T wo types of glass negative processes, dry- and wet-plate collodion, were utilized in the photographs featured. The wet-plate, or wet collodion, process was used from 1851 through the 1880s and required the plates be processed within minutes of exposure before the coating dried. The dry-plate process gained popularity in the 1870s after Richard Leach Maddox suggested silver bromide held in a layer of gelatin for coating dry plates and simplified the process and were produced in large numbers within the decade(1).
Dry Plate Process(2)
•Place the dry plate into a plate holder then into a camera
•Slide the cover from the plate holder to uncover the plate
•Uncover then recover lens (sometimes a fraction of a second of exposure was enough)
•Slide plate cover hold back over the dark slide
•Remove plate holder from camera and take home to process
Polishing the Plate
The photographer cleaned and polished the plate in the beginning stages of processing to prepare plate for "bath" in silver nitrate solution to sensitization to light.
Coating the Plate
Plates were coated in materials such as iodides and bromides before being placed in a silver nitrate bath for sensitization.
Sensitizing the Plate
After preparation, the plate would be placed within a holder for use wiht the camera, soon to be exposed for a photo.
Developing the Plate
Once the image was captured the treatment had to be done quickly as it was required for the image to be developed before the coating dried.
Wet Plate Process(3)
•Dissolve ether to produce collodion (alcohol also required)
•Add bromides and iodides to mixture and coat one side of plate
•Sensitize the glass plate in a “silver bath”
•Transfer the plate to a plate holder then the holder into the camera
•Take photo while coating is wet, an exposure of several seconds required
•Develop the wet negative
•Fix in hypo/cyanide solution, rinse, and dry
•Coat with a varnish to help protect the collodion layer
•Lay negative over albumen paper and expose to light
•Treat with gold chloride to prevent fading
Below is a video of HCSCC Archivist Mark Peihl taking viewers through the Wet Plate proccess.
1. EdinPhoto, "Early Photographraphic Processes, Dry Plates," <http://www.edinphoto.org.uk/1_early/1_early_photography_-_processes_-_dry_plates.htm>, (accessed 4 November 2017).
2. EdinPhoto, "Early Photographraphic Processes, Dry Plates," <http://www.edinphoto.org.uk/1_early/1_early_photography_-_processes_-_dry_plates.htm>, (accessed 4 November 2017).
3. EdinPhoto, "Early Phographic Processes, Wet Collodion Process, 1851-1880s," <http://www.edinphoto.org.uk/1_early/1_early_photography_-_processes_-_wet_collodion.htm>, (accessed 4 November 2017).