We often use the word photograph when referring to the positive image on paper that is a familiar fixture in our daily lives. In reality, a photograph can be one of many processes in which light-sensitive media are employed to create a visible image. The prevalence of photographs allows us to forget that they are potentially fragile objects that can be easily damaged by careless handling, improper storage, and exposure to environmental influences such as light, humidity, and temperature. In caring for a photographic collection, it is important to know that various components create a photograph. The interaction of these components, with each other and with their environment, has a lasting effect on the longevity of the image.
Most photographs consist of a final image material, a binder layer, and a primary support.
The final image material - commonly silver, platinum, organic dyes, or pigments creates the image we see. The binder layer is a transparent substance albumen, collodion, or gelatin in which the final image layer is suspended. The binder and final image material are applied to a primary support, usually paper, glass, metal, or plastic. Although many photographs have this three-part structure, individual images may have additional components. For instance, applied color or coatings and original frames or cases need to be considered as part of the photographic object.