Re: argentotype again
I regret for this late reply. I was without a PC from Thursday.
The date are a little confusing: US patent is 1914 (application date September 22th, 1913), while the UK one is called 1913 (appl. date September 4th, 1913; accepted Sept. 3rd, 1914)I you read Willis original patent, which I can't remember if it is dated 1913 or not, the process that he describes as satista (and I am not sure if he uses that name or not) is not what we call "satista now".
Willis does not describe his process as "satista", but I have found a general agreement on this name. See for example:
Barro L. "The Deterioration of Paul Strandís Silver-Platinum Prints", Abstracts from the Photographic Materials Group of the A.I.C. Annual Meeting, San Juan, Puerto Rico 2003 (http://aic.stanford.edu/sg/pmg/images/abstractswintermeeting.pdf), AND the references therein.
"The paper first of all receives a coating of chloride of silver which may be applied or attached to the surface as an emulsion in gelatine or other suitable medium or formed on the surface as an emulsion in gelatine or other suitable medium or formed on the surface by the well known process of double decomposition" (page 2, row 22-25 in the 1913 UK patent 20,022; page 1, row 105-110 in the US patent 1,120,580). So not only a silver chloride gelatine paper, but also a well washed sensitized salted paper.His process involves sensitising silver halide emulsion with platinum, exposure with UV and development in POTA developer. I tried sensitising silver chloride paper (Forte wt) with Pt salts and it workes OK. I need to reread the patent again as it has been a few years.
POTA= potassium oxalate or phenidone+sodium sulphite? I suppose you are referring to the first (as in Willis' patent).
Your recipe (development in 4% silver nitrate) is what Dick Sullivan suggested I believe in 2000 (see a date in his article), calling it "satista+": http://www.bostick-sullivan.com/articles/satista.htmlI never followed his recipe as described in the patent, but I would think it would work OK as my crude attemt to sensitize commercial paper gave decent results.