The Degradation of Daguerreotypes and the Relationship with Their Multi-Material Structure: A Multimodal Investigation

Abstract

Preserving and analytically examining daguerreotypes is particularly challenging because of their multi-material and multi-component structure. Various sensors have been exploited to examine mainly the image plates of the daguerreotypes even though the degradation goes beyond this component. Micro-analyses have been the preferred method due to the nanoscale structure of the image particles. In this work, we propose comprehensive multi-modal non-invasive sensing to investigate the corrosion products present in nine daguerreotypes from the Fondazione Alinari per la Fotografia (FAF, Florence, Italy). The methodology proposed includes chemical and morphological analyses: portable X-ray fluorescence spectrometry (pXRF), Raman microspectroscopy (μ-Raman), and micro-Fourier transform infrared spectroscopy in reflection mode (μ-rFTIR) for the chemical identification. For the first time, optical coherence tomography (OCT) was deployed to record the cross-sectional and morphological data of the relevant corrosion formations on daguerreotypes in a contactless way. The results allowed the characterization, in a non-invasive mode at a microscopic level, of a wide range of degradation products produced by the interaction of the different elements present in the structure of the daguerreotypes. The aim was to verify the performance of the proposed methodology and to link the chemical and physical complexity of the entire structure, disclosed by the state-of-art sensors, to the daguerreotype degradation. The results draw attention to the need to monitor not only the image condition but the whole object as a partially closed system in constant interaction internally and with the environment.

All-Photon Bipolar Reversible Modulation Artificial Synapse for Color Perception and Mitigation of Glare Phenomenon

“…The cessation of light exposure prompts the newly generated I 2 to react with Ag, regenerating AgI (eq 2). 57 This gradual process facilitates the return of the device to its low-resistance state prior to light exposure.…”

3D scanning of daguerreotypes

“…For instance, confocal microscopy was applied to monitor the effect of cleaning methods on the micro-topography of the plate surface [7]. Similar attempts have been made with optical coherence tomography to register the effect of laser induced breakdown spectroscopy measurements on the surface and to correlate the data with the stratigraphic distribution of the elements detected [12], or to study corrosion deposits, such as copper formates [13].…”