RA4 fixer part - formula?

[mshchem]

I think if you mix it all up it will keep a lot better. That's what I will do next time. I was using mixed blix from the same bottle of concentrate long after the concentrate went bad.

Yep this is my plan . According to Kodak this is due to O2 I opened the bottle and out went the nitrogen blanket . My local connection , Lori at PHOTO PRO in Cedar Rapids IA saved my day .
Best Mike

 

[mshchem]

TF-5 is very similar to both the C41 and RA4 fixer components. They all should keep for about 5 years or so. I have some on the shelf that old that are still OK.

PE

I have absolutely no problem with Kodak Flexicolor C-41 fixer, or Kodak rapid fix, I once had an antique bottle of Ilford that formed sulfur . According to CIS-167 by the "original EKCo " thiosulphates oxidize to sulfur and H2S, the sulfide reacts with silver etc. I think this is a especially vulnerable formulation . If I could buy Alaris chemistry packaged as it is in the EU I would. I can't find anything other than the dopey cartridges over here . I should just stop fiddling with color printing . I think I'm clinging to the familiar and maybe my youth . I am relaxed when I'm printing . It's a comfort , I have to smuggle some back from France . Man wouldn't Trump have a fit about that

 

[Wayne]

Yep this is my plan . According to Kodak this is due to O2 I opened the bottle and out went the nitrogen blanket . My local connection , Lori at PHOTO PRO in Cedar Rapids IA saved my day .
Best Mike

I'm pretty sure i used nitrogen after i opened the concentrate too.

 

[mshchem]

I'm pretty sure i used nitrogen after i opened the concentrate too.

I use butane from my wife's micro torch (not lighted) but I thought it's fixer . My mistake . Oxygen shows no mercy.
Mike

 

[Rudeofus]

There are some important challenges when formulating a two part BLIX. Ammonium Ferric EDTA will precipitate EDTA free acid if pH is too low, so the concentrate part with the Ammonium Ferric EDTA has to be alkaline to neutral. I don't know exactly which exact Kodak product was used here, but one example taken from Kodak's MSDS library called "KODAK EKTACOLOR RA-4 Bleach Fix and Replenisher NR Part B" lists a pH of 7.1 for that part. Apparently they can't go much lower for the reasons stated, and EDTA is not only a good buffer and also present in high amounts.

The whole BLIX should reach pH 6.5 when mixed, and with the bleach part neutral to alkaline, the fixer part must be acidic - plenty acidic. The MSDS for "KODAK EKTACOLOR RA-4 Bleach Fix and Replenisher NR Part A" states a pH of 5.3, which is lower than typical rapid fixer. Fixers at low pH don't have a very long shelf life, so your observations don't come as a surprise. I've seen the same thing with BLIX concentrates from other makers, there are common threads here about Tetenal BX2 going bad, for the very same reasons. Inert gas blanket can help, assuming the bottle doesn't let oxygen through.

AFAIK there is a C-41 BLIX kit which uses three concentrates, one with Ammonium Ferric ETDA, the second one with Ammonium Thiosulfate, the thord with Acetic Acid to get pH to 6.5. These concentrates should last much longer, but shelf life was apparently no concern for minilab chemistry.