By sensitising a pewter plate with wet collodion, previously lacquered in black or brown, one obtained a direct negative, called a ferrotype; this discovery was made by the French photographer Adolphe Martin in 1853. The ferrotype was called a «tintype» in England, where it was known from 1856, the same year as in the United States, where it was christened “melanotype”.
The ambrotype, a process patented in 1854 by James Ambrose Cutting in the United States was a negative image on a glass plate; this was placed in front of a screen with a black rear side (made of paint or cloth), and the picture appeared as a positive.
Both systems were mostly used for portraits, in small format – down to the size of a button or postage stamp – and were then framed or presented in richly decorated cases, or even in jewels. It was often the roving photographer who used these fairly inexpensive processes much in fashion in the 1860s.