Plate

Two packs of Kodak plates. These packs are dated (in pencil) to 1953 and 1956. image by Nicholas Middleton (Image rights)

Plates are a photographic medium, which may broadly be described as the predecessor of film. The term plate refers to the fact that the photographic emulsion is supported on a sheet (or plate) of glass.

Since the late 19th century, the term has been more or less synonymous with dry plates. They have to be distinguished from wet plates which are simply glass plates which fit into the plate holder of a wet plate camera. Those glass plates have to be prepared in a dark chamber with a light sensitive emulsion and must be exposed when still wet. The first of these processes was the Wet-collodion process.

Dry Plates

Dry plates are also glass plates or better glass sheets, but coated with a light sensitive emulsion in the factory. The emulsion film on the glass plate is dried before the plates are packaged light-tight for distribution. The Albumen plates were an early variant of these film plates. For most dry plate cameras the plate holders have to be loaded in a dark room. But then the plates in the light-tight holders can be used much later, making the photographer independent from a near dark room or from carrying a dark tent.

Dry Plates were in available in several standardized plate sizes.