Tintype is an old photographic process that imprints images on sheets of iron. David Emitt Adams used this method to print landscape images of the American Southwest on metal cans. He writes:
For this body of work, I collect discarded cans from the desert floor, some over four decades old, which have earned a deep reddish-brown, rusty patina. This patina is the evidence of light and time, the two main components inherent in the very nature of photography. I use these objects to speak of human involvement with this landscape and create images on their surfaces through a labor-intensive 19th century photographic process known as wet-plate collodion.
Link -via Junkculture