The tintype (also known as a ferrotype) was a type of photographic process invented in the 1850s that involved using a thin sheet of iron (not tin as the name suggests) as the backing for the image (as opposed to film, paper, or glass).
Tintypes became popular in the 1860s and 1870s, but were used into the 21st century despite growing competition from prints on paper, and are currently enjoying a revival in interest. Tintypes could be taken outdoors provided the equipment needed to prepare and develop them was at hand. The process was often used at carnivals and fairs for taking inexpensive novelty photographs in a short amount of time, and a photographer could prepare, expose, develop and varnish a tintype plate in a few minutes. The resulting photograph was sturdy and did not require mounting.
Tintype photographs succeeded the ambrotype, which had some similarities. Ambrotypes also used the wet collodion process, but on a piece of glass that was dark in colour or painted with a black backing. The iron used in tintypes was also coloured black, and the resulting image was actually a negative that appeared positive.