Crawford, William. The Keepers of Light: A History & Working Guide to the Early Photographic Processes.

Morgan & Morgan, 1979. Scarce hardcover edition, near fine, illustrated paper over boards, not issued with dust jacket. Custom made polyester jacket. After an excellent introductory history section of more than 100 pages, illustrated with color plates by Julia Margaret Cameron, Joseph Keiley, Edward Steichen, Hill & Adamson, Charles Negre, Henri Le Secq, William Henry Fox Talbot, J.J.E. Mayall, William Notman, Alfred Stieglitz, et al., Crawford provides detailed instructions and discussion of 19th and early 20th century photographic processes, including Salted Paper, Ambrotype, Platinum, Palladium, Kallitype, Carbon, Carbro, Three-Color Carbro, Gum Dichromate, Oil, Bromoil, Photogravure, and Collotype, as well as Color Separation and Conservation and Restoration. Also includes chapter, Early History of Photomechanical Printing, with discussion of Heliography, etched Daguerreotypes, Photogalvanography, Gravure Heliographique, and Woodburytype. Essential reference on this topic.