The ambrotype (from Ancient Greek: ἀμβροτός — “immortal”, and τύπος — “impression”) also known as a collodion positive is a positive photography on glass made by a variant of the wet plate collodion process. Like a print on paper, the ambrotype is viewed by reflected light. Like the daguerreotype, which it replaced, and like the prints produced by a Polaroid camera, each photography is a unique original that could only be duplicated by using a camera to copy it.
The ambrotype was introduced in the 1850s.
Collodion process, mostly synonymous with the “collodion wet plate process”, requires the photographic material to be coated, sensitized, exposed and developed within about fifteen minutes, while still wet, necessitating a portable darkroom for use in the field.