I'm going to disagree with the assessment of the mother and child as a Daguerreotype, based on the very ornate mat around it, it lacks a certain depth to it, and the fact that it is relatively easy to read. If it is a Daguerreotype, it would be very hard to see the image looking at it straight on without some kind of black non-reflective material in front to prevent reflected light. While Daguerreotypes do tarnish, especially around the edges where the mats come into contact with them, tintypes and ambrotypes are not immune to tarnish rings either, and I have seen wet plate collodion images with similar tarnish before.
While Daguerreotypes were made into the 1860s, their heyday was 1839-1850, with significant decline by the mid 1850s as tintypes and ambrotypes and albumen prints took over. The short explanation of the differences:
- a tintype is on a piece of blackened steel (called "tin" because it was very inexpensive).
- an ambrotype is on a piece of glass - it could be clear glass, black glass, ruby glass or even milk glass. Ambrotypes are backed with something opaque to make them readable as a positive.
- a Daguerreotype is on a piece of silver-plated copper polished to a mirror finish.
All three of your images are in cases. This doesn't rule any image in or out as one medium or the other - dags, ambros and tins were all cased. You can get an idea of the date of an image based on the style of mat around it. The three mats you show are all examples of later style mats with multiple layers and ornate designs.
This is typical of an early (1840s) Daguerreotype:
Another example of an earlier Daguerreotype:
A cased tintype from 1861-62:
(this one I can date very precisely because A: the subject is my ancestor, and B: I had a civil war historian identify his unit based on the uniform, and he was very confident that it was early in the war from certain stylistic clues).
Here is a later Daguerreotype of a young girl - notice how the mat is fancier, but not as ornate as the tintype of my ancestor:
A milk-glass ambrotype:
I hope these examples are illustrative of the differences between the image types (Daguerreotypes have a certain depth to them that no other image type has).
There were two ways to make a wet collodion image on glass - if you shot it on clear glass, exposed it and processed it one way, you end up with a negative good for printing. If you expose and process it differently, you end up with a positive image that is unique. Tintypes are also wet collodion process images, but they are made on the aforementioned steel sheets that have been blackened with asphalt (or Japanned in the colloquial). One way to determine if an image you have is a tintype or an ambrotype (which can be difficult to tell apart when under a protective glass cover in a case) is have a small magnet. The magnet will be attracted to a tintype.
