SurfLand By Joni Sternbach

Tintype, also melainotype and ferrotype, is a photograph made by creating a direct positive on a sheet iron metal that is blackened by painting, laquering or enamelling and is used as a support for a collodion photographic emulsion.
Photographers usually worked outside at fairs, carnivals etc. and as the support the tintype (there is no actual tin used) is resilient and does not need drying, instant photographs can be produced only a few minutes after taking the photograph.
An ambrotype uses the same process and methods on a sheet glass that is mounted in a case with a black backing so the underexposed negative image appears as a positive. Tintypes did not need mounting in a case and were not as delicate as photographs that used glass for the support.