Folio 843 of Codex Atlanticus. Credit: Folio 843 of Codex Atlanticus, Veneranda Biblioteca Ambrosiana, Milan
A thorough study, published in Scientific Reports, was carried out by Politecnico di Milano on folio 843 of the Codex, to comprehend the origins of some black spots that appeared a few years earlier on the modern passepartout that binds Leonardos initial folios.
The research study carried out by the Politecnico began in 2021 throughout an initial pilot job on three Codex illustrations moneyed by Fondo Italiano di Investimento, which included the removal and replacement of the passepartout of the folio 843.
The presence of mercury could be associated with the addition of an anti-vegetative salt in the glue mixture used in Grottaferratas restoration techniques, which might have been applied only in specific areas of the passepartout paper, precisely where it holds Leonardos folio, to guarantee adhesion and prevent microbiological infestations on the Codex.
Black stains on the passepartout of the Folio 843 of Codex Atlanticus. Credit: Politecnico di Milano
The Codex Atlanticus, contributed to the Veneranda Biblioteca Ambrosiana in 1637, was the topic of a major restoration brought out by the Laboratorio del Libro Antico (Laboratory for the Restoration of Ancient Books) of the Abbey of Grottaferrata between 1962 and 1972. The intervention ended with the production of 12 volumes with 1119 folios: each page has a passepartout with a panel (added by the conservators in Grottaferrata) framing Leonardos original pieces. Since 1997, the Codex has actually been stored in an environment with a strictly managed microclimate, in accordance with paper preservation standards.
This phenomenon of blackening, observed on some 210 pages of the Codex from folio 600 onwards, has actually caused fantastic issue amongst museum managers and scholars. The research study brought out by the Politecnico started in 2021 throughout a preliminary pilot job on three Codex drawings moneyed by Fondo Italiano di Investimento, which included the elimination and replacement of the passepartout of the folio 843.
Nano-particles made up of mercury and sulfur on Folio 843 of Codex Atlanticus. Credit: Politecnico di Milano
Previous studies had ruled out that the discolorations arised from microbiological wear and tear procedures. Research by the Politecnico di Milano, integrating hyperspectral photoluminescence imaging and UV fluorescence imaging with micro-ATR-IR imaging, revealed the existence of starch glue and vinyl glue situated in the areas where the staining is most focused, ideal near the edge of the folio.
In addition, the presence of round inorganic nanoparticles, 100-200 nanometres in size, made up of mercury and sulfur, was spotted, which had actually accumulated within the cavities formed between the cellulose fibers of the passepartout paper. Utilizing synchrotron analysis, conducted at ESRF in Grenoble, it was possible to identify these particles as metacinnabar, a mercury sulfide in an unusual black crystalline stage.
Extensive studies on paper preservation techniques have allowed us to create some hypotheses on the formation of metacinnabar. The existence of mercury might be connected with the addition of an anti-vegetative salt in the glue mixture utilized in Grottaferratas repair techniques, which might have been applied just in certain locations of the passepartout paper, precisely where it holds Leonardos folio, to guarantee adhesion and prevent microbiological problems on the Codex. The presence of sulfur, on the other hand, has actually been linked to air contamination (in Milan in the 1970s, levels of sulfur dioxide SO2 were very high) or to the additives utilized in the glue, which gradually would have caused a response with mercury salts and the formation of metacinnabar particles, responsible for the black spots.
Recommendation: “Imaging and micro-invasive analyses of black spots on the passepartout of Codex Atlanticus Folio 843 by Leonardo da Vinci” by Nicolò Guarnieri, Marta Ghirardello, Sara Goidanich, Daniela Comelli, David Dellasega, Marine Cotte, Elena Fontana and Lucia Toniolo, 25 March 2023, Scientific Reports.DOI: 10.1038/ s41598-023-31129-2.
Folio 843 of Codex Atlanticus. Researchers from Politecnico di Milano found that black spots on the Codex Atlanticus passepartout were triggered by metacinnabar, a black crystalline stage of mercury sulfide, due to a mix of restoration techniques, air contamination, and additives in the glue utilized during the repair process. Credit: Folio 843 of Codex Atlanticus, Veneranda Biblioteca Ambrosiana, Milan
A study released in the distinguished journal Scientific Reports has revealed the nature of the black stains on the passepartout of the ancient file.
The Codex Atlanticus is among the most fascinating and comprehensive collections of Leonardo da Vincis illustrations and works. Its preservation is a terrific challenge for researchers and scholars. An extensive study, released in Scientific Reports, was carried out by Politecnico di Milano on folio 843 of the Codex, to comprehend the origins of some black discolorations that appeared a couple of years back on the modern passepartout that binds Leonardos original folios.
The interdisciplinary research study team coordinated by Lucia Toniolo, Professor of Materials Science and Technology at the Politecnico di Milano, used a series of micro-invasive and non-invasive analysis techniques to examine the phenomenon and study its nature and causes.
