Uffizi, for the first time a 16th-century canvas restored with essential oils

For the first time in the world, a 16th-century canvas is being restored with the help of essential oils of plant origin. That is, with totally green materials, one might say. The work in question is the Silenzio by Jacopo Zucchi (Florence, c. 1542 - Rome, c. 1596), preserved at the Uffizi in the Terrazzo della Carte Geografiche, and the intervention is the result of a collaboration between the museum in Florence and Policlinico Gemelli in Rome. The undertaking was conducted in the laboratories of theOpificio delle Pietre Dure in Florence, which collaborated with technicians from the Microbiology Laboratory of the Policlinico A. Gemelli IRCCS: it was the microbiologists at the Università Cattolica - Fondazione Policlinico Agostino Gemelli IRCCS who were responsible for developing the mix of bitter orange hydrolate and essential oil of cinnamon bark that enabled the restoration of the painting, which is part of a cycle of nine paintings that adorns the wooden ceiling of the Terrace, recently reopened to the public. Of the nine canvases, which came from Palazzo Firenze in Rome and were transported to Florence at the behest of Ferdinand I in 1588, only ’The Silence’ was subjected to this special green technique during one phase of its restoration. And the results of this study have been published in ’Journal of Fungi,’ a prestigious international scientific journal

The idea stems from an observation: many of the chemicals used in restorations are potentially dangerous to both works of art and human health. For this reason, studies have been underway for some years to identify alternative restoration techniques that are effective but at the same time less aggressive. Valuable from this point of view are the researches focused on certain essential oils and hydrolates, products of natural origin known for their strong anti-bacterial and anti-fungal action.

"The Silence," explains microbiologist Maura Di Vito, a researcher in Microbiology and Clinical Microbiology at the Catholic University, Rome campus, “showed colonization by fungal biodeteriogens on the back of the cloth. Together with Dr. Debora Minotti, a restorer, Dr. Daphne De Luca, a restorer and adjunct professor at the University of Urbino, and Professor Francesca Bugli, my colleague, we have been researching the use of essential oils and hydrolates in restoration for years. Having already completed all the in vitro experimentation and verified the efficacy of these substances on some ancient painted canvases, we have asked for the appropriate authorizations from the Uffizi Directorate to use this ’treatment’ on the ’Silenzio,’ a 1572 canvas painted by Jacopo Zucchi, a pupil of Giorgio Vasari. The ’green’ restoration proposal was positively received, so we started with tandem work between Rome and Florence.”

In order to typify the pathogens diagnostically, the Gemelli microbiologists asked the technical direction of the restoration (entrusted to the Opificio delle Pietre Dure) to noninvasively take samples from both the back and the front of the canvas. Thus, the samples were collected by Dr. Debora Minotti (who graduated from the Florentine institute of restoration and frequently collaborates with it), passing swabs over the colonized part and using, only on the back, fungi-tape, a special ’tape’ that is gently dabbed on the artwork to collect contaminating microorganisms. These samples were then sent to Rome, to the Microbiology Laboratory of the Agostino Gemelli IRCCS University Polyclinic Foundation directed by Professor Maurizio Sanguinetti, Professor of Microbiology at the Catholic University, Rome campus, where they were cultured and typed. “This allowed us,” Professor Sanguinetti explains, “to isolate the two fungal strains that colonized the work and to test them in vitro with our essential oils and hydrolates to verify their efficacy. The contaminating fungi were found to be sensitive to our formulation mix characterized by bitter orange (Citrus aurantium var. amara) hydrolate and a very small amount of cinnamon bark (Cinnamomun zeylanicum) essential oil.”

At this point, everything was ready for surgery. A special “chamber” was set up to treat the important patient, inside which to house the painting during the treatment. After spraying the mix on the back of the canvas and placing on it a sheet of blotting paper soaked in the same mix, the painting was housed inside the “chamber,” a kind of large envelope of Melinex (a monosiliconate polyester film used in some phases of restoration). The canvas thus prepared was laid on a heating and vacuum table for the first few hours; then it was left overnight in the closed environment of the “chamber” with the table turned off. The heating served to bring the fungi into the replication phase, which is their Achilles heel, and allow the treatment to act best by neutralizing the biodeteriogens. The next day everything was removed and the cloth was allowed to dry.

Dr. Di Vito was in continuous visual and audio contact (via Whatsapp) for 24 hours with Dr. Minotti, communicating the delicate points of the new microbiological treatment and identifying with them the best application method. At the end of the restoration, swabs were then repeated to send them to Rome, repeat the cultures and check if the fungi were still present. No fungal growth was visualized from the cultures. “This concluded an interesting team effort,” Professor Sanguinetti adds. “The ’green mission’ was successful and Silenzio was thus returned to the ceiling of the Hall of Maps. This was a pioneering approach in the field of restoration of ancient works using essential oils and hydrolates. This study may pave the way for future new applications on the many world heritage works of art that are simultaneously effective on the work and safe for the operator.”

“The Uffizi Galleries,” concludes museum director Eike Schmidt, “are proud to be working on the most cutting-edge fronts of scientific research.”

Image: Jacopo Zucchi, Il Silenzio (1572; oil on canvas, 135 x 151 cm; Florence, Uffizi Galleries, Terrazzo delle Carte Geografiche). Before and after restoration

Uffizi, for the first time a 16th-century canvas restored with essential oils

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