GELATIN, The introduction of

The development of the Collodion process marked a watershed in the development of photography. However, this wet-plate process had limitations, one being that it was necessary to keep the collodion moist.

For a number of years several attempts were made to discover ways of keeping the collodion moist for long periods. The materials tried included unusual ones like licorice, beer and raspberry syrup! Some success was achieved by using a mixture of bromide in collodion. The ideal binder would be one which enabled the plates to be used only when dry. It was not until 1871 that the next breakthrough was achieved by Dr Richard Leach Maddox, when he began using gelatin.

In fact, as far back as 1850 Robert Bingham had suggested the use of gelatin, but this idea had not been taken up at the time, presumably because of the announcement of the collodion process the following year.

Gelatin is a protein obtained from animals, which is transparent and odourless, and used in a number of food processes. The first account of its use in photography is in the British Journal of Photography for 8 September 1871, when Maddox suggested that the sensitising chemicals could be coated on to a glass plate in a gelatin rather than a collodion emulsion.

Maddox's process, though revolutionary, was far slower than collodion. Several manufacturers experimented with it, the most successful being Charles Bennett, who in 1878 announced a new gelatin dry plate process. This was a major breakthrough, particularly since Bennett's process also considerably enhanced the sensitivity of the emulsion, reducing the exposure time to one tenth of that required for the collodion one.

This dry process

• relieved photographers of the need to carry about their own darkroom and chemicals;
• exposure could now be made on location, development being left until much later;
• it also let to a greater degree of standardisation, and a more scientific approach to photography;
• the science of sensitometry was introduced at around this period, and exposure calculators now began to appear.

By the end of that decade the dry plate had superseded the Wet Plate entirely, and within a further ten years the emulsion could be coated on celluloid roll film.