In the last episode, we saw about how Niépce and Daguerre used various techniques like heliography and physautotype to process the images and to make them permanent.
We also saw that after the death of Niépce , Daguerre continued working and found out a new method to process black and white photographs. He named it as “Daguerreotype”. Daguerreotype is the first commercially successful photographic process.
In the 1830’s he found out that copper plates with iodized silver coating will serve as a good base for capturing the images. When he was working further to develop the concept , he accidentally broke his thermometer and he found out that mercury could be used as an agent to develop the invisible image that was previously incident on the silver plates. He face another problem of over darkening of silver which occurred as the result of daguerreotype processing. So he further refined the process and found out that dipping the processed plate in strong salt solution will prevent the image from getting over darkened.
After the development of the complete process and refining it to perfection , he tested it with a camera obscura. The image titled “L’Atelier de l’artiste” was the first successful daguerreotype developed with correct exposure , development and image fixation.
World’s first Daguerreotype L’Atelier de l’artiste
While describing the process in his paper , Daguerre took extensive care to explain each and every step of the process , right from the manufacture of the silver plates. Initially , a special kind of copper coated silver plates called as the Sheffield plates are used for making daguerreotypes. It is produced by rolling two metals together in a roll mill. This will create a thin sheet of copper over which the iodized silver will be coated. Another method called cold-roll cladding was used for making Sheffield plates. In this process , the thin silver foil kept on top of a copper plate and bound together by a metal frame. Then , the plate should be subjected to heat for a tempterature a few points below the melting point of silver. This step is very important because , overheating might fuse both metals and under heating will not complete the process.
After capturing the image on the silver plate, it is subjected to a mercury vapor from a pool of heated mercury. This will help the development of images on the silver plate. This process is called as “Amalgam” which means “fusion”. The plates that are initially developed are less sensitive to light due to the use of silver iodides. In the later years plates are developed with silver halides which are much more sensitive to light than their predecessors. Also the initially used chevalier lenses are replaced with petzval lenses which are made of greater diameter and subsequently decreased the exposure needed for the capture of the image.
After seeing the success of Daguerreotype, Daguerre didn’t keep the invention for himself or patent it to make money out of it. He gave the entire rights of the process to the French government which in turn gave the process as a present to everyone in the world telling that it a gift to the mankind and a way of honoring the lifetime passion of Louis Daguerre towards photography.
Only because of people with such passion and dedication, our world has seen so many great inventions and technological breakthroughs. If we take a moment to think of all these people while holding our camera it will be a great way of respecting science , art and photography.
We will speak more about more about Daguerreotypes and its craze in the coming episodes
[ Image source: Wikipedia ]
To be continued…