SHOOTING FORMATS #0.3: AgNO3 & Daguerreotype
Niépce then began experimenting with silver compunds based on the German Professor, Johann Heinrich Schultz’s discovery in 1727, that silver nitrate (AgNO3) darkens when exposed to light. (a joke to remember this chemical expression is – Does accepting not knowing how photography works make you an AgNO3-stic) The reactive silver nitrate is nasty on human skin, creating an irritable discolouration. However excessive Colloidal Silver can be used to stain a humans insides – which is why this man turned blue…
In partnership, Niépce and Louis Daguerre (in Paris) refined the existing silver process. In 1833 Niépce died of a stroke, leaving his notes to Daguerre.
While he had no scientific background, Daguerre made two pivotal contributions to the process. He discovered that exposing the silver first to iodine vapour before exposure to light, and then to mercury fumes after the photograph was taken, could form a latent image.
Bathing the plate in a salt bath then fixed the image.
On January 7, 1839 Daguerre announced that he had invented a process using silver on a copper plate called the daguerreotype, and displayed the first plate. The French government bought the patent and, on August 19th of that year, made it public domain.
Leading to this image of Paris, where the long exposure meant the only people who stopped long enough on the busy street to become recorded, was a shoe shiner and shinee…