Glass Negatives: the Collodion Wet Plate
Period of Use: 1851 - 1880's

The glass negative was sharp and the prints made from it produced fine detail. Further, the photographer could produce several prints from one negative.

The collodion wet plate can be identified by the unevenly coated emulsion, thick glass, rough edges, and sometimes the photographer's thumb print on the edge.

Commercially available by 1873, gelatine dry plates were usable when dry and needed less exposure to light than the wet plates.  Other distinguishing features were the thinner glass and the evenly coated emulsion.