Potassiume ferricyanide bleach, blueish-black spots

[Fraunhofer]

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]

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]

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]

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.