This past weekend I attended a genealogy conference where I became involved in a conversation surrounding Daguerrotype and Ambrotype photography. The question came up: how do you tell the difference between the two?
The ambrotype you see above is probably the oldest photograph in my collection. The ambrotype was first used in 1851 and was patented by James Ambrose Cutting in 1854. Eventually, it became the photograph of choice, overtaking the earlier Daguerrotype in popularity mostly because it was less expensive. The Ambrotype is actually a negative image on glass made positive with a black backing. Most often it is cased, as you see above. Ambrotype use died out around 1880, though never as popular as it was in the mid-1850s, due to the invention of tintypes and "cartes de visite."
You can differentiate an ambrotype from a daguerreotype by its reflectiveness. The ambrotype will not have a mirror-like image when you look at it from different angles. If you take it out of the case and hold it up to the light, you will be able to see through the ambrotype. I know this particular artifact is an ambrotype because the image is on glass, and not on polished silver as a daguerreotype would be. Ambrotypes were made from 1851-1880, but this one probably dates somewhere in the mid to late 1850s.
Assuming it is original, I am guessing that the case is probably an early one. In the back half of the 1850s the mat and brass preserver became highly ornate. As you can see, ours is quite plain. It probably dates to 1855 or earlier. The young girl's outfit could provide clues as well. The wide, shallow shoulders of her dress point to the 1850s. I'm not a costume expert but I do wish I could see what type of legging were worn, as that, too, could help with dating the image. This is probably the only likeness in existence of this particular sitting. Ambrotypes, for the most part, were one-offs.
I found this ambro at an antique show and sale in Red Deer, Alberta about 25 years ago. The problem with ambrotypes is that they are so often unidentified. This one is no exception. It is highly unlikely that I will ever learn the background story of this young girl.