Rome, Jun 9 (EFE).- After eight years of work, the restoration of the New Sacristy of the Medici Chapels, designed and conceived by Michelangelo and located in the Basilica of San Lorenzo in Florence, is complete, thanks to a team of women using an innovative bio-cleaning technique with colonies of bacteria to remove accumulated dirt, shedding a new light on one of Michelangelo’s masterpieces.
The New Sacristy was built by Michelangelo from 1520 to 1534 by papal order to house the remains of Pope Leo X’s brother, Giuliano, Duke of Nemours, and his nephew, Lorenzo, Duke of Urbino.
The Sacristy contains two of the most powerful and dramatic groups of sculptures by the Renaissance master that represent Day and Night and Dawn and Twilight.
The restoration, according to the Bargello Museums group which manages these spaces, “has made it possible to recover the chromatic values of the walls of the New Sacristy, the sculptures and to deepen the technical knowledge that allows us today to better understand the construction phases and the method applied by Michelangelo in the realization of the work”.
The “long and complex” work used “an innovative bio-cleaning technique developed by the ENEA group, used for the first time on Buonarroti’s masterpieces (…) and which uses bacterial colonies to clean the marble from the signs of aging”.
In collaboration with the National Research Council (ISPC-CNR), significant areas were identified on each sculpture for colorimetric and reflectance measurements of the marble.
For instance, the sarcophagus of Lorenzo Duke of Urbino had been altered by dark stains along the entire base that were identified as oxalates and organic materials traced to organic liquids that leaked to the outside of the sarcophagus, dating back to the burial of Alexander de Medici (son of Lorenzo Duke of Urbino), who after being murdered was buried without being eviscerated, as was customary at the time of the Medici dynasty.
To remove these organic stains and others of various origins, such as phosphates, gypsum, traces of silicates, calcium oxalate, bacterial strains were identified that are able to selectively remove these deposits, without damaging the marble.
After testing eleven different bacterial strains on small test pieces, the three “best” ones were chosen to proceed with the biological cleaning of the sarcophagus, the researchers explained.
Packets of cells from the “best” strains infused in a special gel that maintains the right humidity for the bacteria and provides the right consistency for easy application and removal, without leaving residue, were applied to the different parts of the sarcophagus.