[Alt-photo] Sodium Thiocyanate For Fixing Out Lumens

Andy Duncan duncanad45 at gmail.com
Mon Aug 14 18:00:53 UTC 2017


Hi all,

I’m experimenting with different ways of fixing lumen prints, and read
somewhere (I think in a thread on apug.org) that sodium thiocyanate can be
used to fix out prints. I've used Ilford Rapid Fix in the past, but my main
fixer in recent years has been TF-4 from Photo Formulary, which is what I
use for my film. The color shifts from both were pretty similar, both being
ammonium thiosulfate. I began using the sodium thiocyanate recently, and
after my last batch of prints, I noticed that after processing, some of the
prints continued to darken. I processed in a 5% dilution for 1-2 minutes (I
don't get real scientifically accurate with my times when processing
lumens...maybe that's part of my problem); the source I first read that
mentioned using sodium thiocyanate gave a 10% dilution. So my question is
this: is sodium thiocyanate as permanent of a fixer as the other fixing
agents in TF-4 and Ilford Rapid Fix?

I was also wondering if any of the chemists out there could explain in
layman's terms the difference between sodium thiocyanate and ammonium
thiosulfate? What is the effect each has on image permanence and
stabilization?

I suppose I should add that I'm not afraid of the color shifts that occur
after fixing a lumen print, nor are they unwanted. On the contrary, I tend
to welcome them. I just want the lumen to be as permanent as I can make it.
I'm starting to prefer the shifts that occur with the sodium thiocyanate
over those that occur with TF-4, so I'd like to make sure they'll be as
stable when processed in TF-4. I have prints that are 10+ years old that
have had no further shift in color/intensity/brightness after being hung on
my walls. These recent ones shifted only hours after being taken off my
drying racks.

Thanks in advance!
Andy


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