Re: argentotype again

[Alberto Novo <alt.list@albertonovo.it>]

Marek,
I regret for this late reply. I was without a PC from Thursday. 
> 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".
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) 
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 Strand’s 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. 
> 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.
"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.
POTA= potassium oxalate or phenidone+sodium sulphite? I suppose you are 
referring to the first (as in Willis' patent). 
> I 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.
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.html 
Alberto