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

[Alberto Novo]

Christina, 

> He is what I term "selectively developing" by brush then--which would then keep parts of the print undeveloped/white.  I teach that in my class--students expose a print normally and develop normally but instead of immersion in the tray of developer they brush it on selective places to bring out the image, bit by bit, leaving the undeveloped parts white.

Please read carefully his text. He writes "utilizziamo la formula base, 
pennellando gentilmente la stampa dai 10 ai 15 minuti. Poi alziamo il piano 
per 5 minuti e lasciamo drenare la stampa (we use base formula, gently 
painting gold in the develop from 10 to 15 minutes. Then we lift the board 
and let the print drain)". BTW: "painting gold" is not in the Italian text 
which is simply "gently brushing the print for 10 to 15 minutes". But my 
point is an other: if we selectively developed the print and then "let the 
print to drain", we will likely have streaks. So I am not sure he is 
selectively developing. 

> OK, so for the second point--you are saying that Judy's formula is correct to plate out because it contains a reducer, but Halochrome must have something inert added in the 67.5% to allow this to happen (ascorbate, tartrate, aldehyde, glucose).  The Redeveloper part of the Halochrome is "Proprietary" so they don't list it, and don't have to I suppose, because it is inert.  Sneaky sneaky.  I will mix up a mock Halochrome and test sometime this summer.  I have tartaric acid and citric acid, would those be OK?

OK for tartaric.
Halochrome does not writes that in the 67.5% there are inert compounds. They 
write "non toxic": like tartrate and glucose, in fact. 

> Now I have a question for you:
> In my chromo formula, why does Tektol work better than Dektol?

My guess is that the silver that is not in the plating solution is dissolved 
by the plating solution (which contains ammonia) from the smaller grains of 
the image. Then it is plated on the bigger grains. As Tektol is a cold tone 
developer, it should give rise to silver grains bigger than those coming 
from a hydroquinone developer.
What happens if you add a single drop of a silver nitrate solution in your 
plating solution? You could start with a 10% solution diluted 1:10, but 
remember to throw the plating solution after the use. I bet the plating 
action will be much faster. 

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