High-lateral resolution image recovery and degradation mapping of daguerreotypes using mobile reflectance, ?-XRF, MA-XRD, and benchtop ?-vibrational spectroscopies
Year: 2026
Authors: Balbas D.Q., Ravan E.L., Botticelli M., Caliri C., Brancolini T., Cagnini A., Romano F.P., Striova J.
Autors Affiliation: Natl Inst Opt CNR INO, Natl Res Council, Largo E Fermi 6, I-50125 Florence, Italy; Ist Sci Patrimonio Culturale CNR ISPC, Consiglio Nazl Ric, Via Biblioteca 4, I-95124 Catania, Italy; Sapienza Univ Rome, Piazzale A Moro 5, IT-00185 Rome, Italy; Opificio Pietre Dure MiC, Sci Lab, Viale F Strozzi 1, I-50129 Florence, Italy.
Abstract: The study of daguerreotypes, one of the earliest photographic process, requires analytical methods that address both their metallic composition and the high spatial resolution of their images. This work presents results obtained with research-grade laboratory instruments for image recovery and chemical characterization of degraded daguerreotype plates. Our methodology combines two transportable instruments with high lateral resolution for the image recovery: reflectance imaging spectroscopy (RIS) in the visible and near-infrared (Vis-NIR) ranges (400-2500 nm, lateral resolution 125 mu m), which was used to study the optical properties of the plate, and micro-X-ray fluorescence (mu -XRF) mapping (lateral resolution <= 40 mu m), which provided chemical information at spatial resolution comparable to synchrotron-based mu -XRF (10-50 mu m) while offering the practical advantage of laboratory and field analysis, free from the limitations of large-scale facilities. Additionally, macro-X-ray diffraction (MA-XRD) and micro-vibrational spectroscopy (mu -Raman and mu -FTIR in reflection mode) mapping were applied to investigate, at a mesoscale, specific regions of interest (ROIs) to deepen the chemical characterization of the copper corrosion products, such as formates and oxides, present on the surface. Spot-wise micro-confocal-XRF (C-XRF) was used to study the stratigraphic distribution of elements in the plate to understand the corrosion mechanism. Our findings demonstrate the capabilities of image recovery with RIS, particularly in the NIR spectral range, and mu -XRF in tracing the Hg-L spatial distribution. This multi-scale methodology, combining macro-, meso-, and spot-wise scales, is particularly useful for documenting the image condition across the entire plate and for mapping the distribution of degradation products in regions of interest (ROIs). Such information is crucial for guiding conservation strategies in daguerreotype collections. Journal/Review: TALANTA (OXF.)
Volume: 299 Pages from: 129140-1 to: 129140-12
More Information: This research has been funded by the Diagnostica Non invaSiva e conservazione di daghErrotipi e altri materiali fotografici (DIAGNOSE) project co-funded by Tuscany Region, P OR FSC 2014-2020-Axis Employment GiovaniSi (Grant No. CUP B53D21008070008), Museo Galileo, El.En. group, and the National Institute of Optics from the National Council of Research (CNR-INO), in collaboration with the Opificio delle Pietre Dure (OPD). This work was supported by the H2IOSC Project-Humanities and Cultural Heritage Italian Open Science Cloud (https://www.h2iosc.cnr. it/), funded by the European Union NextGenerationEU-National Recovery and Resilience Plan (NRRP)-Mission 4 Education and Research Component 2 From research to business Investment 3.1, Fund for the realization of an integrated system of research and innovation infrastructures, Action 3.1.1 Creation of new research infrastructures strengthening of existing ones and their networking for Scientific Excellence under Horizon Europe – Project code IR0000029-CUP-B63C22000730005. Implementing Entity CNR. Further support was received from CHANGES, SPOKE 5 Science and Technologies for Sustainable Diagnostics of Cultural Heritage [PE 0000020, CUP B53C22003890006, NRP M4C2 Investment 1.3, Funded by the European Union-NextGenerationEU]; SAMOTHRACE, Sicilian MicronanoTech Research And Innovation Center [ECS 622 00000022, CUP B63C22000620005, NRP M4C2 Investment 1.5, Funded by the European Union-NextGenerationEU]; and E-RIHS.it Italian national node of the European Infrastructure of Heritage Science (E-RIHS) funded by the European Commission [H2020-INFRADEV-2016-2, GA 739503].KeyWords: mu-XRF imaging; MA-XRD mapping; mu-Raman mapping; mu-FTIR mapping; Vis-NIR imaging; DaguerreotypesDOI: 10.1016/j.talanta.2025.129140
