Mapping damage and biological agents in Greek historical photographs from 1938 to 1948 using multi-analytical methods

The present study aims to assess the preservation state of ten historical photographs from the years 1938 to 1948. These photographs are significant historical documents from a tumultuous period marked by World War II and the Greek Civil War. The methods utilized to evaluate the preservation state of the photographs include multispectral imaging, macro and micro imaging, biological analysis, optical microscopy, and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM/EDS). Multispectral imaging provided significant information on stratigraphy of photographs and the damage of photographs. Moreover, it revealed suspected biological growth in certain areas which was verified, leading to further study of these biological factors and thus the fungal genus Aspergillus spp. was identified. At the same time, SEM/EDS analysis was conducted to investigate the materials and manufacturing techniques used, providing simultaneously, insights into both abiotic and biotic elements. This analysis identified materials and techniques such as the Baryta layer, silver chloride emulsions, and additives used in the chemical production baths of photographs. Overall, the application of this comprehensive methodology allowed us to effectively map the preservation state of the photographs, highlighting the critical influence of material quality and production techniques on their condition. The results obtained from non-invasive multi-analytical methods proved to be precise and valuable for this purpose.