The tintype was invented in 1851 by Fredric Scott Archer and was the first photographic process accessible to almost everyone in America. Very few tintypes were made outside of America and only the rich had access to the Daguerreotype (released to the world in 1839).
It's use and how it evolved is an American story, deeply rooted in an opportunity to not only document loved ones, but to tell stories, entertain and captivate the viewer.
Deeply rooted to America and Wisconsin's own Georgia O'keefe was married to the person given credit for making photography an art form, Alfred Stiglitz.
The tintype is a positive that cannot be reproduced. It uses collodion with a hallide and silver nitrate to form silver iodide that is suspended in the collodion on a metal plate. Referred to as a wet plate process, the tintype (originally japanned iron) or ambrotype (on glass) must have been made on site while the plate was still wet.
This technology soon became obsolete some 30 years later (gelatin and then celluloid film), allowing the photographer the freedom to rid himself of the portable dark room to produce the image. The formulas and niceties were quickly forgotten until a few people including my mentor and photo historian Mark Osterman reintroduced the process to the masses in the early 2000's.