Chemical Mapping for Insight into Early 1900s Historical Photographic Films

This study examines the degradation mechanisms of early 1900s gelatin-based photographic films, integrating advanced analytical techniques to provide a comprehensive understanding of the structural and chemical changes within these materials. Ultraviolet hyperspectral fluorescence-induced visible fluorescence mapping (HUVFM) revealed fluorescence quenching in degraded regions, indicative of protein and collagen degradation in the gelatin matrix. Principal component analysis (PCA) revealed distinct spectral responses in these areas, supporting the hypothesis of gelatin degradation. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) clarified the molecular and elemental composition, confirming the removal of the protective paraffin lacquer in the degraded areas and exposing the underlying gelatin. Depth profiling further demonstrated the spatial distribution of degradation products. In addition, the study examined opaque areas related to silver mirroring, proposing the oxidation-migration-reaggregation model as a plausible explanation for this phenomenon. The results highlight the interaction between chemical processes and structural deterioration in gelatin-based photographic films, offering essential insights into conservation strategies.