Potassiume ferricyanide bleach, blueish-black spots

Fraunhofer · Mar 11, 2018

I am using a bleach of about 3.5g potassium ferricyanide and 3.5g KBr and once in a while find very small <1mm blueish-black spots afterwards, like these

What could that be?

georgegrosu · Mar 11, 2018

Films should be well soaked before slimming.
The slimming solution must be well dissolved.
The blue color shows the presence of iron ions in solution.

George

Doremus Scudder · Mar 13, 2018

I don't know what slimming film is... I want mine fatter anyway And I assume you are bleaching prints here.

But George is right; blue spots are due to iron contamination. It could be from your water or some other source. Try using a particle filter for your water and switch to distilled for mixing the bleach itself.

Best,

Doremus

Fraunhofer · Mar 13, 2018

Doremus Scudder said:
I don't know what slimming film is... I want mine fatter anyway And I assume you are bleaching prints here.

But George is right; blue spots are due to iron contamination. It could be from your water or some other source. Try using a particle filter for your water and switch to distilled for mixing the bleach itself.

Best,

Doremus

Thanks, iron seems plausible. We’re on a well and our water filter always comes out a deep rust red... so distilled water is the way to go.

Potassiume ferricyanide bleach, blueish-black spots

Fraunhofer

georgegrosu

Doremus Scudder

Fraunhofer

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