After the inventions of the daguerreotype and calotype processes in the mid-1800s, the technology behind photography really started to advance. In 1839, English scientist John Herschel informed Talbot and Daguerre of a process to fix images by using silver halides rather than the mercury fumes they had been using. Probably a little safer. He also, in 1841, created a process he called cyanotype. Today we call cyanotypes “blue prints”. The process developed almost 175 years ago is still used today to create blue prints, albeit much less frequently.
Herschel, in 1839, also created the first glass negative. By applying the silver salt solution to a glass plate, he was able to create a very stable, more durable negative. This ushered in a new era of photography. No longer were people trying to get negative or positive images on paper, they were getting them on plates from which a number of paper prints could be made. In 1851, Fredrick Scott Archer created the wet plate collodion process. This process was used to create glass plate positives, tintypes, and even negatives using egg whites or saltpaper. From 1852 to the late 1800s this was the technology of choice as the exposure time was lower, and the technology fairly simple. It was a mess, however, as chemicals needed to be mixed in just the right proportions inside a darkroom or dark tent. It was supplanted by dry plate processes developed in the late 1800s, which were even simpler to use.
Introduced in 1871 by Dr. Richard L. Maddox, it had such rapid success the first factory cranking out dry plates was in place by 1879. Unlike wet plates, which had to be prepared and exposed within minutes, the dry plate used a gelatin emulsion that had been dried. It was found that by drying and heating it, the emulsion actually became more light sensitive allowing reduced exposure times over those of wet plates.
That factory that opened in 1879 was the Eastman Dry Plate Company.
[Image Credit: Public Domain]