Setting up a methodology for restoring degraded daguerreotypes using UV lasers and atmospheric non-thermal plasma cleaning techniques
Year: 2025
Authors: Balbas DQ., Dimitroulaki E., Melessanaki K., Cattaneo B., Cagnini A., Bartoli L., Falzacappa EV., Scopece P., Pouli P., Striova J.
Autors Affiliation: CNR, Natl Inst Opt CNR INO, Largo E Fermi 6, I-50125 Florence, Italy; Fdn Res & Technol Hellas IESL FORTH, Inst Elect Struct & Laser, N Plastira 100, GR-70013 Iraklion, Greece; Opificio Pietre Dure MiC, Lab Restauro Cartacei & Membranacei, Viale F Strozzi 1, I-50129 Florence, Italy; Opificio Pietre Dure MiC, Sci Lab, Viale F Strozzi 1, I-50129 Florence, Italy; El En SpA, Via Baldanzese 17, I-50041 Florence, Italy; Nadir Srl, Via Don Federico Tosatto 15, I-30174 Venice, Mestre, Italy.
Abstract: Since the early years of the development of daguerreotypes-the first commercial form of photography made public in 1839-cleaning procedures have been necessary due to their tendency to tarnish. Cleaning daguerreotypes is challenging, and conventional methods often result in undesirable effects or prove impractical, especially for hand-colored plates. In recent decades, advanced techniques, such as laser and plasma cleaning, have been optimized for tarnish removal. However, their effectiveness in removing other substances, such as by-products of previous cleaning treatments, has not been evaluated. To address this issue, we investigated the efficacy of laser and atmospheric non-thermal plasma cleaning on two 19th-century daguerreotypes exhibiting two different degradation conditions: one with typical tarnish, and the other with a complex layer composed of cyanides, calcium carbonate, and an organic compound, likely produced during a previous cleaning attempt. This work reports systematic tests using visible (VIS) and ultraviolet (UV) lasers emitting at four different wavelengths: Nd:YAG (532 nm, 355 nm), KrF excimer (248 nm), and ArF excimer (193 nm). All the lasers operated in the nanosecond regime, except for the KrF excimer laser, which was also tested with femtosecond (500 fs) pulse duration. This is the first report of results using the 248 nm wavelength in both ns and fs regimes for daguerreotype restoration. For comparison, we also applied atmospheric non-thermal plasma cleaning to both types of degradation. The experiments allowed us to assess the advantages and limitations of both techniques, showing that both are suitable depending on the specific surface condition. Additionally, we evaluated a combined cleaning strategy that involved laser and wet cleaning with two different substances-distilled water and an EDTA solution-to optimize the cleaning outcomes. To make an informed selection of the parameters and evaluate treatment efficacy, we characterized the chemical composition and morphology of the daguerreotypes and their degradation products before and after cleaning using optical microscopy, mu -Raman spectroscopy, and SEM-EDS. Besides the identification of the degradation products, the analytical results provided a critical review of previous literature on laser cleaning of daguerreotypes and supported the determination of the best experimental conditions for the safe removal of degradation layers from the surface of daguerreotypes. (c) 2025 The Author(s). Published by Elsevier Masson SAS. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Journal/Review: JOURNAL OF CULTURAL HERITAGE
Volume: 74 Pages from: 289 to: 299
More Information: This research has been funded by the Diagnostica Non invaSiva e conservazione di daghErrotipi e altri materiali fotografici (DIAG-NOSE) project co-funded by Tuscany Region, POR 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).The experimental work was conducted at the Ultraviolet Laser Facility at IESL-FORTH in Greece, supported in part by the European Community’s Horizon 2020 research and innovation program LASERLAB-EUROPE (Grant Agreement No. 871124), through the project Laser cleaning of daguerreotypes (PID 27277).D.Q.B. is 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.KeyWords: Excimer KrF in femtosecond regime; Laser cleaning; Daguerreotypes; Atmospheric non-thermal plasma cleaning; Heritage scienceDOI: 10.1016/j.culher.2025.06.021
