Dating old tintypes
The tintype was essentially a variant of the ambrotype, replacing the latter's glass plate with a thin sheet of japanned iron (hence ferro).
Ambrotypes often exhibit some flaking of their black back coating, cracking or detachment of the image-bearing emulsion layer, or other deterioration, but the image layer on a tintype has proven to be typically very durable.
It began losing artistic and commercial ground to higher quality albumen prints on paper in the mid-1860s, yet survived for well over another 40 years, living mostly as a carnival novelty.
The tintype's immediate predecessor, the ambrotype, was done by the same process of using a sheet of glass as the support.
The process was first described by Adolphe-Alexandre Martin in France in 1853.
In 1856 it was patented by Hamilton Smith in the United States and by William Kloen in the United Kingdom.
It was first called melainotype, then ferrotype by a rival manufacturer of the iron plates used, then finally tintype.
Although early tintypes were sometimes mounted in protective ornamental cases, like daguerreotypes and ambrotypes, uncased tintypes in simple paper mats were popular from the beginning.
They were often later transferred into the precut openings provided in book-like photograph albums.A tintype, also known as a melainotype or ferrotype, is a photograph made by creating a direct positive on a thin sheet of metal coated with a dark lacquer or enamel and used as the support for the photographic emulsion.Tintypes enjoyed their widest use during the 1860s and 1870s, but lesser use of the medium persisted into the early 20th century and it has been revived as a novelty in the 21st.The ambrotype was the first use of the wet-plate collodion process as a positive image.