{"id":3319,"date":"2021-02-26T15:03:15","date_gmt":"2021-02-26T15:03:15","guid":{"rendered":"https:\/\/libapps.libraries.uc.edu\/thepreservationlab\/?p=3319"},"modified":"2021-02-26T15:03:15","modified_gmt":"2021-02-26T15:03:15","slug":"bite-sized-takeaways-from-photographic-chemistry-study","status":"publish","type":"post","link":"https:\/\/libapps.libraries.uc.edu\/thepreservationlab\/2021\/02\/bite-sized-takeaways-from-photographic-chemistry-study","title":{"rendered":"Bite-Sized Takeaways From Photographic Chemistry Study"},"content":{"rendered":"\n

Introduction and a Little Something About Halides<\/strong><\/p>\n\n\n\n

About two years ago, I set upon a mission to gain expertise in the area of identification and treatment of photographic materials. Under the guidance of our conservator, Ashleigh, I developed an education plan that was split between the theory of learning the ins and outs of photograph identification, and the hands-on work of treating pieces that came into the Lab. Of course, these two things go hand in hand. If you can\u2019t identify a piece, you can\u2019t treat it correctly, right?<\/p>\n\n\n\n

Fast forward to last year. With the start of the pandemic and the transition to working from home, my education plan changed radically. If I\u2019m not in the Lab, I can\u2019t spend much time on treatment, so I had to get a little creative and work on other ways to learn more.<\/p>\n\n\n\n

Enter the American Institute for Conservation\u2019s self-study series on Photographic Chemistry for Preservation<\/a>. It involves eight fairly in-depth units on silver-based analog photographs, how they are created, and as a consequence, how they age and deteriorate.  <\/p>\n\n\n\n

I am about halfway through the series; a triumph for me, as I have never been one for the study of chemistry. I will say that while it is still very technical, I\u2019ve had a lot of good pegs to hang the information on, owing both to my earlier studies in photograph conservation and my personal history with film photography. It\u2019s been a tremendous thing, viewing things that I learned as a photography student from a different angle. So far, it\u2019s been a great journey. <\/p>\n\n\n\n

In this series, I will share with you some of the most fascinating things that I\u2019ve learned so far. My aim will be to keep the technical as simple as possible, for those of you who are like me, still coming to terms with the deeper science. The small bites help it all make sense, I promise. Hopefully, you\u2019ll find it all as interesting as I have.  <\/p>\n\n\n\n

Before we can understand anything else, we need to talk about halides. What are those and why are they used in photography? Good questions! Halide salts are derived from halogens, which occupy group 7A (column 17) of the Periodic Table of Elements (see below.) Halide salts are used in photographic emulsions that are spread over a substrate (such as paper or film) before the substrate is exposed to light. The silver halides react to the light to form an image when developed.  <\/p>\n\n\n\n

I should note here that silver gelatin prints, albumen, and collodion photographs all utilize silver halides in their chemical composition. However, silver gelatin is unique among the three in that it is the only one that uses a true emulsion; in albumen and collodion coatings, the halides rest on the surface.  <\/p>\n\n\n\n