A film cartridge for 35mm 35mm cameras, cast in bronze and silver-plated in a film fixing bath.
During film development, the silver halides contained in the film are chemically reduced to silver, and the image becomes visible. The darker a spot is on the film, the more silver is present. Lighter areas are still sensitive to light after development. In the fixing bath, the remaining silver halides are dissolved from the film and accumulate in the fixing bath.
Later, I place the bronze film cartridge in the fixing bath. A thin layer of silver accumulates around the cartridge.