Potassium ferricyanide and ammonium thiosulfate?

[MMfoto]

I'm just curious to know if you can use ammonium thiosulfate instead of plain "hypo" sodium thiosulfate, and if there would be any advantage to this. I use Formulary TF-4 for normal printing, and it just seems kinda odd to switch to sodium thiosulfate when bleaching, and then have to dust off the permawash.

I'm dependant on all you photo-chemists out there for smart answers, as my knowledge of chemistry has hovered around the high school level since, well, high school.

The MSDS for potassium ferricyanide states that it is: "incompatible with ammonia"

Thanks!

 

[gainer]

I can understand your worry about safety, though I don't know if it really is unsafe. I don't know why you should feel obliged to use permawash with the sodium thiosulfate. I seldom mix the ferri and the hypo, but use them separately, but I have used the TF4 as the hypo part. Maybe that's what is wrong with me..I'm dead and just thought I was getting old.

 

[MMfoto]

I can understand your worry about safety, though I don't know if it really is unsafe. I don't know why you should feel obliged to use permawash with the sodium thiosulfate. I seldom mix the ferri and the hypo, but use them separately, but I have used the TF4 as the hypo part. Maybe that's what is wrong with me..I'm dead and just thought I was getting old.

My "understanding" is that permawash provides an alkaline environment and that this helps in washing. I'm a little shaky on that, but that is roughly what someone at Photographers Formulary told me when I started using TF-4. My assumption has been that plain solutions of sodium thiosulfate and ammonium thiosulfate are acidic and basic respectively. On that basis I have used permawash on prints treated with sodium thiosulfate.

I've used TF4 as the hypo part too, after a water rinse, and I tossed it out afterwards. That's part of the reason I'm interested in using plain ammonium thiosulfate-to not waste TF4. I don't know if either are good ideas to use with ferri though, and I am interested in combining the ferri and the ammonium thiosulfate. An alkaline farmers reducer? But I tend to shy away from experimenting with chemistry I don't understand!

 

[Ole]

Plain solutions of ammonium thiosulfate and sodium thiosulfate are both alkaline.

Potassium ferricyanide is incompatible with ammonia - but there is a difference between ammonia and ammonium!

 

[MMfoto]

there is a difference between ammonia and ammonium!

I was waiting for that!

 

[BBMOR]

hello

if you use a mixture of Ferri/Thio for bleaching = Farmer formula it is impossible to catch up the picture again if the bleaching was to havy but by using a Ferri solutions on a well washed picture you can redevellope the picture again
just do not mix or put Ferri with strong acids
with chemicals never eat ,drink or smoke ,the first rule all chemist recieve on their first lab class

jm