From: Christina Z. Anderson (zphoto@montana.net)
Date: 09/21/02-08:17:38 AM Z
> Christina Anderson wrote:
> > Are potassium citrate and sodium citrate interchangeable?
> > Are ammonium, potassium, and sodium thiocyanate interchangeable?
>
> Tom Crowe wrote:
> > ... most potassium and sodium compounds with the same anion (citrate,
> > etc) would be interchangeable, but you must adjust the formula for the
> > proportionate difference in the molecular weights of the compounds.
>> Jeffrey D. Mathias wrote:
> Aside from adjusting the formula, you should expect differing results in
> the print. At least with Pt/Pd, changing or mixing various cations can
> give a wide variety of results in the print. This does not necessarily
> have to be restricted to the coating mixture (could be in developer).
> Adjusting/ balancing the formulae is critical for consistency and
> predictable results. Information on balancing (for Pt/Pd) is presented
> in my on-line guide at link below.
Thanks both of you. This is just what I need to know. I"m working with dye
mordanting and bleach etch formulae here, so the changes in the final print
are not an issue, as that wouldn't bother me. But in dye mordanting, if I
am using something wrong in the formula, then I may end up making the whole
print subject to stain, and that would be more critical. I am comparing
different formulae in action, and one may call for ammonium thiocyanate, one
for sodium, and I'm trying to get by with having to purchase as little as
possible to do my testing. When you compare, let's say, 10 out of print
books that include these processes, not a one matches in amounts or
chemicals used in their formulae, and it's not like you can know which one
works best, without buying all the chems. So I suppose I may just try the
shot in the dark approach, and pick one.
BTW, Bergger paper is a beautiful paper to work with, and mordancages
quite well. I'm using the VCNB (neutral glossy). And the Vesta paper that
is available online thru Econozone, which is half the price of other papers
(like $25 a box of 50 11x14 coldtones) is a good one to experiment with,
too, altho not as thick and spongy and beautiful as Forte or Bergger.
Chris
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