Study Room resource: Processes and techniques of photography

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.

Calvert Jones, 'View of Unidentified Harbour'

Calvert Jones
'View of Unidentified Harbour'
1844-6
Salt paper print
Museum no. PH.43-1983

The Photograph

This image is an example of a salt print. Salt prints, the earliest paper prints, were normally made by contact printing, usually from paper negatives (calotypes) but occasionally from collodion negatives on glass. Invented by W.H. Fox Talbot in 1840, salt prints were a direct outgrowth of his earlier photogenic drawing process.

Identifying the Technique

A finished salt print is matt in tone, reddish brown in colour, and has no surface gloss. If toned it is purplish brown; if faded, yellowish brown. Its highlights are usually white. Salt prints were made until about 1860, although in decreasing numbers after the advent of the albumen print in 1851.

The Process

A salt print was made by sensitising a sheet of paper in a solution of salt (sodium chloride) and then coating it on one side only with silver nitrate. Light-sensitive silver chloride was thus formed in the paper. After drying, the paper was put sensitive side up directly beneath a negative under a sheet of glass in a printing frame. This paper-negative-glass sandwich was exposed glass side up, outdoors in sunlight, i.e. it was contact printed.

The length of the exposure, up to two hours, was determined by visual inspection. When the print had reached the desired intensity it was removed from the frame and fixed with sodium thiosulphate, at that time called hyposulphate of soda ('hypo'), which stopped the chemical reaction. It was then thoroughly washed and dried. The print could be toned with gold chloride for greater permanence and richer tone. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Photographers Who Have Used This Technique

W .H. Fox Talbot
D.O. Hill
R. Adamson

This photograph can be found in Print Room Box 12.

Philip H. Delamotte, 'Crystal Palace'

Philip H. Delamotte (1820-89)
'Crystal Palace'
1854
Albumen print, from a wet collodion negative
Museum no. 39.294

The Photograph

This image is an example of an albumen print made from a wet collodion negative. The albumen print was invented by Louis-Désiré Blanquart-Evrard (1802-72), and until about 1890 it was the most prevalent type of print.

Identifying the Technique

This photograph can be identified as an albumen print by the slight sheen on the top surface. An albumen print can sometimes be identified as being produced from a wet-collodion negative.

The easiest way to do so is to find white dots on the print (such as those in the lower right corner of this image), where dust or other impurities have stuck into the collodion. Occasionally, when the collodion has been poured unevenly onto the glass plate, the print can appear streaky, reflecting the varying thickness of the collodion. The collodion process produces crisp, grainless prints that have more detail than the calotype and generally have a much richer tone.

The Process of an Albumen Print

An albumen print was made by floating a sheet of thin paper on a bath of egg white containing salt, which had been whisked, allowed to subside, and filtered. This produced a smooth surface, the pores of the paper having been filled with albumen. After drying, the albumenised paper was sensitised by floating it on a bath of silver nitrate solution or by brushing on the same solution. The paper was again dried, but this time in the dark. This doubly coated paper was put into a wooden, hinged-back frame, in contact with a negative, usually made of glass but occasionally of waxed paper.

After printing, which sometimes only required a few minutes but could take an hour or more, the resultant proof, still unstable, was fixed by immersing it in a solution of hyposulfite of soda ('hypo') and water and then thoroughly washed to prevent further chemical reactions. The print was then dried. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

The Process for a Wet Collodion Negative

The wet collodion process was invented in 1848 by F. Scott Archer (1913-57) and published by him in 1851. It was prevalent from 1855 to about 1881. Wet-collodion-on-glass negatives were valued because the transparency of the glass produced a high resolution of detail in both the highlights and shadows of the resultant prints and because exposure times were short, ranging from a few seconds to a few minutes, depending on the amount of light available.

Collodion is guncotton (nitrocellulose) dissolved in ethyl alcohol and ethyl ether. In the wet-collodion process, collodion was poured from a beaker onto a glass plate tilted to quickly produce an even coating. When the collodion had set but not dried, the plate was made light sensitive by bathing it in a solution of silver nitrate, which combined with the potassium iodide in the collodion to produce light-sensitive silver iodide. The plate in its holder was then placed in the camera for exposure while still wet - hence the name of the process. After exposure the plate was immediately developed in a solution. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Photographers Who Have Used This Technique

Julia Margaret Cameron (albumen prints from wet collodion negatives)
Benjamin Brecknell Turner (albumen prints from calotype negatives)
Charles Thurston Thompson (albumen prints from wet collodion negatives)
Francis Frith
Clementina, Lady Hawarden

This photograph can be found in Print Room Box 12.

Kellogg, 'Still Life'

Kellogg
'Still Life'
About 1900
Platinum print
Museum no. PH.354-1980

The Photograph

This image is an example of a platinum print.
The process for making platinum prints was invented in 1873 by William Willis (1841-1923), who continually refined it until 1878, when commercially prepared platinum papers became available through a company he founded.

Identifying the Technique

Platinum prints are recognised by their subtle tonal variations and the permanence of the image. This print shows the silvery grey tones (the most usual colours of the platinum print) and the texture of the paper, which are typical qualities of a platinum print.

The Process

The process depends on the light sensitivity of iron salts. A dried sheet of paper, sensitised with a solution of potassium chloroplatinate and ferric oxalate, an iron salt, was contact printed under a negative in daylight (or another source of strong ultraviolet light) until a faint image was produced by the reaction of light with the iron salt.

The paper was developed by immersion in a solution of potassium oxalate that dissolved out the iron salts and reduced the chloroplatinate salt to platinum in those areas where the exposed iron salts had been. An image in platinum metal replaced one in iron. The paper was washed in a series of weak hydrochloric or citric acid baths to remove remaining excess iron salts and yellow stain formed in the earlier steps. Finally, the print was washed in water.

Platinum prints were popular until the 1920s when the price of platinum rose so steeply as to make them prohibitively expensive. They were partly replaced by the somewhat cheaper palladium prints. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Photographers Who Have Used This Technique

Pradip Malde
Irving Penn
Paul Martin
Frederick Evans
Frederick Hollyer 

This photograph can be found in Print Room Box 12.

(top) Lewis Hine, 'Messenger Boy'

Lewis Hine 
'Messenger Boy' (top)
Texas
1913
Gelatin-silver print
Museum no. PH.46-1977

'Boys Going to Work' (bottom)
Rhode Island
1909
Gelatin-silver print
Museum no. PH.44-1977

The Photograph

In 1871, the gelatin dry plate was introduced. This process used a sensitised gelatin emulsion that was dried on the plate and could be stored, protected from light, for months before use. The gelatin process superseded the wet collodion process and revolutionised the world of photography.

In 1873 gelatin-silver bromide papers were invented and first produced by Peter Mawdsley, although they did not come into general use until the 1880s.
They were developing-out rather than printing-out papers, that is, after a brief exposure under a negative, usually in an enlarger, the image was further brought out by chemical development.

Identifying the Technique

Because of the great variety of papers offered by manufacturers, the tones and surface gloss of gelatin prints varied. Generally, however, the tone of the image of the gelatin-silver-bromide print is neutral black. A gelatin-silver-chloride print that has been developed out is blueish or cool in tone, while one that has been printed out is brown or warm in tone. All of these colours can be altered by toning.

The highlights are white unless the underlying paper support has been tinted. Gelatin-silver prints often have a high surface gloss, particularly if they are contact prints. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Both these photographs are gelatin-silver prints, their cool tones suggesting that they are developed-out prints. Note that both prints have a glossy surface, typical of most gelatin-silver prints, but the lower image is more shiny, showing that the gloss can vary in strength between prints.

The Process

Although the gelatin print is usually a developing-out process - that is, after a brief exposure to a negative, the print is immersed in chemicals to allow the image to develop - it can also be a printing-out process, similar to the albumen process.

Gelatin, an animal protein, is used as an emulsion to bind light-sensitive silver salts - usually silver bromides or silver chlorides - to a paper or other support. Depending on the type of salts used, silver chloride for printing-out and silver bromide for developing-out, the photograph was placed under the negative under a light until the image appeared in its final form, without chemical development, or exposed under a negative and then immersed in chemicals to allow the image to develop or emerge. The first process, printing-out, was necessarily much longer than for a developed-out photograph.

Photographers from the 1880s and afterward did not normally coat their own papers but obtained them from commercial sources. Gelatin-silver prints had generally displaced albumen prints in popularity by 1895 because they were more stable, did not yellow, and were simpler and quicker to use. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Photographers Who Have Used This Technique

Ansel Adams
Bill Brandt
Edward Weston
David Bailey
Frederick Sommer

This photograph can be found in Print Room Box 12.

Paul Martin, 'Seascapes'

Paul Martin
'Seascapes'
Britain
About 1890s
Carbon print
(top row from left to right) Museum no. PH.346-1980, PH.342-1980, PH.341-1980
(bottom row from left to right) Museum no. PH.332-1980, PH.338-1980, PH.345-1980

The Photograph

Carbon printing was most popular between 1870 and 1910 but is still sometimes used today. These images are an example of the technique.
Although patented in 1855 by Alphonse Louis Poitevin (1819-82) and improved in 1858 by John Pouncy (1818-94), carbon prints only became fully practicable in 1864, with the patented process and printing papers of Joseph Wilson Swan (1828-1914).

Identifying the Technique

The prints show dense, rich, glossy tones that are either black or a deep brown in colour. Various pigments could be used to give access to a greater range of colours and the prints show slight relief contours (thickest in the darkest areas) as a result of the process used. The most important feature of a carbon print is its permanence; it contains no silver impurities that can deteriorate.

The Process

The main principle of the process is the fact that gelatin (to which potassium bichromate has been added) becomes insoluble when exposed to light, in proportion to the amount of light received. A sheet of lightweight paper was coated with gelatin containing potassium bichromate and a pigment.

In daylight this tissue was placed under and in contact with a negative. This exposure was timed, as the dark-coloured paper did not show an emerging image. Those parts of the gelatin that were exposed to light through the negative hardened.

In order to wash away the unhardened gelatin and reveal the image, the face of the exposed carbon tissue was squeezed in contact with a second sheet of paper coated with an insoluble gelatin layer, thus forming a sort of gelatin sandwich which was then soaked in warm water. The paper floated free and the unhardened gelatin was washed away, leaving the image attached to the second sheet. The sheet was then immersed in water containing alum (which) hardened the remaining gelatin and removed any yellowish bichromate stains. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Photographers Who Have Used This Technique

John Thomson (woodburytypes - a photomechanical version of carbon printing)
W.J. Day
Herbert Ponting

This photograph can be found in Print Room Box 12.

Anonymous, 'Portrait of Three Unidentified Girls'

Anonymous
'Portrait of Three Unidentified Girls'
About 1860s
Collodion positive
Museum no. E.1163-1992

The Photograph

Collodion positive was invented by F. Scott Archer in 1822 and was in widespread use by the mid 1850s. It is also sometimes called an ambrotype.

Identifying the Technique

This portrait can be identified as a collodion positive because the image is always shown as a positive unlike the daguerreotype where both the positive and negative images are visible depending on the lighting of the object.

The Process

A sheet of glass was hand-coated with a thin film of collodion (guncotton disolved in ether) containing potassium iodide, and was sensitised to the light with silver nitrate to create a collodion negative. The back is painted black or covered with a piece of black cardboard or cloth in order to achieve the effect of a positive image.

Photographers Who Have Used This Technique

George Ruff
Stephen Gray
William Hall

This photograph can be found in Print Room Box 12a.

Arthur E. Cope, 'Portrait of the Photographer's Children'

Arthur E. Cope
'Portrait of the Photographer's Children'
About 1910
Autochrome
Museum no. E.2-1995

The Photograph

The autochrome was the first viable colour photograph process. It was introduced by the Lumier brothers in 1905 but not marketed until 1907.

Identifying the Technique

Due to the presence of  microscopic grains of potato starch, dyed red, green and blue, the image shows a grainy quality.

The Process

An autochrome was a coloured, transparent image on glass, similar to a slide. The colour came from a layer of translucent granules of potato starch, each dyed red, blue or green to create a coloured mosaic on the glass plate. During exposure, light travelled through these granules to reach a light sensitive layer below; red granules would only allow re light to travel through, and so on. The light sensitive layer was thus selectively exposed by colour. When the autochrome was held up to the light, the coloured granules were viewed in combination with the black and white image behind to create a colour photograph.

Although autochrome was not the first colour process for true photography, it was the first to be widely and commercially available.

This photograph can be found in Print Room Box 12a.

Anonymous, 'Portrait of Two Unidentified Women'

Anonymous
'Portrait of Two Unidentified Women'
About 1850
Daguerreotype
Museum no. PH.167-1929

The Photograph

This image is an example of the daguerreotype.
The daguerreotype was invented by Louis-Jacques-Mandé Daguerre and introduced to the public at a meeting of the French Academy of Sciences in Paris on August 19, 1839.

Identifying the Technique

The daguerreotype image was easily damaged by touching, and was protected in a case or frame, with a decorative mask or matt and a cover glass.

Since the image is in the form of a greyish-white deposit on a shiny silver surface, the daguerreotype has to be held so as to reflect a dark ground against which the image is seen as a positive. If the image reflects a light ground, the image appears negative. This is unique to the process and is the most easily recognised feature when the daguerreotype is in a case.

The Process

The daguerreotype is a direct-positive process, creating a highly detailed image on a sheet of copper plated with a thin coat of silver without the use of a negative. Highly polished silver-plated copper sheets are treated with iodine to make them sensitive to light. After they are exposed in a camera, the sheets are developed with warm mercury vapor until the image appears. To fix the image, the plate was immersed in a solution of sodium thiosulfate or salt and then toned with gold chloride.

Exposure times for the earliest daguerreotypes ranged from three to fifteen minutes, making the process nearly impractical for portraiture. Modifications to the sensitization process coupled with the improvement of photographic lenses soon reduced the exposure time to less than a minute.

Photographers Who Have Used This Technique

Robert Cornelius
Matthew Brady
Henry Mayhew

This photograph can be found in Print Room Box 12a.

P.H. Emerson, 'The Haysel'

P.H. Emerson
'The Haysel'
About 1887
Photogravure
Museum no. E.3195-1990

The Photograph

This image is an example of the photogravure technique. Photogravure, also known as heliogravure, is arguably the finest photomechanical means for reproducing a photograph in large editions. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Photogravure was devised by the Austrian printer Karel Klic (1841-1926) in 1879 and further developed by him.

Identifying the Technique

The photogravure can be distinguished from other photomechanical printing processes by the lack of any regular or well defined structure, which can be seen in the subtle gradation of tones in this image.

The Process

The photogravure process depends on the principle that bichromated gelatin hardens in proportion to its exposure to light. A tissue coated on one side with gelatin sensitised with potassium bichromate was exposed to light under a transparent positive that had been contact printed from the negative of the image to be reproduced.

When wet, this tissue was firmly pressed, gelatin side down, onto a copper printing plate that had been prepared with a thin, even dusting of resinous powder. In warm water, the tissue-paper backing was peeled away and those areas of the gelatin that had not been exposed to light dissolved. The copper plate with its remaining unevenly distributed gelatin coating was then placed in an acid bath.

Where the gelatin remained thick (the highlights of the print to come) the acid ate away the metal slowly; where the gelatin was thin or absent, the acid bit faster. The plate was thus etched to different depths corresponding to the tones of the original image. When inked, the varying depths held different amounts of ink. The inked plate was then used in a printing press. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991

Photographers Who Have Used This Technique

Frederick Evans
Thomas Annan
Alvin Langdon Coburn

This photograph can be found in Print Room Box 12.