The Glass Plate

The early beginnings of photography can be traced back to an invention in 1851 by Frederick Scott Archer. Scott developed a method of sensitizing glass plates with silver salts by the use of collodion. This method completely replaced the daguerreotype and calotype process and remained popular until 1880.


I have chosen to cover the glass plate era as I had a few glass plates in my photographic collection. The glass plate can be traced back to an invention in 1847, where egg whites were used. The major drawback of albumen plates was their low sensitivity. The significant advantage of the time was that they could be made in advance and exposed months later. The most significant disadvantage was that they were not very sensitive, sometimes requiring exposures of up to three hours for well-lit subjects.

Images achieved from glass negatives.

The collodion used to coat the glass plate made from a solution of nitrocellulose in alcohol and ether described as being rather vicious. It quickly dried to form a tough, waterproof film. Archer added potassium iodide and then coated a glass plate with it. Then in the dark or subdued light, he dipped the plate in a solution of silver nitrate. The silver ions combined with the iodide ions to form light-sensitive silver iodide within the collodion. He then exposed the wet plate in the camera after which it was developed in pyrogallic acid, fixed in hypo, washed and then finally dried. All these operations had to be completed very rapidly before the collodion dried and became impervious to the processing solutions.

One of the drawbacks was the photographer always had to be close to a darkroom or take the darkroom with him. The darkroom was usually a wagon or a tent equipped with all the chemicals and processing equipment. Other than the actual time it took to expose the plate the photographer had to begin by polishing the plate then coating the plate, followed by sensitizing the plate and finally ended off by developing and fixing the plate.


Frederick Scott Archer’s wet camera 1851