Abstract
Il progetto MEDUSA risponde alla sfida attuale per la comunità internazionale della conservazione di svolgere un ruolo attivo nella società e nella salvaguardia del Patrimonio Culturale, in stretta collaborazione con le istituzioni locali e gli attori nazionali. La diffusa e delocalizzata presenza di opere d'arte esposte all'aperto costituisce un museo a cielo aperto, che rappresenta unicum mondiale e che deve essere valorizzato e preservato per le future generazioni. La proposta progettuale nasce dalla necessità di superare i limiti attuali della ricerca scientifica nel trasferimento tecnologico di prodotti e trattamenti per la protezione dei bronzi esposti in un ambiente marino/costiero e per incoraggiare attività di conservazione preventive. In particolare, il progetto mira a: 1. Condurre un'indagine storica e 'in situ' finalizzata a valutare le proprietà superficiali del bronzo e le prestazioni dei trattamenti di restauro passati. 2. Produrre campioni standard in bronzo con diverse finiture superficiali e patine di invecchiamento naturali, al fine di studiare come il complesso sistema costituito dalla lega di bronzo/patine naturali interagisce con diversi ambienti marini e investigarne le modifiche chimiche, fisiche e morfologiche. 3. Testare un nuovo prodotto sostenibile, come un rivestimento nanostrutturato intelligente progettato con opportuni nanocarriers in grado di rilasciare gradualmente agenti attivi (anticorrosivi, assorbitori UV, antiossidanti) sulle superfici in bronzo. 4. Sviluppare un protocollo analitico sostenibile per monitorare le prestazioni dei trattamenti e fornire agli enti decisionali strumenti per strategie di conservazione preventive sostenibili.
Results achieved
The MEDUSA (MarinE outDoor bronze sUrfaceS: a Methodological Approach) project was conceived to improve the conservation of outdoor bronze artworks exposed to marine environments. Its main challenge was to understand the interaction between bronze alloys, corrosion layers, protective coatings, and environmental factors. Instead of studying these components separately, MEDUSA adopted a holistic approach, considering the bronze surface as an integrated system affected by climate and atmospheric pollutants. The project developed standardized methodologies, analytical protocols, and sustainable conservation treatments to improve the long-term protection of bronze monuments while providing reliable monitoring strategies for conservation practice. A total of 106 bronze mock-ups representative of outdoor monuments were produced by artistic foundry casting. Bare bronze together with green ("Verde Messina") and black ("Liver of Sulphur") artificial patinas reproduced realistic conservation conditions. Standardized measurement grids and dedicated sample holders ensured repeatable analyses throughout the project. A comprehensive non-destructive analytical protocol combined visual, physical, chemical, and electrochemical techniques, including photography, digital microscopy, spectro-colorimetry, eddy-current thickness measurements, surface roughness, FTIR, Raman spectroscopy, hyperspectral imaging, and Electrochemical Impedance Spectroscopy (EIS). Because these techniques generated extensive datasets, multivariate statistical analysis was integrated into the protocol to simplify data interpretation and identify the parameters controlling bronze degradation and coating performance. A major objective was the development of environmentally sustainable conservation treatments. Since conventional corrosion inhibitors such as benzotriazole (BTA) present environmental concerns, MEDUSA designed smart nanostructured coatings based on β-cyclodextrin nanocontainers for the controlled release of corrosion inhibitors. Alongside BTA, the eco-friendly inhibitor AEDTA was investigated by incorporating modified cyclodextrin inclusion complexes into a commercial microcrystalline wax. These multifunctional coatings combined barrier protection with active corrosion inhibition while reducing the environmental impact of conservation treatments. Following laboratory characterization, treated and untreated mock-ups were exposed in two natural marine environments: the industrial atmosphere of Genoa Harbour and the rural coastal site of Capo Granitola (Sicily). Environmental parameters, including temperature, humidity, rainfall, chloride deposition, and time of wetness, were continuously monitored. Samples were periodically analysed after 3, 6, and 9 months using the MEDUSA analytical protocol. Results demonstrated that environmental conditions strongly affected coating durability and corrosion processes. Chloride-rich conditions accelerated coating degradation, confirming the limited long-term performance of traditional wax-based systems. Green patinas generally exhibited better protection than black patinas, particularly at the Genoa site. Electrochemical measurements showed that all coatings significantly improved corrosion resistance immediately after application, although their effectiveness progressively decreased during natural weathering. One of the project's main scientific achievements was the application of multivariate analysis to EIS datasets. This innovative approach enabled efficient interpretation of large electrochemical datasets without relying on conventional equivalent-circuit modelling, providing meaningful parameters for evaluating conservation treatments. The integration of spectroscopic techniques with chemometric analysis also demonstrated strong potential for future in situ diagnostics of outdoor bronze monuments. MEDUSA was carried out through the collaboration between the National Research Council of Italy (CNR) and the University of Bologna, with complementary expertise covering analytical protocol development, mock-up production, conservation treatments, environmental exposure, monitoring, data analysis, and dissemination. The project fully complied with the principles of the National Recovery and Resilience Plan, including DNSH, Open Access, gender equality, generational inclusion, and equal opportunities. Sustainable materials, low-impact laboratory procedures, and digital data management minimized the environmental footprint, while three early-career researchers received training and actively contributed to the project. Dissemination activities included a dedicated website, peer-reviewed publications, conference presentations, Zenodo repositories, and international workshops, ensuring effective knowledge transfer to researchers, conservators, museums, and other stakeholders. Overall, MEDUSA established an innovative methodological framework for investigating and protecting outdoor bronze cultural heritage. By integrating advanced analytical techniques, sustainable conservation materials, environmental monitoring, and multivariate data analysis, the project provides practical tools and scientific guidelines to support future conservation strategies for bronze monuments exposed to changing marine and climatic conditions.Project details
Unibo Team Leader: Daniele Fabbri
Unibo involved Department/s:
Dipartimento di Chimica "Giacomo Ciamician"
Coordinator:
CNR - Consiglio Nazionale delle Ricerche(Italy)
Total Unibo Contribution: Euro (EUR) 63.960,00
Project Duration in months: 24
Start Date:
28/09/2023
End Date:
28/02/2026
