Tintype (Ferrotype) (1855-1890)

Though already waning in popularity by the 1870's, tintypes were still produced throughout the 1880's and into the 1890's.  
A small tin or copper plate, often clipped somewhat irregularly with blunted corners, was coated with a dark, molasses-like lacquer prepared with an iodine- or bromine-based collodion emulsion.   After exposure, this plate was developed, fixed, and rinsed, then sheathed in a protective paper sleeve with an oval window. The light-coloured negative image produced a positive likeness on the dark background.    Each tintype was a one-of-a-kind image.   This medium's dark, sombre image was fragile and susceptible to cracking and blistering.