The ferrotype, also called the tintype or melainotype, is a photographic process developed in the United States in the 19th century. It superseded the ambrotype by the end of the Civil War and went on to become the most common photographic process until the introduction of modern "film" based processes. Ferrotypes waned in popularity by the end of the 19th century, although a few makers were still around as late as the 1950’s.
The ferrotype was a minor improvement to the ambrotype in that it replaced the glass plate of the original process with a thin piece of black enameled iron (thus "ferro") or tin. The new materials reduced the cost of the productions considerably, and the image, trapped between the metal and varnished surface, has proven to be very durable. Like the ambrotype, the image is technically negative, but because of the black background, appears as a positive. Since the ferrotype 'film' was the same as the final print, most ferrotype images appear reversed (left-to-right) from reality. Some cameras were fitted with mirrors or a 45-degree prism to reverse and correct the image, while some photographers would photograph the reversed ferrotype to produce a properly oriented image.
Ferrotypes were simple and fast to prepare. A photographer could prepare, shoot, develop and varnish a ferrotype plate in a few minutes, having it ready for a customer quickly. The earlier ferrotypes were often cased, like daguerreotypes and ambrotypes, but uncased images in paper sleeves became more common after 1870.