Before the Civil War, practically all photographs made in the United States were either daguerreotypes or the imitations of them known as ambrotypes and tintypes. Superficially they all look alike, but in reality they are quite different. The daguerreotype was made with a silvered copper plate, the ambrotype with a glass plate, and the tintype on thin sheets of iron japanned black.
A daguerreotype can instantly be recognized if the picture looks like an image on a mirror. Indeed, the process invented by Jacques Louis Mande Daguerre in 1839 was called "a mirror with a memory." The silver plate was polished until it was mirror bright, made light-sensitive by treating it with iodine vapor, and exposed in the camera for about twenty seconds. It was developed with hot mercury, fixed in hyposulphite of soda, rinsed in water, and dried. The quicksilver adhered to the coated plate in proportion to the light received, forming a whitish amalgam.
The plate was so fragile that the slightest touch would utterly destroy the image, and it was therefore very carefully mounted. Daguerreotypes do not fade on exposure to light, and are sensitive only to excessive heat, which drives off the quicksilver forming the image. If daguerreotypes seem faded and dull, it may be that they are hidden behind cover glasses on the under side of which the condensation of years of moisture has left a cloudy deposit.
In 1851, the year Daguerre died, a new photographic technique was introduced in England by Frederick Scott Archer. Instead of using a silvered plate, he used a glass one, which he first coated with a mixture of collodion and potassium iodide. Before this sticky emulsion was thoroughly dry, he plunged the plate into silver nitrate solution, forming light-sensitive silver salts. The plate was then exposed and developed while wet.
The result was a negative, but when viewed against a black background, the glass plate appeared as a positive. Ambrotypes, as these positives were called, were sometimes placed against black velvet, dark paper, or a piece of tin or glass painted black. Sometimes the back of the plate itself was painted black. At times, ruby instead of transparent glass might be used, which made further treatment unnecessary.
Ambrotypes were not only easier to make than daguerreotypes, but the materials were less expensive, the exposure shorter, and the picture easier to see. Like daguerreotypes (and unlike paper photographs), these pictures on glass could be processed while the customer waited.
Daguerreotypists denounced the ambrotype as "the black art of asphaltum," from the varnish used to back the plate. J. H. Fitzgibbon of St. Louis wrote that "the star of Daguerre is obscured by a black cloud called ambrotype; but the black, nasty, filthy, ghastly, dead, inanimate, flat, shade of shadows are beginning to bust, break, peel, turn, change all colors, and must in time die out without any other exertion than their own selves."
Die they did, but not by their own exertion. They were replaced by paper photographs and tintypes. Customers who sought quality, particularly if they felt the need of the retoucher's skill, ordered paper photographs. Others went to the tintype man.
The process of making melainotypes, or ferrotypes, as tintypes were also called, was developed in 1858. The collodion was poured on thin blackened sheets of iron instead of glass plates. The name "tintype" is misleading, since as one ferrotypist wrote, "not a particle of tin is used in making or preparing the plates."
At first tintypes were mounted like ambrotypes, and they then look so much alike that it is impossible to tell them apart without removing the cases. By the time of the Civil War, tintypes were no longer protected by glass but were enclosed in paper mats. The greatest advantage of the tintype was its durability: it needed no protection and could be sent through the mails in an ordinary letter - a boon to soldiers away from home. Tintypes could also be cut down to fit into round or oval lockets and watch cases.
The ferrotypists soon devised a method whereby they could take twelve identical pictures at the same time, on a plate with twelve lenses, or "tubes." These little pictures, in "gem" size, an inch square, were cut apart and framed without glass, or mounted on cards or in tiny albums with slotted openings.
Tintypes were referred to as "pictures for the millions." At fifty cents a dozen almost anyone could supply portraits to all his relatives and friends. Long after the daguerreotype and the ambrotype had become obsolete, the public continued to rely on the tintype men for informal and inexpensive portraits. It was not until 1890 that snapshots replaced tintypes in the family albums.