The advantages of easy duplication brought by the paper negative were to some extent outweighed by its disadvantages. The paper fibres imparted a distinct mottle to the print even when the negative had been waxed - limiting the resolution of fine detail. It was realized that the problem would not exist if glass could be used as a support for the sensitive material. However, since glass was not absorbent like paper, a suitable coating had to be found to carry the light-sensitive salts.
Albumen
Sir John Herschel made an image on glass in 1839 by precipitating silver chloride onto a glass plate in a process which took several days of preparation. For this reason, it was not a practical process, although a picture taken by Herschel in September 1839 is preserved in the Science Museum, London. The first generally successful glass-plate process was introduced in 1847 by Abel Niépce de Saint-Victor, a cousin of Nicéphore Niépce. He found that egg white - albumen - coated on glass provided a suitable medium for sensitive salts. A carefully cleaned glass plate was coated with a solution of potassium iodide mixed with albumen. When dry the plate was sensitized when required with an acidified silver nitrate solution. The exposed plate was developed with gallic acid. The albumen plate was very insensitive but had exceptional resolving power, particularly valuable in architectural photography. Albumen plates were also used for making lantern slides for projection and, later, for transparencies for stereoscopes.
Collodion
In March 1851 Frederick Scott Archer, an English sculptor and Calotype photographer, described a new process using collodion in ‘The Chemist’. He was not the first person to consider the use of collodion for photographic purposes - Robert Bingham suggested its use in his 1850 book ‘Photogenic Manipulation’, and Gustave Le Gray published his formulas for its use in his 1850 paper on photographic methods on paper and glass. However, while these publications were mainly theoretical, Archer introduced actual working examples of the process when he detailed his findings.
Collodion had been recently developed as a medical dressing in 1846 and made by dissolving a form of gun-cotton in ether. The resultant viscous and transparent liquid could be used as a surgical dressing and to hold bandages in place. Archer’s process involved combining a quantity of collodion containing potassium iodide and pouring it onto a perfectly clean glass plate. By tilting the plate the collodion was made to flow evenly over the surface. When the ether had almost evaporated, leaving a clear gelatinous coating, the plate was plunged into a bath of silver nitrate to sensitize it. The still-wet plate was loaded into a plateholder and exposed in the camera; if left to dry, almost all its sensitivity was lost. Immediately after exposure the plate was developed, fixed and washed. The collodion negative could record fine detail and subtle tones and had the great advantage of being much more sensitive than either the Daguerreotype or Calotype processes.
Ambrotype
In a book published in 1852, Scott Archer described a variation of his process in which the collodion negative was whitened by treatment with a solution of mercuric bichloride. If the image were backed with black varnish, paper or velvet, by reflection the negative image appeared positive. The collodion positive, or Ambrotype as it was known commercially in America, soon became very popular for portraiture. Unlike the Daguerreotype process, it required little skill and a very modest investment in apparatus and materials. No licences were needed for its commercial operation and images were cheap to produce. Archer was notably very generous in detailing the chemical formulas and procedures to use in his process. Unlike Talbot, he never sought to patent his work (in fact, Talbot filed numerous suits against photographers using the collodion process, claiming it violated his calotype patents, but these claims were finally dismissed by the Talbot vs Laroche case in 1854). Archer’s ready encouragement of the photographic community to adopt his process, combined with its technical superiority over daguerreotypes and calotypes, led to its rapid adoption as the photographic method of choice for the next 20-30 years. The collodion process offered the photographer of the time the reproducibility of Talbot’s calotypes (without the legal encumbrances) along with the fine detail of the daguerreotype (at a lower cost of production).
Like the Daguerreotype the glass collodion positive required the protection of a matte cover glass and frame or case, but the quality of work was generally not as good. The difference in cost was however considerable, and even the poor could be tempted into a photographic studio for a cheap portrait. The process remained popular well into the 1880s.
Ferrotype / Tintype
A variation of the collodion positive process was carried out using black enamelled tinplate instead of glass. First described by the French photographer Adolphe Martin in 1853, the process became popular around 1860 under the name ferrotype or, particularly in the United States, tintype. It was much employed by travelling photographers who could prepare, expose and finish a positive picture on brown or black enamelled tinplate in a few minutes. Specially designed cameras were introduced in which all the chemical operations were carried out inside the camera. Although ferrotypes were rarely of good quality they were the cheapest form of photography in their day. With this process, beach and fairground photographers recorded many people who would not have gone near a photographic studio. The process remained in use until after the Second World War.
Albumen Printing
Whilst cheap and easy to produce, collodion positives suffered from some of the drawbacks of the Daguerreotype. Each was unique and required a protective case. The glass negative could be printed on the salted paper used for the Calotype process but in 1850 Louis Désiré Blanquart-Evrard published the description of an important improvement. By coating paper with albumen containing ammonium chloride before sensitizing with silver nitrate, a smooth, slightly lustrous surface was achieved. The new process improved the ability of the paper to record fine detail and the albumen paper print was rather less prone to fading than the Calotype. The albumen printing paper was ideal for the glass collodion negative and remained in almost universal use until the 1890s. The prepared paper was placed in close contact with the negative in a printing frame and exposed directly to strong daylight. When the desired density had been reached the print was removed from the frame in the darkroom, fixed in ‘hypo’ and, usually, toned - a chemical process using gold, giving the image a rich sepia or chocolate-brown colour and also helping to improve its permanence.
Although the printing process was simple enough, the extra work involved made the paper print more expensive at first than the collodion positive. In 1854 Andre Adolphe Disderi, a Parisian photographer, patented a method by which several portraits could be photographed on a single plate. One printing operation thus produced a number of prints, greatly reducing the cost. Disderi popularized a small mounted print size of approximately 2.5" x 4", which, from its size, became known as the carte de visite photograph. It became widely popular around 1860, and a craze soon developed for collecting carte photographs of celebrities, as well as those of friends and family. Photographers competed with each other to photograph the famous and infamous, supplying stock photos of royalty, artists, churchmen, writers, actors actresses and politicians. Some photographs ran into editions of thousands, especially pictures of the English Royal Family.
The portraits were taken either with multiple-lens cameras exposing four, six or more pictures simultaneously or with a single-lens camera taking photographs in succession on a plate moved between exposures. The prints were mounted on cards, often with elaborately printed backs. The poses, usually full-length in the early examples, are often stereotyped and wooden in appearance, varying only in the features of the sitters and in a limited range of backdrops and studio furniture. The carte de visite remained in general use until well into the twentieth century but after 1866 it began to give way in popularity to the ‘cabinet’ photograph, similar in presentation and appearance to the carte but much bigger, 4" x 5.5", and a more suitable size for quality portraiture.
The trend from case photographs towards paper prints created a demand for albums in which to keep them. The pages of the stiff board had apertures cut to hold cartes and, later, cabinet photographs. The album frequently had ornate covers; mother of pearl, plush, tooled leather, carved wood and Japanese lacquer were among the materials used. Some albums for display on mantelshelf or tables had built-in clocks; others had musical box movements which played as the pages were turned.
Progress
The wet collodion process and albumen printing paper revolutionized photography. By 1860 the Daguerreotype and Calotype processes were virtually obsolete. The wet-collodion negative plate was very sensitive and gave finely detailed pictures - but there was one big drawback. The need to expose the plate while still wet meant that the photographer had to carry his darkroom with him if working away from home. Portable darkrooms were sold, usually in the form of tent-like structures which collapsed into boxes the size of a large suitcase. When fully erected they were big enough for the photographer to get his upper body into, while daylight was excluded by a canvas light trap. As well as the dark tent the photographer had to carry the chemicals for coating, sensitizing, developing and fixing, a supply of cleaned glass plates, dishes and tanks and a container for water, which also had to be carried if none was to be found on the location. The photographer also needed to carry his camera, plateholders and tripod. From around 1860 the heavy and bulky sliding body camera typical of the Daguerreotype period rapidly gave way to the folding bellows type. By this ingenious design a camera, quite large when erected, could be made to collapse into a small, lightweight package. All this paraphernalia was necessary for a single photograph; it was cumbersome and expensive.
Whilst the wet collodion process gained huge popularity due to the quality of the image it produced, it had an obvious disadvantage in that the entire process, from coating to developing, had to be done before the plate dried. This gave the photographer no more than about 10 minutes to complete everything. It was hugely inconvenient for field use as it required a portable darkroom and the plate dripped silver nitrate solution caused stains and potentially explosive build-up of nitrate residue in the camera and plate holders. Collodion-based photography was also only sensitive to blue light; all darkroom work could be done under red or dark-amber lighting. However, in collodion images warm colors appeared dark, and cool colours were difficult to separate tonally. As a result, it was almost impossible to render clouds in the skies.
Despite these disadvantages, the wet collodion process proved extremely popular, offering high image quality and replication capability for a relatively low cost to landscape, architectural, portrait, and art photographers. The generous nature of Frederick Scott Archer, described in the British Journal as “a man of very obliging disposition”, ensured the wide and unencumbered dissemination of the details and techniques for the process, lowering the technical hurdles for interested parties. This generosity, unfortunately, did not serve Archer well and he died almost penniless in 1857 - just six years after introducing the collodion process to the world. Today almost unknown for his contribution to the art of photography, Archer’s wet collodion process served as the world standard until it too was replaced in the 1880s by superior, more convenient technologies.
If a reliable method could be found to prepare plates in advance, with no loss of speed or quality, a great saving in cost and weight could be made. The whole operation would also be much simpler. The photographer would need only a camera, a tripod and a few dry plates. The search for an improved dry process went on.