The Daguerreotype Photographic Process 19 August

On this day, August 19 in 1839, the French Government acquired the patent of the daguerreotype photographic process. The process is named after its inventor, French artist and chemist Louis J.M. Daguerre. The French Government announced the invention as a gift "Free to the World." - apart from the English, from whom the patent was withheld - this was, after all, before the Entente Cordial!

The daguerreotype is a type of photograph, but, unlike modern photographs, it has no negative. Instead, it is an image exposed directly onto a mirror-polished surface of silver, (which has first been exposed to iodine vapour), housed in a velvet-lined folding case. While the daguerreotype was not the first photographic process to be developed, it had the advantage over earlier processes, in which the images tended to fade quickly when exposed to light. The daguerreotype became the first commercially used photographic process - and jolly clever it was too.

However, just because it was jolly clever didn't mean that that was the end of it. The process was only used for about 10 years before being overtaken by, amongst others, the Ambrotype introduced in 1854, which gave a positive image on glass, with a black backing, the Tintype or Ferrotype, which produced an image on chemically-treated tin and the albumen print, a paper photograph produced from large glass negatives that was most commonly used in American Civil War photography.

The swift disappearance daguerreotype photography was inevitable because the process is intricate and complex. Not only that, it was also labour intensive, and involves multiple stages of production. As a result, daguerrotypes were expensive. Worse still, the typical exposure was often 60 to 90 seconds long, requiring the sitter to hold a pose for all that time. Additionally, since there is no negative, it had images could not later be reproduced. Finally, and probably most damning of all, let's not forget - it is a French invention. Nevertheless, French or not, unlike film and paper photography, a daguerreotype, when properly sealed, can last virtually forever.