Photographs are delicate and require careful consideration of various factors to ensure their longevity, including the materials used in their storage. One standard method for evaluating the safety of storage materials is the Photographic Activity Test (P.A.T.). We'll review the purpose of the test, how the test works, what the results mean, and what you can take away from a product that indicates it passed the P.A.T.
The Photographic Activity Test is an internationally recognized standard (ISO 18916) developed to assess the potential for materials to cause damage to photographs over time. It identifies substances that may contribute to the deterioration of photographs, negatives and slides.
During the P.A.T. testing process, materials are exposed to specific test conditions that simulate the environmental factors encountered during storage. Two detectors are used to determine the possibility of chemical interactions between photographs and their storage materials.
The first tests for chemical reactions that can cause fading, silver mirroring, and red or gold spots (foxing). The second checks for chromophores which can cause yellowing of the material the photograph is printed on.
Materials that pass the P.A.T. pose a minimal risk of causing harm to photographic materials. Institutions and individuals can confidently choose these materials for long-term storage.
Photo safe is not a standardized term and its meaning can vary based on interpretation. "Photo safe" often implies that the materials used are considered to be non-reactive or safe for long-term storage of photographs. However, the P.A.T. is a standardized test method meaning it is a more rigorous and scientific approach to determining the safety of storage and display materials for photographs.