Good points both, but we were talking about needing explanations of *how* the photos were taken (mobile lab on the beach, gaining the trust of a reclusive community, etc) rather than explanation of what we're seeing in the images.
To pursue the natural history analogy, understanding my image of a drab bird on a stick would be enhanced if one could tell that the state of its plumage indicated that the photo was taken during the mating season, and that the bird's posture was defensive. One could read a lot into that, and that seems analogous to the vocabulary of symbols which we have lost. But it's a completely different type of explanation than the one about it bring a rare bird living in a leech-infested swamp.
In the case of the tintype, the medium is the message. Its use imposes a certain method of working/posing/collaborating, which in turn produces results that you simply wouldn't get from a faster, more convenient medium, which changes the way such a portrait is perceived. There's the contradiction of documenting a typically laid back culture with a medium that's associated with stiff formality. The contrast between a modern lifestyle seen through an old process. Everything about the process adds to the result in this instance. It's like showing your working for a Math problem - the answer is important, yes, but you get more marks by showing how you manipulated those numbers and formulas to get to a result.
Now as for the theoretical drab bird on a stick, I assume that it's perfectly exposed, perfectly in focus, and technically acceptable. Very safe and 'proper'. The process and the story behind that image would be glossed over by that clinical perfection - of course, being clinical can be used to great effect, but more often than not it comes across as plastic.
A more interesting way of visually conveying that bird's rarity and the struggle to get to that result could be to present that single bird on a stick frame within sequence of frames just showing the stick. Or place that drab bird in the middle of a grid of photos, with the other photos showing the physical process of getting to the swamp, setting up, and waiting. Or even a GIF where the bird is present in a single frame. That way the medium conveys how fleeting seeing (let alone capturing it in an image) one of those birds actually is.
Now most of the time the way you took a photo isn't as important as the way you present it, but I think tintype is a special case in the way it rolls everything together. It's self referential, the result always points back to its process, a bit like looking at the rings of a tree drunk or layers of sediment in a rock. Polaroids have a hint of that too. Regular film (and digital), not so much.
In a commercial sense it is highly unlikely their parents would ever want that on their wall, and perhaps moreso their grandparents
