I came across this article by Rudolfo Namias about using a combination of ferric chloride with oxalic acid as the sensitizer and silver nitrate as the developer. It says in the article that, ferric chloride is reduced to ferrous chloride on exposure, which then reacts with the oxalic to form ferrous oxalate in situ in the paper. Using silver nitrate as a developer, one gets image-forming deposition of Ag metal on being reduced by the oxalate. https://books.google.com/books?id=AydJAQAAMAAJ&pg=PA274&lpg=PA274&dq=a+home-made+printing+paper+rudolfo+namias&source=bl&ots=2AX-0s4-4n&sig=IKKOD8PIfwb0pUnfcEXAWLoxpW4&hl=en&sa=X&ved=0ahUKEwiIjOuB2q7TAhUH0YMKHfjmAGYQ6AEIJDAA#v=onepage&q=a home-made printing paper rudolfo namias&f=false My question is this: Is this not the same as or similar to the classic Kallitype process using Ferric Oxalate / silver nitrate as the starting materials? If so, why would this method be not attractive, given that you do not need to have relatively expensive ferric oxalate around? There are I am sure some other issues. Wonder if anyone has tried this method. Just curious.... Addendum: In order for this process to be purely Kallitype-like, silver nitrate would have to be incorporated in the sensitizer. Developing with silver nitrate would be a little more clumsy not to mention wasteful of silver, countering any cost benefits alluded above.