A team of interdisciplinary scientists at the University of Western Ontario recovered missing images from the 19th century using modern x-ray technology.
The photos showed black and white images of a man and a woman, but the quality has already deteriorated. The daguerreotype is the earliest technique in photography which dates back to 1850.
The team used micro x-ray fluorescence imaging that can see through the tiny particles of a projected photo. The x-ray beam reacts to the mercury properties of the photographs, and the total process took about eight hours.
"The image is totally unexpected because you don't see it on the plate at all. It's hidden behind time," said lead author Madalena Kozachuk, who is also a Ph.D. student at the university's department of chemistry. "But then we see it and we can see such fine details: the eyes, the folds of the clothing, the detailed embroidered patterns of the tablecloth."
More details of the study are published in the June 22 edition of the journal Scientific Reports.
What Takes Place In Daguerreotype Photography?
The silver-coated copper plates used in daguerreotype become sensitive to light when they are exposed to iodine vapor. Subjects have to stay still for about three minutes until the image is imprinted on the plate. The photograph is then developed using the heated mercury vapor.
"An ancillary step was added two years later by Fizeau that involved pouring a gold-chloride-sodium thiosulfate solution over the plate, which was heated from below. This deposited gold on the image surface via an electroless deposition process," the authors wrote.
Co-author Ian Coulthard, who is a fellow at the Canadian Light Source, said the damage sustained on the daguerreotype plates are the combination of corrosion and cloudiness from the residue during production.
Tsun-Kong Sham, co-author and the university's Canada Research Chair in Materials and Synchrotron Radiation, said that the image particles in the retrieved photographs remained intact even when the surface of the plates is tarnished.
Significance In History
John McElhone of the Canadian Photography Institute of National Gallery of Canada said the study would help conservators to understand the material on a nanoscale level. Historians believe that daguerreotypes are the first "true" visual representations because it shows exactly what is photographed.
Their findings will pave the way to improve recovery techniques for daguerreotype images. At the same time, experts can find ways to see the images when cleaning is impossible.
