“Tintype: A photographic process in which a direct positive image is produced by a small, lightweight iron plate by a variation of the Collodion Wet Plate process. Popular until the late 19th century, especially with itinerant portrait photographers, who made and sold them cheaply. Also called ferrotype.”
Excerpted from: Diamond, David G. The Bulfinch Pocket Dictionary of Art Terms. Boston: Little Brown, 1992.