C-41 with ferricyanide bleach = out of focus images?

ruilourosa · May 30, 2016

I am having this problem of getting images outo of focus in a c-41 processing line that uses ferricyanide bleach...

Tested a lot and its not the camera nor the lens...

Could it be?

Thanks

Rui Lourosa

pdeeh · May 30, 2016

If you really mean Out of focus and not merely soft in some unspecified way, then
No.

Post some examples, otherwise we're all just going to be making stabs in the dark

ruilourosa · May 30, 2016

Well by out of focus i meant soft, or in french with flou, nothing was in perfect focus... i have not an image here, in BW no problems at all! i will also test in regular commercial c-41 service to check things out.

Jim Noel · May 30, 2016

I don't believe the bleach is causing the problem. Try permanganate bleach and see if you get the same result.

Rudeofus · May 30, 2016

C-41 films are not specified for and tested with Ferricyanide bleach, therefore in theory all bets are off. I have not read any reports so far where Ferricyanide bleach would damage C-41 stock, and you didn't specify which film you used.

RPC · May 30, 2016

Please post the process you used. I have used ferricyanide bleach with C-41 and so have others, with no problems. Unlike the official C-41 process, you MUST use a stop/clearing bath and wash between developer and a ferricyanide bleach, although I can't imagine failure to do so would cause the problem you are experiencing.

ruilourosa · May 31, 2016

Hello, i developed Ektar 100 in 120 with a bronica GS. I just wash (3 water changes with agitation) in between the developer and the bleach... Maybe it´s that...

Rudeofus · May 31, 2016

Ektar should be pretty robust, so I don't think it's damage to the emulsion that you are seeing here. Ferricyanide will oxidize carry over color developer the same way that exposed silver halide grains do, and the oxidized color developer will then react with color coupler to form dye.

For this reason people recommend a proper wash after color developer, followed by a sulfite clearing bath before the film enters the Ferricyanide bleach bath.

pentaxuser · May 31, 2016

Interesting link, thanks. I take it that under his point one of developer temperature the author means 20 mins at 20C and not 2 mins?

pentaxuser

RPC · May 31, 2016

pentaxuser said:
Interesting link, thanks. I take it that under his point one of developer temperature the author means 20 mins at 20C and not 2 mins?

pentaxuser

No. The RA Developer/Replenisher RT (for color paper) works well for 2 minutes @ 68F (20C).

RPC · May 31, 2016

Rudeofus said:
For this reason people recommend a proper wash after color developer, followed by a sulfite clearing bath before the film enters the Ferricyanide bleach bath.

The wash should follow the stop/clearing bath, not come before it. I use a 2% acetic acid stop with 10g/l of sodium sulfite then the wash, then the ferricyanide bleach.

Rudeofus · May 31, 2016

RPC said:
No. The RA Developer/Replenisher RT (for color paper) works well for 2 minutes @ 68F (20C).

I think there is confusion between Kodak's C-41 RA chemistry and Kodak's RA-4 process. Yes, I can imagine well that RA-4 CD works on RA-4 paper within 2 minutes at 20°C/68°F, but AFAIK Kodak's C-41 RA CD works as fast as regular C-41 CD, and in this case 2 minutes would be insufficient at 20°C.

If you scroll down to user comments in that PN thread, Rowland Mowrey clears up this confusion himself: he meant RA-4 chemistry acting on RA-4 paper, and the 2 minutes at 20°C number is likely correct.

pentaxuser · May 31, 2016

Thanks, Rudeofus. My assumption which was quite mistaken was that the article was solely on C41 but it was in fact myths about colour processing of C41 and RA4 and the author's point 1 was about RA4 which quite rightly is 2 mins at 20C

pentaxuser

David Lyga · Jun 17, 2016

I ALWAYS use potassium ferricyanide with the C-41 process. However, I do this: develop, stop, then fix. Then in room light, bath in a combination of potassium ferricyanide (PF) and film strength fixer.

The PF I mix as follows: 1g PF for each 25mL of water. This makes the bleach and keeps indefinitely. When mixed (1 bleach +1 film fixer), the solution lasts about 20 minutes. NO PROBLEMS whatsoever, and this blix can be performed in roomlight. - David Lyga

Gerald C Koch · Jun 17, 2016

The only thing that might be mistaken for images being out of focus and could be caused by processing would be reticulation. However with modern pre-hardened emulsions even this is unlikely unless the film was really abused. But without sample scans and details about the processing there is no way of determining this. I assume that there is no evidence of improper bleaching and fixing.

Photo Engineer · Jun 17, 2016

Ferricyanide is NOT a problem here. It does not cause blurry images.

PE

C-41 with ferricyanide bleach = out of focus images?

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