Taylor Made: Metallic photographs
In 1837, at a time when the country’s population was spreading to the west, Louis Jacques Mandé Daguerre successfully printed an image on a sheet of silver-plated copper. Two years later, the Dagurreotype became the first publicly available method for printing photographs.
Photographers would polish the sheet to a mirror-like finish and expose it first to chloride of iodine and next chloride of bromine fumes. All chemical exposures were performed inside a closed container. The reaction of the chemicals with the silver plating created a light-sensitive material— silver iodide (AgI) and silver bromide (AgBr) are both inorganic, highly photosensitive compounds.
The treated sheet was then temporarily covered with a light-proof holder so that it could be placed inside the camera without being ruined by light. To actually take the photo, the camera’s lens cap was removed. Light passing through the lens was focused onto the sheet in much the same way that analog film captures images today.
But unlike analog film, the sheet needed to be exposed to light for a significant amount of time. The photo’s subject was required to remain motionless for the duration of the exposure, which could take up to half an hour for large plates.
After taking the photograph, the plate had to be exposed to mercury fumes to create a clear image and bathed in sodium thiosulfate (Na2S2O2xH20) to make the image permanent.
The Daguerreotype’s surface was still fragile after treatment and scratches to the metal surface could permanently mar the image. One method for strengthening the photo was to treat the plate with gold chloride (Au2Cl6). Finished Daguerreotypes could also be painted with powder pigments to become colorized.