Historical Process

Producing a fine photography in late Qing Dynasty China was an exceptional artistic accomplishment. The camera helped to capture the moment, but it was the photographer who orchestrated all aspects of the photograph’s production.

STEP 1

Preparing the Glass Plate

To prepare a glass plate, the photographer ground down the edges of plate glass with oil of turpentine and a fine file. He then carefully cleaned and polished the plate, removing it from the plate-holder and placing it in a grooved plate box. Glass plates were cleaned and polished no more than twelve hours before their use. The possibility of the introduction of dust was too great to allow for any more time than that to lapse between polishing the plate and coating it with collodion.

STEP 2

Coating the Glass Plate with Collodion

Photographic collodion is a mixture of raw cotton treated with nitric and sulfuric acids dissolved in ether and alcohol, with iodide and bromide added.

To make a negative, the photographer poured a puddle of collodion in the center of a clean glass plate and tilted it back and forth until it was evenly distributed. The photographer then drained off and collected the excess collodion for future use.

STEP 3

Sensitizing the Plate

After the glass plate was coated with collodion it was sensitized with silver nitrate in the darkroom or darkroom tent. Silver nitrate binds with iodide and bromide to make a silver halide coating, which is sensitive to light.

STEP 4

PLACING THE GLASS PLATE INTO CAMERA

While still in the darkroom tent, the photographer placed the glass plate in a light-proof holder and inserted the holder in the camera.

STEP 5

EXPOSING THE IMAGE

The photographer removed the lens cap from the camera to expose the plate, allowing the light to enter the camera and strike the light-sensitive collodion.

Exposure times varied from 20 seconds to 5 minutes depending on how fast the silver halides reacted to light, how much light entered through the lens, and the amount of light that hit the subject. The photographer then ended the exposure by placing the lens cap back over the lens. He then removed the light-proof plate holder from the camera and returned it to the darkroom for development.

STEP 6

Pouring on Developer

In the darkroom, the photographer removed the glass plate from, its holder and developed it in a solution of iron sulfate and acetic acid. He then removed the developer by rinsing the glass plate with water. After rinsing, the plate could be safely removed from the darkroom.

STEP 7

FIXING THE IMAGE

The photographer next fixed the image on the plate by placing it in a tray of sodium thiosulfate, which acted as a fixing agent.

STEP 8

WASHING AND VARNISHING THE NEGATIVE

The photographer again rinsed the glass plate, this time to remove the fixing agent before it dried.

To protect the negative, he applied a coat of varnish to the plate. After warming a bottle of varnish and the plate over a flame, the photographer coated the glass plate with varnish on the emulsion side of the plate.

A visible negative image appears on the plate.

STEP 9

Printing a Photograph

To make an albumen print from a collodion negative, a sheet of paper was floated on a solution of frothy albumen (egg white) that contained a chloride and then dried. Next the paper was floated on a solution of silver nitrate and dried again. Then the paper was placed in the printing frame with the negative aligned over the paper. Both were then placed in direct sunlight. The sun and atmosphere of China printed the picture. The print was then washed in water and then possibly toned in gold chloride and washed again. Sodium thiosulfate fixed the print before it was given its final wash.