How Safe Is Potassium Ferricyanide?

[Kirk Keyes]

Ferric vs. Ferrous:
Ferric = 3+ charge
Ferrous = 2+ charge

Potassium Ferricyanide:
3 K = 3+
6 CN = 6-
That means the iron has a 3+ charge to balance the potassium and the CN - so it is ferric.

Potassium Ferrocyanide:
4 K = 4+
6 CN = 6-
That means the iron has a 2+ charge to balance the potassium and the CN - so it is ferrous.

 

[dancqu]

I saw the effect of this in a series of prints in Tim Rudman's
book. Amazing and it sounded quite simple. Let us all know
how it goes. Thanks pentaxuser

I wonder, was Tim using the latent image bleach on negatives
or on the exposed but undeveloped print paper?

I've put up a 1% solution; 1.25 grams, 125ml. That will make
up into 12.5 to 125 liters of working strength. Plenty for tests.
At www.davidkachel.com/ - Choose from a large selection
of Davids writings. Click on history. Articles of interest
for almost every one. Dan

 

[pentaxuser]

I wonder, was Tim using the latent image bleach on negatives
or on the exposed but undeveloped print paper?

I've put up a 1% solution; 1.25 grams, 125ml. That will make
up into 12.5 to 125 liters of working strength. Plenty for tests.
At www.davidkachel.com/ - Choose from a large selection
of Davids writings. Click on history. Articles of interest
for almost every one. Dan

It was on the exposed but undeveloped print paper. In each case shown he got a clear improvement over the straight grade print.

pentaxuser