عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Purpose: Photographs are important records in the process of visual representation of the past culture and civilization in contemporary history. Some changes happen in the structure of historical photographs over time, which may lead to many visual distortions and consequently some conceptual and aesthetic alterations in them. The purpose of this research is to study the chemical degradation that has occurred in two paper-based photographs related to late Qajar and early Pahlavi era. The study includes a description of the two photographs, an assessment of their condition and identification of degradation factors based on the experiments carried out.
Methodology/ Approach: The present study has applied the methods of SEM/ EDS and FTIR to assess the chemical degradation which has occurred in the two photographs.
Conclusion: The results of this study indicate that excess fixing agent has remained on the photographs because of insufficient washing of the fixer during the developing process. The residual fixer has penetrated the emulsion layers and has caused sulfating stains over time because of exposure to humidity. The decomposition of the fixer remaining on the photographs has resulted in some brownish yellow areas and the accumulation of silver on the surface. This has caused fading. This problem is more prominent in the photograph related to the early Pahlavi era. The use of titanium dioxide as the white pigment in the base of the photo paper of this photograph has encouraged the separation of layers. Insufficient washing after applying fixer on the photograph, an improper technique of printing and poor storage conditions comprise the main factors causing the degradation in the studied photographs.