The chemical pioneers
Photography's first professionals were part chemist, part showman: daguerreotypists coating, sensitizing and developing plates by hand for sitters who had never seen their own faces fixed in metal. Studios spread from Paris and New York to Bombay, Cairo and Yokohama within two decades, and by the 1850s American operators alone were making millions of portraits a year. The wet collodion process then destroyed that first trade in turn — cheaper tintypes and paper prints replaced the jewel-like daguerreotype almost completely within a decade of 1851.