Anonymous, 'Unidentified Building'

Anonymous, 'Unidentified Building'

Anonymous
'Unidentified Building'
Possibly in France
About 1840s
Calotype negative
Museum no. 2746-1901

The Photograph

This image is an example of a photograph made with the calotype process. This process, which W.H. Fox Talbot invented in 1840 and patented in 1841, is the direct ancestor of modern photography because it creates a positive image from a negative. Unlike the daguerreotype, a direct positive process, the calotype negative could be used to make multiple prints. The word calotype comes from the Greek 'calos', meaning beautiful.

Identifying the Technique

There are several ways to recognise a calotype negative. The negative image is a deep brown colour on one surface of writing paper. The image becomes part of the paper and contains fine particles of metallic silver, which causes the brown tint to the calotype positive image.

The positive image may have flaws caused by imperfections in the paper used to make the negative image. Calotype images became largely obsolete after the introduction of the collodion process.

The Process

A calotype was made by brushing a silver-nitrate solution onto one side of a sheet of high quality writing paper and drying it. Then, by candlelight, the sheet was floated on a potassium iodide solution, producing slightly light-sensitive silver iodide. The sheet was dried again, this time in the dark. Shortly before taking the photograph, the paper was again swabbed with silver nitrate, this time mixed with acetic and gallic acids. This made the paper very light sensitive.

The sensitised sheet could be used damp in the camera. Damp paper was more sensitive to the light and therefore held a better image. Exposure of ten seconds to ten minutes was necessary, depending on the subject, weather, time of day and intensity of the chemicals employed.

At this point the image was not visible but latent in the paper. To develop the image, the sheet was again dipped in a bath of silver nitrate and acetic and gallic acids. To fix the negative image, now wholly visible, on the paper, the paper was washed in water, then bathed in a solution of bromide of potassium, washed in water again and dried again. The negative was then fixed with a solution of sodium thiosulphate ('hypo'). Sometimes the calotype negative was waxed to improve the transparency and retain more details. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Photographers Who Have Used This Technique

Benjamin Brecknell Turner (albumen prints from calotype negatives)
Calvert Richard Jones
John Dillwyn Llewelyn
D.O. Hill
R. Adamson

 

This photograph can be found in Print Room Box 12.