The platinum process descended from other iron based processes such as Cyanotype in the mid 1860's. Known as Platinotype, it was patented by William Willis, of Great Britain, in 1873. The Platinotype gained much popularity being both beautiful and the most archival of any printing process. With the increasing cost of platinum and the mass production of fine gelatin silver papers in the mid 1930's, Platinotype fell by the wayside. Although, several photographers continued to make fine platinum prints.In the early 1970's two things happened. Commercial gelatin silver paper was lessening in quality. And, George Tice wrote an article on hand coated platinum prints in Caring for Photographs, a volume of the Life Library of Photography published by Time Life Books in 1972. This rekindled the interest in hand coated platinum prints. Several contemporary photographers prefer to utilize this process because they find the platinum print to be a most beautiful object. Others, such as the author, find that the Platinotype process more closely represents the way they wish to see the image.
For some fascinating information on the history of the platinotype, read The Eighth Metal: the Rise of the Platinotype Process by Mike Ware located on his web site.