The dryplate tins I have used in the past are the ROCKLAND products. Oyhrewise I use collodion for tins. But what Im looking for is a formula used for developing the dry gelatin tins like that of Rockland. They have an MSDS display on thier site for their products and it does show the composition of the tintype developer. It is basicaly dectol with Ammonium Thiocyonate.
I tried to make my own but it had a tendancy to turn black in short order and the results were not that good, maybe the emulsion or something was bad.
Other dryplate techniques I used with great success are the dry collodion plates for negatives wich are slower than wetplate but still give good negatives.