A Very Brief Description
· Prepare a sheet of copper that has been electroplated with a coating of metallic silver (The Sheffield Process) and buff it to fine shine.
· Place the metal plate in a light tight box (an iodizing box) that contains iodine. In the box the plate will absorb the fumes of the iodine, which will react with the silver, turn orange and result a light sensitive silver iodide coated plate.
· In a low light environment, load the sensitized plate into a camera and expose it to a subject in bright sunlight. This exposure will average about 15 to25 minutes.
· Next, develop the plate with the fumes of mercury that has been heated to 140° F. During this stage, conducted in the very low light, the mercury will merge (amalgamate) with the silver in the exposure’s highlights.
· Finally, the plate is washed with a diluted solution of sodium thiosulfate (originally sodium chloride; Daguerre 1837) and washed with water. The shadows of the image are plain polished silver and the highlights are a pale white amalgam created by the mercury’s effect upon the silver during development. Once dried, it is permanent.