Photographic collections, standing as testimony to our history for nearly 180 years, are made up of various kinds of items. They include both photo documentaries and artistic images, and may be held in public and private institutions (museums, archives and industries) or by private collectors. They are made up of very diverse materials (metal, polymer, glass, pigments, metallic salts, etc.) stemming from a multitude of photographic processes and image supports. Photographs are sensitive to their surrounding conditions and thus vulnerable – to a greater or lesser extent – to deterioration of the image or support along various time scales.
The Photographic Materials section of the CRCC is dedicated to developing knowledge on early photographic processes, photographic materials and their stability, and, through its research on long-term preservation and storage of collections, to contributing to the preservation of photographic heritage.
Our research includes (i) identification of the materials of which photographs are made and of the photographic processes used, (ii) investigation of physical-chemical phenomena involved in photographic processes, (iii) evaluation and comprehension of deterioration of photographic materials in order to contribute to developing and adapting preservation best practices.
This is why we work not only on model systems prepared in the lab, but also on vintage photographs. We characterize the physical and chemical properties of photographs’ components and seek to identify the physical-chemical mechanisms of any degradation. The study of photographic materials, which are intrinsically photosensitive, is challenging in terms of physical-chemical analysis. We therefore develop methodologies to study photographic materials from macrometric scale to sub-micrometric scale, using microscopy (photonic, electronic) and spectroscopy (X-rays, vibrational).
Since April 2014, two studies have been in progress:
1. The deterioration of Prussian blue pigment used in early photographic processes: cyanotypes and Louis Ducos du Hauron trichromies. In collaboration with Claire Gervais from the Bern University of the Arts, in Switzerland.
2. The origin of the colors in Edmond Becquerel’s photochromatic images from 1848. These pictures are the first successful attempts at color photography. Nevertheless, Becquerel failed to solve the stability problem for the solar spectrum that he recorded on silvered plates. The first year of this frontier research was funded by Sorbonne University. We were proud to organize the “Edmond Becquerel and the Birth of Color Photography” symposium held 10 December, 2015.
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- Marie-Angélique Languille | Heritage scientist