ambrotype
n.
A positive photograph on glass made using the wet-collodion process, often hand-tinted and mounted in a hinged case.
Notes
An ambrotype is an underexposed, underdeveloped, wet-collodion negative on glass that, when viewed with a dark background, appears as a positive image. The dark background is commonly a black varnish applied to the glass base but is sometimes a separate material behind the glass or the glass base itself may be dark. The same process using a black-varnished metal plate is known as a tintype.Ambrotypes were patented in 1854 by James Ambrose Cutting and were common through the 1870s. They largely supplanted daguerreotypes.
