"I am somewhat familiar with the wet plate processes (from reading) and
this is TOTALLY different"
----No kidding! It sounds like this is a sort of pseudo-tintype, possibly based on a graphic-arts type of developer. There are some chemistries that are (or were) used to create printing plates and which involve a solubilizing developer; maybe Rockland is borrowing from one of those technologies. It seems odd that the image doesn't change with fixing; I understood that the Ag-Plus product was just a high-silver gelatine emulsion, otherwise fairly conventional. If your finished tintype depends on a silver halide image for visibility, I wouldn't recommend offering any guarantee of longevity...
The odd thing is that in order to get continuous tones, you have to create transparency in proportion to exposure. The usual way to do this (as in collotypes) is to expose through the base, hardening the coating so that the part nearest the base is firm enough to hold everything together. Working from the "top" as it were, it seems that one of two situations would have to exist: the exposure and development would be closely and delicately tied to the emulsion thickness (in order to be able to display mid-tones) or there would have to be a proportional bleaching process wherein the actual gelatine stayed in place, but proportionally lost opacity.
I think that in light of your description, most of the available photographic insight (starting with mine!) is going to turn out to be irrelevant.
If someone with a better understanding of the technology doesn't chime in, perhaps you should contact Rockland and offer them the URL of the start of this thread. If it were _my_ product and this many people were interested in it, I would certainly want to get the issue straightened out in a hurry!
You could also try, if you haven't already, the alternative processes forum over on photo.net. Some folks who at least _sound_ authoritative contribute over there on occasion.
Good luck!
Bookmarks