Dating an ambrotype
The “common ambrotype” is a clear glass support backed with a dark piece of textile, metal, secondary glass or paper, or painted directly onto the back of the image.
The “ruby ambrotype” is printed onto a dark glass support that is red when viewed in transmitted light.
Either fault leads to the same result: fading image, discoloration, etc. Popularity: The tintype was very popular during the Civil War because every soldier wanted to send a picture of himself with his rifle and sword home.
Many times, the silver image tarnishes with silver sulfide in the same way as silverware. Step two was to make a contact [print] with a second sheet of sensitized paper to make a positive print. As the public sought lower prices, the cases (which cost more than the finished photographs) were eliminated.
The cost: .00 (more than a weeks pay for most people). Calotypes were never widely popular, and most of those surviving are in museums. In their place, paper folders of the size of the then popular card photographs were used for protection.
The calotype made only minor inroads in its popularity, even though the calotype negative permitted duplication, while the Daguerreotype had to be rephotographed or etched and inkprinted.
The wet collodion and tintype processes finally superseded the Daguerreotype, but it left a rich legacy of some of the earliest historical photographic images.
Unlike paper photographs, however, these three types did not fade.