COLLODION process, The

This process was introduced in 1851 and marks a watershed in photography.

Up till then the two processes in use were the daguerreotype and the calotype. Daguerreotypes were better than calotypes in terms of detail and quality, but could not be reproduced; calotypes were reproducible, but suffered from the fact that any print would also show the imperfections of the paper.

The search began, then, for a process which would combine the best of both processes - the ability to reproduce fine detail and the capacity to make multiple prints. The ideal would have been to coat light sensitive material on to glass, but the chemicals would not adhere without a suitable binder which obviously had to be clear. At first, Albumen (the white of an egg) was used. Then in 1851 Frederick Scott Archer came across collodion.

Collodion was a viscous liquid - guncotton dissolved in ether and alcohol - which had only been invented in 1846, but which quickly found a use during the Crimean war; when it dried it formed a very thin clear film, which was ideal for dressing and protecting wounds. (One can still obtain this today, for painting over a cut). Collodion was just the answer as far as photography was concerned, for it would provide the binding which was so badly needed. Lewis Carroll, himself a photographer who used collodion, described the process in a poem he called "Hiawatha's Photography."

"First a piece of glass he coated
With Collodion, and plunged it
In a bath of Lunar Caustic
Carefully dissolved in water;
There he left it certain minutes.
Secondly my Hiawatha
Made with cunning hand a mixture
Of the acid Pyro-gallic,
And the Glacial Acetic,
And of alcohol and water:
This developed all the picture.
Finally he fixed each picture
With a saturate solution
Of a certain salt of Soda...."

This "soda" was, of course, hypo. Sometimes potassium cyanide was used, the advantage of this being that the solutions could be washed out by rinsing under a tap for a minute or so, whereas hypo would need much more washing time.

The collodion process had several advantages.

  • being more sensitive to light than the calotype process, it reduced the exposure times drastically - to as little as two or three seconds. This opened up a new dimension for photographers, who up till then had generally to portray very still scenes or people.
  • because a glass base was used, the images were sharper than with a calotype.
  • because the process was never patented, photography became far more widely used.
  • the price of a paper print was about a tenth of that of a daguerreotype.

There was however one main disadvantage: the process was by no means an easy one. First the collodion had to be spread carefully over the entire plate. The plate then had to be sensitised, exposed and developed whilst the plate was still wet; the sensitivity dropped once the collodion had dried. It is often known as the wet plate collodion process for this reason.

The process was labour-intensive enough in a studio's darkroom, but quite a feat if one wanted to do some photography on location. Some took complete darkroom tents, Fenton took a caravan, and it is no mere coincidence that many photographs taken in this period happened to be near rivers or streams! Moreover, at this time there were no enlargements, so if one wanted large prints, there was no alternative but to carry very large cameras. (It is such limitations of the process that make the work of people like the Bisson brothers, Fenton, and others so remarkable).

One might also mention the safety factor. The collodion mixture was not only inflammable but highly explosive. It is reported that several photographers demolished their darkrooms and homes, some even losing their lives, as a result of careless handling of the photographic chemicals.

Despite the advantages the collodion process offered, there were still many who stoutly defended the calotype. A writer in the Journal of the Photographic Society (December 1856) wrote:

"for subjects where texture, gradations of tint and distance are required, there is nothing.... to compare with a good picture from calotype or waxed paper negative."

Moreover, the calotype process was less of an ordeal, especially for travel photographers; paper negatives could be prepared at home, exposed on location, and then developed upon one's return. Hence Diamond used the calotype process for some of his travel photographs, though he used collodion for portraiture and for his medical photography.

Nevertheless the invention of this process turned out to be a watershed as far as photography was concerned:

The use of collodion caught on very quickly indeed, and within a few years few people used either the Daguerreotype or Calotype process.

The records of the Photographic Society give an interesting account of the efforts to ensure even sensitivity of the Collodion plates. As mentioned above, these plates had to be dipped into a nitrate of silver bath and exposed whilst still wet. Exposure would have to be almost immediate as otherwise the top of the plate would lose its moisture and the sensitivity would become uneven. All sorts of liquids were tried, including honey, beer, and even rasperry syrup!

A variation on this was the Oxymel process.

To see a short video clip showing a collodion plate being made, see HERE.

© Robert Leggat, 2001