Anyone who has examined a slightly underexposed negative may have noticed an odd phenomenon. If you hold it in the light with dark material behind it, the negative may look like a positive.
That is the principle behind the ambrotype, a photograph on a plate of glass, popular in the 1850s and 1860s. It is really a negative with the emulsion on glass instead of our modern film; it's backed with black shellack, paint or other material so that it appears to be a positive.
The name comes from the Greek "ambrotos" for immortal, and type. "Type" was applied to all sorts of photographs, from the earliest daguerreotype introduced in 1839 to the tintype that was in vogue through the early years of the 20th century.
The ambrotype was briefly popular between the times of the other two.
A daguerreotype (named for the inventor, Louis J. M. Daguerre) was made on a copper plate covered with a layer of polished silver. Its surface was so delicate it had to be protected behind glass and kept safe in a small leather case.
The daguerreotype, ambrotype and tintype were all one-of-a-kind photographs. If you wanted another print, a photographer would make a copy daguerreotype. Also like daguerreotypes, ambrotypes are so delicate they had to be protected in cases.
But unlike daguerreotypes, with their copper and silver, ambrotypes were relatively inexpensive. They could be made of glass and chemicals, plus the case.
Because of cost, as soon as they were introduced in the middle 1850s, ambrotypes began destroying the daguerreotype market. Ambrotypes became wildly popular by 1857.
But they did not last long. When the Civil War began in 1861, thousands of soldiers on both sides rushed to have their ambrotypes taken for their families. Photographers followed the armies in the fields and soldiers lined up to have images taken.
But all too often, mules carrying the army mail would stumble, or some other accident would jar the ambrotype — and the family back home would get a case full of glass shards. So a similar kind of photograph rapidly gained in popularity.
This was the tintype, a positive made the same way as an ambrotype except that it was taken on a piece of metal, not glass. Contrary to its name, a tintype actually is made on a thin, dark piece of iron, not tin.
The tintype was so tough that it didn't even need a case. It could be sent through the mail, suffering nothing worse than a bend or a rumple. Ambrotypes quickly faded from popularity. By the end of the Civil War in 1865, the art was nearly dead.
E-MAIL: bau@desnews.com