Reilly, using his many years of experience at the Image Permanence Institute, explains the technical aspects of the nineteenth century paper printing process (from the early Calotype and Salted Paper Print to the Albumen Print and later Bromide and "gaslight" papers) and discusses how to best maintain and preserve them. Written with photo archivists in mind, this standard work is excellent information for amature collectors as well.

Starting with the earliest type of paper photograph, the salted paper print, the author illustrates the two basic processes underlying photographic print making: the developing out and the printing out processes.

He recounts the rise of albumen paper as it displaced the salt print taking stock of it's unique qualities and novel albumen look.

The structure of nineteenth-century photographic prints is revealed and applied as a tool for identification of print type and preservation. A great diversity of photographic printing papers existed in the nineteenth-century and identification is key to conservation efforts.