Innovative application of X-radiography in the study of daguerreotypes: Hallmarks and identification

X-radiography is an imaging technique widely used in the examination of works of art and heritage objects; however, no references to its application in the study of daguerreotypes have been found. The results obtained in this study demonstrate, for the first time, the usefulness of X-radiography for locating, identifying, and characterising hallmarks on daguerreotype plates. Hallmarks are of great importance for comprehending these photographic artefacts, as they can provide valuable information for dating, details on the production process, and potential attribution. In this study, four daguerreotypes were X-rayed employing two different working procedures designed with the aim of recording the hallmarks: one by means of radiographic film, and the other using a digital detector. The presented working procedures enabled the discovery of the hallmark locations on all studied daguerreotypes and their positive identification. This was able to be done without extracting the daguerreian package or handling the plate, thereby avoiding exposure to damaging environmental factors. X-radiography is thus revealed as an innovative and easily integrated tool for the study of daguerreotypes, both for the characterisation of hallmarks on the plate and for analysis of other elements and manufacturing procedures. (c) 2024 Consiglio Nazionale delle Ricerche (CNR). Published by Elsevier Masson SAS. All rights reserved.