Mapping Bronze Disease Onset by Multispectral Reflectography

Year: 2025

Authors: Porcu D., Innocenti S., Striova J., Carretti E., Fontana R.

Autors Affiliation: CNR, Natl Inst Opt CNR INO, Largo E Fermi 6, I-50125 Florence, FI, Italy; Univ Roma La Sapienza, Dept Sci Antiqu, Piazzale Aldo Moro 5, I-00186 Rome, RM, Italy; Univ Florence, Dept Chem Ugo Schiff, Via Lastruccia 3-13, I-50019 Sesto Fiorentino, Fi, Italy; Univ Florence, CSGI Consortium, Via Lastruccia 3-13, I-50019 Sesto Fiorentino, FI, Italy.

Abstract: The early detection of bronze disease is a significant challenge not only in conservation science but also in various industrial fields that utilize copper alloys (i.e., shipbuilding and construction). Due to the aggressive nature of this corrosion pathway, developing methods for its early detection is pivotal. The presence of copper trihydroxychlorides is the main key indicator of the ongoing autocatalytic process. Commonly used for pigment identification, reflectance imaging spectroscopy (RIS) or fiber optics reflectance spectroscopy (FORS) was recently employed for mapping atacamite distribution in extended bronze corrosion patinas. In this work, we detected the onset of bronze disease using visible-near-infrared (VIS-NIR) multispectral reflectography, which allowed for disclosing features that were poorly detectable to the naked eye. The image cube was analyzed using the spectral correlation mapper (SCM) algorithm to map the distribution of copper trihydroxychlorides. FORS and Raman spectroscopy were employed to characterize the patina composition and validate RIS data. A set of bronze samples, representative of Florentine Renaissance workshops, was specifically realized for the present study and artificially aged at different corrosion stages.

Journal/Review: MINERALS

Volume: 15 (3)      Pages from: 252-1  to: 252-15

More Information: This research was funded by PE_00000020-CHANGES: Cultural Heritage Active Innovation for Sustainable Society project, PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR)-MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.3-CUP D53C22002560006, funded by Next Generation EU. S.I. acknowledges PNRR H2IOSC (Humanities and Cultural Heritage Italian Open Science Cloud) Project (IR0000029), CUP_B63C2200073005, funded by Next Generation EU. The contents reflect only the authors’ view, and the European Commission is not responsible for any use that may be made of the information it contains.
KeyWords: reflectance imaging spectroscopy; atacamite; bronze corrosion; Raman spectroscopy; fiber optics reflectance spectroscopy; principal component analysis; spectral correlation mapping
DOI: 10.3390/min15030252