, beginning the great project of recovering the entire sculptural cycle of Orsanmichele, the OPD has reintervened on the San Marco, Donatello’s youthful masterpiece, the first true autonomous sculpture after classical antiquity and thus one of the founding texts of the Renaissance," added Marco Ciatti, Superintendent of the Opificio delle Pietre Dure. “The technological developments between the two restorations made it possible to perfect the cleaning and make even more evident the profound classicism of the sculpture set on the polycletic ’ponderatio’ and the expression of the extraordinary head that seems to derive from that of an ancient philosopher. The restoration, directed by Riccardo Gennaioli, was carefully executed by Camilla Mancini and Franca Sorella and was accompanied by the scientific investigations of the Scientific Laboratory, carried out by Andrea Cagnini, Monica Galeotti and Simone Porcinai, which allowed a further deepening of the knowledge of the work.”

"The conservation project of Donatello’s San Marco, carried out together with the Bargello Museums and the Opificio delle Pietre Dure, has been a fundamental experience in gaining greater knowledge of the highest methods of analysis and restoration," explained Simonetta Brandolini d’Adda, president of Friends of Florence. “The results appear very evident when looking at this wonderful sculpture, but the knowledge gained is even more important in order to be able to preserve for the future and in an adequate way so many other works.”

In 1986 the Opificio delle Pietre Dure concluded the restoration of the San Marco, the first in a long series of interventions carried out on monumental sculptures from the tabernacles of the Orsanmichele Arts. On that occasion the dark patination intentionally applied at some time after 1789 on almost all the marble statues outside Orsanmichele was removed from the San Marco, probably to assimilate them to bronze statues. It is precisely in such “bronzing” that one of the causes of the numerous brown stains that mark the statue’s surface must be identified.

In order to precisely define the type of compounds present on the surface and to identify the most responsive intervention procedure, a thorough campaign of diagnostic investigations was undertaken, favoring non-invasive methods. Only in one case was a superficial fragment of the old crust that had been retained between some strands of the hair. The sample analyzed was largely composed of the dark patination that covered the work. Analytical pyrolysis coupled with gas chromatography-mass spectrometry, carried out by the Department of Chemistry and Industrial Chemistry at the University of Pisa, confirmed what had already been revealed by examinations conducted by the Opificio in the past, namely that the binder of this ’faux bronze’ treatment was a siccative oil, most likely linseed oil.

The numerous investigations that the Opificio’s scientific laboratory carried out in constant support of the restorers showed that a film was preserved on the surface of the marble composed of the protective applied at the end of the previous restoration and, in part, of the compound used as a detaching agent during the liming operations that followed the intervention by a few years. Of this second material, which had incorporated the deposed atmospheric particulate, the brushstroke marks impressed at the time of its application were clearly visible.

The need to know in depth the state of preservation of the work also led to the realization of U.V. fluorescence shots that clarified the position and design of part of the gilding with which the statue was decorated: the Evangelist’s hair, beard and the borders of his robe were in fact originally richly garnished with gold leaf applied with an oily mission. Scans were also carried out on the work by Studio Micheloni using laser scanning techniques and through photogrammetric techniques aimed at producing high-precision three-dimensional models.

For the cleaning of the work, two lines of intervention were chosen that diversified the work in the back and front parts. On the back, that is, on the parts only rough-hewn, it was possible to use a laser device with 532 nm wavelength emission(Thunder Art). On the front, a first pass with solvent mixtures (applied in the form of gel and emulsion) was necessary to thin the thick layer of substances on the surface, which was followed by a refinishing with laser methodology, in order to rid the sculpture, in a punctual and selective way, of the residues of the old “faux bronze” patina still present on the stone surface. For this phase, the LQS laser (EOS 1000) was used, which proved useful in preserving the traces of gilding still present on the work.

The verification of the surface made it possible to observe that in the left hand of the saint, the same one holding the evangelarium, there are two cylindrical grooves parallel to each other; the grooves, which were completely occluded by dust and soil, indicate that the figure held an attribute, probably a pen.

Donatello’s statue of St. Mark for the Tabernacle of the Arte dei Rigattieri e Linaioli in Orsanmichele is one of the artist’s early masterpieces and a highly innovative work in the history of early Renaissance sculpture. Its execution (c. 1411 - 1413), documented in the pages of the Account Book of the Art, is placed chronologically between two other celebrated Donatello undertakings for the external aediculae of Orsanmichele, St. Peter’s for the Art of the Beccai (1410-1412) and St. George’s for the Art of the Armorers and Spadai (1416-1417). Commissioned from Donatello on April 3, 1411, the date on which the guild assigned the sculptor a block of Carrara marble to give figure to its patron saint, the statue was nearly finished in April 1413. Only the ornaments and gilding were missing, which today can be reread with greater definition, thanks to the recent restoration supported by in-depth diagnostic investigations on the evangelarium cover, among the disheveled locks of the hair and beard, along the borders of the tunic, on the cuffs of the sleeves and on the bangs of the drapes that encircle the waist and shoulders.

Image: Donatello, San Marco (Florence, Orsanmichele Museum). Ph.Credit Mauro and Marco Furio Magliani

Orsanmichele's San Marco, an early work by Donatello, restored

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