The silver-plated copper sheet and the blood-protein process
Before the appearance of the dry-plate process, the current photography methods had many drawbacks for photographers. The silver-plated copper sheet photo or daguerreotype – that received its name after Louis Daguerre – was not suitable for multiplication, and the photos taken on paper negatives were not detailed enough. The moment when the French government made Daguerre’s invention public property practically was very important in the history of photography. (The British Empire was an exemption due to a legal dispute.)
“Daguerre introduced the first photograph to the French academy in 1840, where they recognised its great importance immediately. The Parliament satisfied the inventor with a national reward, took over the secret of creation, announced it via newspapers and gave it to the world. Daguerre’s method was: he held a sheet of well-silvered copper above iodine vapour; iodine merged with silver and covered the sheet with iodine silver membrane that is very sensitive to sunlight. He put this prepared plate in darkroom, took it out after 10-15 minutes, and put it above heated mercury vapour in dark. “- Eger, 1866.
The wax coat somewhat vanished the fibrils of paper in the case of paper negative photos, but the sharpness still wasn’t appropriate. Many people thought that the solution for multiplication and quality problems was the application of expensive metals, but the real solution was glass and the glass-plate albumin process that was invented by Abel Niépce de Saint-Victor in 1847.
“The machine, whose glass you stand in front of, is a darkroom. (…) The creation and usage of this tool are based on quite physical laws; but after that the lid is taken off the objective the role of chemical powers starts and lasts until the end.” – Eger, 1866.
This glass-plate albumin process was practical mainly in taking landscape and building photos. It proved to be too time-consuming for portrait photos, because they had to stand in front of the camera for 15 minutes in certain cases in order to get the picture ready. Although the exposure time of the photosensitive material could be shortened by using the plate right after the sensibilization, but the process became more complicated this way. Practically, photographers had to take a mobile laboratory with themselves with tents and different chemicals.
Glass plate with collodion membrane
The wet-plate (or collodion glass-plate negative) process that was invented by Frederick Scott Archer outwent the previous processes both in quality and quickness.
“The photographer (…) takes a clean glass-plate in a dark room, pours it with collodion that evaporates quickly while coating the glass with a thin transparent membrane; and he puts it in silver solution before it dries. The collodion changes immediately, first it was yellowish, now it became opaque, gaining a yellowish-white colour. The photographer puts the still wet plate, which was made sensitive to the world, into the machine, from where he takes it out after some seconds to bring it in his dark workshop. At this time, the picture cannot be seen yet on the collodion membrane (…), but the photographer knows how to gouge the secret out: without any ceremonies, he pours it with an acrid liquid that is green vitriol solution.” – Eger, 1866.
The time of taking a photo was reduced to seconds owing to the new process. Taking a building or landscape photo lasted only 10-90 seconds, and only 20 seconds was enough to take small portrait photos.
“In particular, we recommend the studio of Mr. A. Becske to our dear readers. Recently, he introduced in his atelier the invention that makes photo shooting happen in a moment, and it is so realistic that the success is unsurpassable in this aspect. The momentary photography even makes the photography of the briskest children possible.” – Veszprém, 1881.
Despite recommendations and advertisements, many people insisted on the old silver-plated copper sheet process. The reason for that was the special silvery-gold glitter of the copperplate photos as against the dull grey glass negatives.
Black velvet for background
Due to Peter W. Fry, technical development continued. By improving the wet-plate method, he created the so-called collodion glass positive process (ambrotype) that was originally negative despite its name; it only seemed positive because of the dark background. The negative photos of this method were faded by a chemical process with nitric acid, and then the verso of the glass-plate was covered up with dark varnish, or some black material – for example black velvet – was placed behind it. Its great advantage was that it did not reflect.
The strange patent-rights situation that developed in the case of the daguerreotype became a fortunate circumstance in course of time in the aspect of technology development. As the agreement between Daguerre and the French government did not cover the territory of the British Empire, Daguerre’s agent registered the patent in Britain, in the hope of royalty incomes. Due to this, every British photographer should have paid royalties if using this method, thus the use of daguerreotypes did not spread in Britain. According to science historians, all these could contribute to the fact that the British Talbot elaborated another photography method (talbotype), which could not repeat the world success of the daguerreotype, but became the real predecessor of modern photographic methods, because it allowed the production of paper photos as well.
Translated by Zita Aknai
- A fotográfiai eljárások története: Üveglemez eljárások, (mek.oszk.hu), In Hungarian. (Archived from the original at 27. april 2017.)
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- Híreink. (1881). Veszprém megyei hivatalos heti közlöny, 7 (16), 63. p. (In Hungarian.)
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- A franciák a világnak adományozták a találmányt. (24.hu) 29. december 2018. (In Hungarian.)