The Calotype was a positive/negative process which was introduced in 1841 by a man named Henry Fox Talbot. It was also known as the Talbotype, or salted print processing. Although it was never as popular as other photographic processes, such as the daguerreotype, it was very popular with artists, amateurs as scientists as it was printed on paper, so was easier to examine and touch up, and multiple prints could be made from the negative. It was not very popular among serious photographers however as the materials were less sensitive to light, resulting in longer exposures, and the process took longer as it required two stages (making the negative and the positive).
The Calotype is made using iodized paper, rather than glass or film which is a more conventional medium.
The paper was carefully chosen and was more commonly high quality writing paper. The paper was then painted with a solution of silver nitrate and then dried, it was then soaked in a solution of potassium iodine and rinsed and dried again. This was all conducted in candlelight so to not expose the paper.
Right before taking the photograph the paper was then coated with a solution of gallo-nitrate silver and was partially dried. The paper was then loaded into a camera and exposed to the chosen scene. The exposures took anywhere from 10 seconds to 10 minutes.
After the paper has been exposed, it is developed using gallo-nitrate silver again, and then fixed. This completes the negative process of the Calotype.
In order to produce a positive, the negative is placed on top of photo paper and placed in a glass frame under direct sunlight. After a certain amount of time, the paper is then developed and fixed and a positive image is reproduced.
The Calotype is made using iodized paper, rather than glass or film which is a more conventional medium.
The paper was carefully chosen and was more commonly high quality writing paper. The paper was then painted with a solution of silver nitrate and then dried, it was then soaked in a solution of potassium iodine and rinsed and dried again. This was all conducted in candlelight so to not expose the paper.
Right before taking the photograph the paper was then coated with a solution of gallo-nitrate silver and was partially dried. The paper was then loaded into a camera and exposed to the chosen scene. The exposures took anywhere from 10 seconds to 10 minutes.
After the paper has been exposed, it is developed using gallo-nitrate silver again, and then fixed. This completes the negative process of the Calotype.
In order to produce a positive, the negative is placed on top of photo paper and placed in a glass frame under direct sunlight. After a certain amount of time, the paper is then developed and fixed and a positive image is reproduced.
View of the Botanic Gardens, Oxford, by W. H. Fox Talbot, 30th July, 1842.
Salted paper print of an unknown man by Robert Adamson, mid 1840s.
References
-Wikipedia, Calotype, http://en.wikipedia.org/wiki/Calotype, viewed 9 Aug 2009
-A History of Photography, The Calotype process, http://www.rleggat.com/photohistory/history/calotype.htm, viewed 9 Aug 2009
-University of Glasgow, The Calotype process, http://special.lib.gla.ac.uk/hillandadamson/calo.html, viewed 9 Aug 2009
-University of Oxford, Calotypes, http://www.mhs.ox.ac.uk/features/ephotos/ctypes.htm, viewed 9 Aug 2009
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