The Nitrate Cellulose Negatives: Degradation Study via Chemometric Methods

Photographic artifacts carry important historical and cultural information. Materials used in photography at the turn of the XIXth and XXth centuries tend to degrade both over time and if the temperature and humidity conditions of storage are violated. In this connection, the question arises of determining the safety degree and monitoring the condition of photographic materials. Close attention should be paid to photographic materials that become flammable as a result of decomposition. This class of objects includes photographic films based on cellulose nitrate. This study was aimed at examining 100 negatives and stereonegatives from the collection of Karl Kosse dating from 1902 to 1917 as typical examples of these hazard class objects. The degradation of individual negatives was accompanied by a significant change in color—yellowing. The base of photographic negatives (cellulose nitrate and camphor) was determined by Raman spectroscopy, and the presence of a gelatin layer was determined by ATR-FTIR spectroscopy. Using chemometric analysis methods based on the RGB components of digital photos of negatives, an approach has been proposed for determining the state of degradation. The use of the support vector machine approach allows for obtaining a decision boundary, which can be later used to analyze a large data array.