[alt-photo] Re: Zia standard solutions

[Terry King]

Loris


There is a definitive answer. Use percentage solutions.


When the manuals confuse by not using the right terms, I agree that all one can do is test for yourself.


Incidentally, all this stuff about 'stochiometric balance' and 'molecular equivalence' in discussions at this level is inappropriate. It really is the worst kind of 'pointy hat 'stuff.  This kind of jargon does not impress.  It reminds me of the prospective platinum printer who told me that he had decided, after reading a well known manual on the subject, that he had decided not to take up platinum printing as he did not understand the maths!  Of course all the maths in the manual were quite unnecessary in the making of good platinum prints.


Terry 












-----Original Message-----
From: Loris Medici <mail at loris.medici.name>
To: The alternative photographic processes mailing list <alt-photo-process-list at lists.altphotolist.org>
Sent: Tue, 20 Jul 2010 17:11
Subject: [alt-photo] Re: Zia standard solutions


I don't think there's a definitive answer to that. For instance, I remember Sam 
Wang suggesting dilution of argyrotype soln. 1+1 with water (for some specific 
reason which I can't remember right now) and someone tried it (was it Paul 
Viapiano?) and got better results, "for his set of parameters". I guess one has 
to test and see if dilution (w/o affecting stoichiometric balance!!! That is, 
w/o affecting the molar equivalence between the compounds involved) works for 
them.

Regards,
Loris.

On 20.Tem.2010, at 18:55, Christina Anderson wrote:

> Jalo and others,
> (Oh my, I'm approaching my ten-post limit for the day)
> Jalo's point brought up a topic I have been meaning to ask.  If Jalo just uses 
the 25ml and adds the chemicals, he essentially has just diluted the solution by 
a very teeny amount.  Years ago I read about diluting the combined pt/pd 
solution 50% with water and double coating. This was to get around the very 
absorbent Rives BFK situation.
> 
> My question is this:  has anyone diluted the more expensive precious metal 
solutions with water as a general practice, either to save $$, or to deal with 
absorbent papers, or whatnot? I know that if the ratio of ferric to pt/pd goes 
awry, you get a weak print (seen that in workshops), but given the ratios 
staying the same, maybe even a 10% or 20% addition of water to the total mix 
might be possible as general practice? Just wondering if anyone does this, and 
if so, at what point does it not work.  The person in question was double 
coating so it wasn't going to affect the total amount of pt/pd on the paper, so 
I am asking about lessening that total amount.
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