Then the perfection of new techniques brought prices even lower and quantities even higher. The collodion process, invented by Frederick Scott Archer in England in 1851, almost at once replaced the calotype. Three times, in three guises, it threatened the daguerreotype, and finally triumphed.
Like the calotype, the process was primarily a method of making negatives. Collodion, discovered in 1847 as a means of protecting wounds, is a mixture of guncotton in alcohol and ether; flowed on a surface it dries to form a tough, skin-like film. Archer first used it to save glass plates. The imperfection of the talbotype because of its lack of transparency had early suggested the replacement of paper as a negative support by glass. To attach the silver salts to glass various substances had been tried, even the gluey slime exuded by snails, until partial success came with the use of egg white. These albumen plates — invented by Niepce de Saint-Victor in 1847 — gave excellent negatives, of a brilliance and fineness of detail far surpassing the talbotype. Their drawback was a loss of sensitivity so great that they were practical only for landscape work. And to photographers used to light-weight sheets of inexpensive paper, glass plates were heavy and dear. Archer described in The Chemist for March, 1851, his original and highly ingenious technique. Glass was coated with collodion in which potassium iodide was dissolved. It was then dipped in silver nitrate, and exposed while wet. After development in pyrogallic acid, the film of collodion bearing the negative image was stripped from the plate, rolled up with paper around a glass rod, and carried home to be fixed and washed. “Thus one piece of glass,” he wrote, “will be sufficient to make any number of drawings upon, the above operations being repeated for each picture.”
As finally perfected, a separate piece of glass was used for each negative. The seven following steps were carried out:
1. A piece of glass was placed in a vise and thoroughly cleaned and polished.
2. Holding the cleaned glass by one corner, enough of the viscous collodion (to which an iodide and often a bromide had been added) was skilfully flowed over the surface to form a smooth, even coating.
3. In the subdued orange light of the darkroom the coated plate, while still tacky, was excited, or made light sensitive, by soaking it for about five minutes in a bath of silver nitrate. When it had become creamy-yellow it was taken out, drained and put, still wet, into a light-tight plate holder, or shield.
4. “Place the cap on the lens [the beginner was directed by John Towler in his handbook, The Silver Sunbeam']; let the eye of the sitter be directed to a given point; withdraw the ground-glass slide; insert the plate-holder; raise or remove its slide; attention! One, two, three, four, five, six! (slowly and deliberately pronounced in as many seconds, either aloud or in spirit). Cover the lens. Down with the slide gently but with firmness. Withdraw the plateholder and yourself into the darkroom, and shut the door.”
5. The plate was removed from its holder and over its surface a solution of pyrogallic acid or ferrous sulphate was poured. In a few seconds the image began to appear, increasing rapidly in brilliance. When it was judged to be fully developed, the plate was rinsed in clean water.
6. Hypo or potassium cyanide in solution was now poured over the developed plate to dissolve the remaining unaltered silver salts. The plate was then well washed under running water.
7. Over a gentle flame the fixed plate, held between thumb and forefinger, was rapidly moved until dry; while still warm it was varnished.
The process required experience and skill of hand; a mistake in any one operation spelled failure. The photographer was chained to his darkroom, for all these operations had to be done rapidly, before the collodion dried or else excess silver nitrate would crystallize out and spoil the image. Because the plate had to be kept continually moist the process came to be called “wet plate.”
Wood engravings from contemporary manuals showing steps of the wet-plate process
Label from a mass-produced daguerreotype. Collection Walter Scott Shinn, New York
Although invented for making negatives. Archer described the application of his technique to the production of positives. A wet-plate negative could be viewed as a positive simply by placing it against a piece of dark material or by painting the back black. The highlights were represented by the grayish-white tone of the developed collodion emulsion; the shadows, being more or less transparent, revealed the black background. Like the daguerreotype, each such picture was unique; the very glass plate exposed in the camera was itself the final product. Thus Archer's modification lacked the power of duplication, but it had the advantage of speed; the sitter could take the finished picture with him almost immediately.
These glass positives, because of their similarity to the daguerreotype, both in appearance and in manner of production, were especially popular in America. Scott Archer’s invention, which he had published without restrictions of any kind, was patented by James Ambrose Cutting of Boston in 1854. Marcus A. Root, a Philadelphian writing master turned daguerreotypist, named the pictures ambrotypes. Like the daguerreotypes, which they imitated, they were commonly enclosed in leather or composition cases.
The familiar tintype is a modification, the support for the light-sensitive collodion emulsion being, instead of glass, thin metal plates japanned black or chocolate color. The manufacture of such plates was begun in 1856 by Peter Neff, Jr., who named the process melainotype, and by Victor M. Griswold, who chose the name ferrotype. The more popular word tintype was introduced later.
Because the surface of the tintype was not fragile they could be sent through the mail, carried in the pocket, and mounted in albums. They were processed while the customer waited. They were cheap, not only because the materials were cheap, but also because, using a multi-lens camera, several images could
| Handbill of Alexander Hesler, who opened a Chicago gallery in 1855. Boyer Museum. Chicago, Ill. |  |
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| Niagara Falls. Ambrotype, about 1856. Collection Zelda P. Mackay, San Francisco, Calif. |
be secured with one operation. After processing, the plate was cut into single pictures with tin snips.
Tintyping was usually casual; when the results have charm it is due to the lack of sophistication and to the naive directness characteristic of folk art. Records of outings, mementos of friendships, stiffly posed portraits of country folk against painted backgrounds are common: views are few. The process lingered in the backwaters of photography as the direct yet weak descendant of the daguerreotype.
Despite the competition of direct imitation, neither the tintype nor the ambrotype dealt the death blow to the daguerreotype. That was left to a third application of the collodion technique, the carte-de-visite photograph, patented in France by Adolphe-Eugene Disderi in 1854. The name refers to its similarity to a common visiting card in size, for it was a paper print pasted