Those of us interested in studying and interpreting the mid-19th century have a distinct advantage over those who focus on earlier eras: the advent of photography.
It cannot be overstated what a vast amount of information photos from the past have to share with us, but as with any resource, we need to be cautious in our assumptions.
A couple of vastly different interpretations could be made of the above image, is it an abolitionist lady making a statement? Or a southern matron illustrating a very different viewpoint?
Actually neither is correct:
Period photography can play some unintentional tricks (although the concept of "retouching" photos existed, even then), especially in regards to how certain colors photograph. Note the appearance of the bright yellow trim in the tintype - it looks black. Virginia Mescher has posted a very good article regarding the phenomenon here.
Note too the complexion differences, one lady having a naturally ruddy tone, the other more olive and photographing dramatically differently too!
I was very impressed with the work of the tintypists, Whalen and Shimmin - they spent a great deal of time on proper poses and lighting and the results were impressive. They also experiment with some modern style use of the medium, which were equally impressive.