Negatives made of glass, rather than paper, brought a new level of clarity and detail to photographic printing, making the collodion—or wet-plate—process popular from the 1850s through the 1880s. It was discovered in 1851 by Frederick Scott Archer (1813–1857).

As the name suggests, the wet plate process must be completed before the chemicals dry. First, the glass plate must be perfectly cleaned. Next, in the dark or in the very feeble light of a dark chamber, collodion, a viscous solution of nitrocellulose dissolved in alcohol and ether, combined with potassium iodide is poured onto the glass plate until evenly coated. The glass is then submerged in a solution of silver nitrate, which reacts with the potassium iodide, making the plate sensitive to light. The sensitized plate is then placed in a camera and exposed. After exposure, the plate is developed in pyrogallic acid. A fixer of sodium thiosulfate, or hypo, is necessary to keep the plate from undergoing further exposure. The plate is then washed, dried, and ready for printing.
In addition to the wet plate process producing negatives for printing on paper, the basic chemistry was the foundation for the tintype and the ambrotype.