Investigation of cellulose nitrate film-based photographic materials (1902–1917) using a portable Raman spectrometer and chemometric methods

The study is devoted to the development of a safe and reliable methodology for investigation of photographic stereo negative films by methods of molecular spectroscopy using portable devices. The investigation of 200 photographic stereo negative films of the early XXth century that belonged to the Karl Kosse family photographic archive was performed. This archive was donated to the collection of the State Russian Museum and Exhibition Centre ROSPHOTO (St. Petersburg, Russia) in 2013. Due to the presence of artifacts with a different state of preservation, the study of the artifacts contributes to the understanding of the degradation processes and methods of the state control, approaches of restorations and conservations, as well as the historical development of the photographic industry and amateur photography of the late XIX - early XXth centuries.

The portable Raman spectroscopy was selected as the informative technique, giving highly reproducible results. The film base was attributed to cellulose nitrate with the camphor addition for all studied artifacts. It was demonstrated that the safe and reliable results can be obtained with the help of portable Raman spectrometer BRAVO Bruker. Combination of principle component analysis with conjunction of hierarchical cluster analysis made it possible to divide the studied photographic materials into groups on the basis of relative contribution of inorganic compounds detected by Raman spectroscopy.