From: Keith Schreiber (jkschreiber@earthlink.net)
Date: 12/14/02-04:18:58 PM Z
Hi Mateo,
Are the crystals green and needle-like? I posed a similar question back in
Feb '96 to which Mike Ware replied:
"This is, very probably, potassium tris-oxalatochromate(III):
K3Cr(C2O4)3.3H2O"
The archived message can be found at:
/lists/alt-photo-process/1996/alt96a/0457.html
Another chemist and alt-process person who I know personally (and who is
usually rudely dissed on this list) agreed that it is most likely a chrome
compound.
As far as effect on effectiveness, I can only speak from my own experience.
I keep 3 liter bottles of 7 "grades" as outlined by Arentz and replenish as
necessary. To be sure of the performance, I periodically print and plot a
set of 21-step tests of the full range of Potassium Oxalate + Sodium
Dichromate. I have not found the formation of these crystals to have any
significant effect on contrast or printing speed. Once, however, in over 10
years of Pt/Pd printing, 1 bottle (my #3 I think) did die for no apparent
reason.
Hope this helps,
Keith
J Keith Schreiber
www.jkschreiber.com
jkschreiber@earthlink.net
Mateo wrote:
> I was printing some stuff and had to break out my jug of potassium
> oxalate #5. When I picked up the container it sounded like a giant
> maraca. I heated up the juice to about 140s but the crystals would
> not go away. I filtered them out and used it anyway as I already had
> the exposure going. The print looked OK, but I only had time to do
> the one so I have nothing to judge it against. Would it be the PO or
> the Dichro that formed the crystals? If it's the Dichro, I would
> assume that I'm not getting the full contrast effect, if it's the PO,
> would it even matter? Has anyone had this same experience? I know the
> short answer is to mix up fresh stuff to be sure, just curious. (And
> I rate mixing things right up with processing film, it sucks.)
>
> mateo
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