
One of my classes this semester is a photography preservation class. Part of doing archival work around photographs involves identifying different photography processes. There are many ways of making a photograph, even from the earliest days of photography in 1839. Some photographs are one of a kind objects, other photography techniques involve creating a photo negative that is then developed into a positive print.
This week we were challenged to identify a photograph either from our own collections or from an archive or other repository. Since most archives are closed right now, I chose one of the prints in my own photography collection.
This photo is a gelatin silver DOP print, which was one of the most popular print techniques of the 20th century. You can’t see it from the photo, but it has a high gloss finish, which became popular during the 1930s.
My Nana was able to tell me a lot more about the people in the photograph and when and where it was taken, so learning about the photograph’s process also meant that I learned more about my family history.
Are you interested in learning about your own family photographs? Graphics Atlas has great information about identifying different kinds of photography and has great information about the science behind each kind of photo process. It shows views under magnification and commons signs of deterioration.

For example, my family photo shows signs of silver mirroring in the darkest areas. See that silvery blue sheen in the photo? That means that the silver has migrated closer to the surface in areas that are really dark (where there was a high density in silver to develop the photo).
Why do archives care about identifying photos?
- It helps to date photos. By identifying the process, we can have rough estimates about the date based on when the technique was being used. That said, this isn’t foolproof because some really old techniques are still being used by photographers today.
- It helps with preservation. Knowing the ideal conditions for a photograph or a negative is dependent on knowing the kind of artifact you’re working with.
- It helps with access. Importantly, knowing that you have a specific type of print can help researchers looking for specific kinds of photos to study.
What’s the oldest family photo you have? Let me know in the comments!