Tintype

The tintype, also called a ferrotype, is a direct-positive photographic process in which an image is captured on a thin sheet of iron coated with a dark lacquer or enamel and a light-sensitive collodion emulsion. Unlike a process that produces a negative for later printing, the tintype's deliberately underexposed image on the darkened metal reads directly as a positive when viewed, producing a durable, one-of-a-kind photograph with no separate printing step. The process was first described by Adolphe-Alexandre Martin in France in 1853 and patented in the United States by Hamilton Smith in 1856, as a cheaper and faster alternative to the ambrotype and daguerreotype. Its low cost and durability made the tintype especially popular for on-the-spot studio and street portrait photography through the second half of the nineteenth century, and it saw particularly wide use documenting soldiers and battle scenes during the American Civil War, when a finished plate could be developed, fixed and handed to a customer within a few minutes.