Answer: Gelatin

Gelatin-based desserts have been around for centuries; first as regional concoctions made from gelatin extracted from cattle’s hooves, and then on a commercial scale starting in the early 20th century. By the 1960s, gelatin and the popular Jello-O brand were part of the American landscape. While the majority of us think of gelatin in terms of delicious summer desserts, it also plays a critical role—sans food coloring and flavoring—in the creation of black and white film.

Prior to the 1880s, photographers used a wet-plate process with colloidal silver nitrate. It was a fussy process and the photographic plates had to be created, exposed, and developed in rapid succession. It was impossible to coat a plate for future use.

In the early 1870s, English photographer and physician Richard Leach Maddox became concerned with the health effects of constantly handling the chemicals used in the wet-plate process; specifically, he worried about the fumes from the process and the close proximity of them to the user of the camera.

Maddox began a series of experiments focused on creating dry plates in order to remove the fumes and make photography more enjoyable. His early experiments produced the first useful dry plate technology (prior attempts by other inventors earlier in the century had yielded plates that were too light-insensitive to be useful). The difference in his design? He used a gelatin solution to paint the plates and suspend the silver nitrate upon them. The process was further refined by Charles Harper Bennett and by the 1880s, commercial dry plates crafted using the gelatin method were available.

Although the process has been refined and the carrier material miniaturized and made flexible over the intervening years, modern black and white film is a direct descendant of Maddox’s gelatin-coated plates.