[alt-photo] Re: metallic/chromo/gold/halochrome/Seigel/Dalla Tana

[Alberto Novo]

Christina,
thanks for sharing your research.
Only a few remarks: 

>I am most positive Dalla Tana is doing it on a developed and fixed/previously made print as you can see, below, in the Halochrome section.

Dalla Tana writes (both in the Italian and English texts) that he develops 
by brush for 10-15' (Why by brush? Perhaps because he don't want to use too 
much developer? Because he wants that the developer is completely exhausted 
at the end? Because he don't want to smudge the back of the paper?...), then 
he plate (or tone) before stopping and fixing. 

> "Redeveloper Formula:
> Halo-Chrome® Silver Toner (1)
> AMMONIUM HYDROXIDE (SARA III) Percent: 30
> SODIUM HYDROXIDE (SARA III) Percent: 2.5
> NON-HAZARDOUS INGREDIENTS AND WATER Percent: 67.5 
> 
> POST FACTORY  © JUDY SEIGEL
> STEP TWO:  REDEVELOPER FORMULAE STOCK SOLUTIONS (mix 1 +10 at time of use)
> 2 g. hydrazine sulfate
> 1g hydroxylamine hydrochloride
> 50ml 25% ammonia
> 120ml 10% sodium hydroxide
> 40-200ml distilled water.
> (and LOTS of other formulae).

Without a reducing substance (hydrazine and hydroxylamine in P.F. formula) 
there will be no plating out. So, among the "non-hazardous ingredients and 
water" there has to be the reducer. Because hydrazine and hydroxylamine are 
hazardous, I could think to something like ascorbate, tartrate, an aldehyde 
or glucose.
The formula for silver plating a glass is very similar:
1) solution of silver nitrate and ammonia
2) solution of silver nitrate and Rochelle salt
Mix the solutions and pour over the glass. Wait about 30' @ 30-40°C
or (from the Tollen's test for aldehydes):
1) solution of silver nitrate, sodium hydroxide and ammonia
2) solution of glucose or sucrose+acid (this last can be used only some days 
after the preparation)
mix, etc. Plating is immediate.
WARNING!!! throw the mixed solution and rinse the vessel ASAP because the 
silver + ammonia solution with time forms silver azide, which detones simply 
by rubbing also if it is wet. 


Alberto
www.grupponamias.com
www.alternativephotography.com/articles/art102.html