Popular Photographic Print Processes:
Platt D. Babbitt, photographer. [Niagara Falls].
Ambrotype, ca. 1854.
general use: ca. 1851-1865
Description: A direct-image photograph commonly associated with the daguerreotype, because it was often made in a similar size and kept in a case. The ambrotype is essentially an underexposed or "thin" collodion glass negative with dark material placed behind it. This causes the negative to appear as a positive image. Compared to the daguerreotype, it is a duller, less contrasty image. Unlike the daguerreotype, the image does not have a mirror-like surface. The ambrotype was less expensive to make than a daguerreotype.
Further information and examples
Print Processes Introduction and Table