AIC's 47th Annual Meeting

Glass manufacturing advanced hand-in-hand with photographic innovations in the 19th century, which commonly incorporated the use of glass as substrates and/or cover glass in encasements. This paper will focus on results to date from an NEH-funded, collaborative research undertaken by the Library of Congress, George Washington University and the Vitreous State Laboratory of the Catholic University of America that includes: (1) investigation into coincidences of practices and developments in the glass industry and the photographic arts, (2) non-invasive analysis of historical glass found in 19th century photographic materials in several historical photographic collections, and (3) study of artificially aged model glass based on typical formulations found in 19th century photographic glass. Preliminary results illustrate how changes in manufacturing methods, distribution and formulation contributed to the diversity of glass types utilized by 19th century photographers in America and other countries. Examination of historical 19th century photographic materials, primarily by microscopy and X-ray fluorescence (XRF), provides new evidence about unstable glass formulations lurking in historical collections, and expands our understanding of the amount and types of unstable glass that exists in such collections. This has implications for both prioritization and conservation practices applied to photographic collections.