At Paris Photo, I met a woman who is doing research into the "materiality of photography," or in other words, the physical properties of photographs. She's been working with photo-preservationists, restorers and chemists to learn more about photographic paper, which is not—as is all too easy to forget in this age of screen-based image consumption—a simple flat surface. Instead, it's made up of different layers, and they react in different ways to different conditions of light and temperature. Alison Rossiter, an American photographer living in New Jersey, is doing detective work that would fit in here. I also found her work at Paris Photo, where she was represented by two galleries. To make these images, Rossiter (who, not coincidentally, has experience in photographic conservation) located sheets of undeveloped photographic paper from the early 20th century, then developed them herself. The result is a strange, almost haunted series in which we see the fingerprints and dust left behind over the course of decades.