Re: Oxalic Acid + Potassium Chlorate


Eric Neilsen (ejnasn@laplaza.org)
Fri, 29 Jan 1999 08:55:13 -0600


dkern@juno.com wrote:
>
> I'm making my first #1 and #2 solutions for pt/pd and have three SHORT
> questions.
>
> 1) Is oxalic acid useful/necessary? I understand it may promote longevity
> of the solution and increase contrast.
>
Yes, it will incease the life of your ferric oxalate.
 
> 2) Can potassium chlorate be kept in a separate solution from the #2 and
> added when sensitizing the pt/pd?It was mentioned in a thread a week or
> so ago but it was not clear what concentration solution to use.
>
Yes, you can keep it seperate. What concentration will depend on how
you make your prints. There seemed to be some dicussion of that in the
pipette/drop thread. A less concentrated solution would allow greater
control of concentration in the coating solution. Remember that
platinum and palladium require different amounts to affect contrast
change.
 
> 3) What are some other contrasting agents and methods of application?
> Does sodium dichromate work in an ammonium citrate developer the same as
> in potassium oxalate? Does it cause less grain than potassium chlorate?
>
3% Hydrogen Peroxide works both in the coating solution or developer. If
it is used in the developer, you will need to work out a replenishment
system. (Big pain). the dichromates generally cause very little or no
grain when used to increase contrast. I have only used them with pot ox
developers. Warm/hot developer will also lower contrast.

Hope this helps some.
 
> Thanks!
>
> David Kern
>

-- 
Eric J. Neilsen
7910 Treehouse Ln, Apt 1095
Dallas, TX 75231
214-378-8383
http://laplaza.org/~ejnasn



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