C41 need to re bleach/fix?

henryyjjames · Jul 10, 2023

Hey all,

So I developed three rolls of colour film with chemistry that I had opened and used lightly a few days prior, but the last set of negs came out looking a little milky/clouded. Correct me if I'm mistaken, but I think this means they are under-bleached/fixed due to the chemistry being exhausted. Unfortunatley, I don have any more chemistry to make fresh bleach/fix and re-fix them. Is there anything I can do in the meantime? Any substitute? I don't thin there is but no harm in asking. Do you think the film will be ok till I get in new chemistry to fix it?

Thanks!

mshchem · Jul 11, 2023

You can use any fixer. I've used ordinary rapid fixer to fix C41. If the negatives are questionable a little extra fixing won't hurt.

halfaman · Jul 11, 2023

It has been described by PE and others here that dyes hues are dependant of fixer pH. That is the reason why all C41 fixers (and blixes) are close to neutral (6.5). So an ordinary BW acidic fixer would be not advisable.

foc · Jul 11, 2023

Are they milky/cloudy looking when the negatives are still wet or dry?

There is no harm in re-bleaching and re-fixing them, remember you can't over bleach or fix so you won't do any harm.

Maybe post an image of the milky/cloudy negatives, that might help with the advice.

koraks · Jul 11, 2023

halfaman said:
It has been described by PE and others here that dyes hues are dependant of fixer pH.

Sort of, as I understand. The problem doesn't seem to be there with modern C41 dyes, though. It used to be an issue with certain old dues that they would revert to a leuco state at acidic pH's - in this state they're colorless, so appear to be missing or have lower than anticipated density. I've never gotten modern film (or paper) to do this. I don't believe that modern photographic dyes actually shift hue depending on pH, though.

Of course, it's good practice to use a C41 fixer with C41 film. But in a pinch, it won't hurt to try any old B&W fixer (as long as it's a rapid one).

halfaman · Jul 11, 2023

koraks said:
Sort of, as I understand. The problem doesn't seem to be there with modern C41 dyes, though. It used to be an issue with certain old dues that they would revert to a leuco state at acidic pH's - in this state they're colorless, so appear to be missing or have lower than anticipated density. I've never gotten modern film (or paper) to do this. I don't believe that modern photographic dyes actually shift hue depending on pH, though.

I am not talking about dyes stability. The change from initial leuco state to a particular final dye hue is indeed pH dependant.

Can ferricyanide / Dichromate bleach be used in C-41?

I've recently become interested in home-processing color film, as I've rediscovered that color can actually be nice and useful [sometimes]. However, commercial processing can get expensive. So anyway ... The developer seems to be fairly inexprensive; concentrate to make 1 gallon of Flexicolor...

www.photrio.com

Blix for ECN, C-41 and E-6

Praise Cthulhu! Here's a Blix recipe that's worked for me with ECN, C-41 and E-6. Distilled water - 700ml. Amm Thiosulfate - 150g Sod Carbonate - 8g Na Fe EDTA - 58g Sod Sulfite - 17g PDTA - 13g Mercaptotriazole - 100mg. Distilled water to make 1000ml. In my experience, the above formula...

www.photrio.com

The typical range for a C41 fixer ph is 6.5 +/- 0.5.

koraks · Jul 11, 2023

halfaman said:
I am not talking about dyes stability.

I know, neither am I.
Where is the evidence that contemporary C41 dyes will shift hue depending on pH? I don't doubt that certain dyes do this - it's well known and the basis for e.g. litmus tests etc. But I've seen no evidence that modern dyes in C41 film (or RA4 paper for that matter) are pH sensitive in terms of hue angle.

halfaman · Jul 11, 2023

koraks said:
I know, neither am I.
Where is the evidence that contemporary C41 dyes will shift hue depending on pH? I don't doubt that certain dyes do this - it's well known and the basis for e.g. litmus tests etc. But I've seen no evidence that modern dyes in C41 film (or RA4 paper for that matter) are pH sensitive in terms of hue angle.

No hard data on my side pointing at any direction. To be skeptic or cautious about it is a decision for everyone, like other aspects of the photographic process (and life). With the information I have I decide to be cautious.

koraks · Jul 11, 2023

That's fair enough. I can only say I never noticed any ill effects if occasional treatment of C41 film with acidic fixers. With the good availability of appropriate C41 fixers, there's no real need to go there, though.

henryyjjames · Jul 11, 2023

foc said:
Are they milky/cloudy looking when the negatives are still wet or dry?

They were milky looking (and slimier?) when wet. I'll look at them tonight. They are dry now; I just haven't touched them yet. What bothered me is that the first films I did the other night didn't look this way, and they were all Fuji stock.

henryyjjames · Jul 11, 2023

foc said:
There is no harm in re-bleaching and re-fixing them, remember you can't over bleach or fix so you won't do any harm.

Yea, it was always my plan to re-fix them, but I didn't know if there was something I could substitute or do in the meantime before the new chemistry comes. I accidentally ordered four kits instead of two. Oops. At least I'll be prepared

Rudeofus · Jul 11, 2023

henryyjjames said:
They were milky looking (and slimier?) when wet. I'll look at them tonight. They are dry now; I just haven't touched them yet. What bothered me is that the first films I did the other night didn't look this way, and they were all Fuji stock.

Many E-6 films look awful when wet. E100VS looks brown when wet, other films look blue or milky, and when processing was correct and the film is dry, all these flaws magically disappear.

If you are concerned about incorrect bleaching or fixing and have access to a film scanner, then you can use IR histogram to guestimate the amount of retained silver. Film dyes are mostly transparent to IR light, whereas silver is not. Properly processed film should have at least 90% translucency in IR band.

PS: "slimy" film surface is often an indication of insufficient washing.

mshchem · Jul 11, 2023

Rudeofus said:
Film dyes are mostly transparent to IR light, whereas silver is not

I discovered this by chance, I was loading some film reels with my toy (but effective) IR goggles. I glanced over at a couple of strips of 120 film, (processed) hanging from a previous session. Color negative was pretty much transparent, I could see images on a black and white film.
The emulsion side of unprocessed film looks brilliant white on IR screen. I've always wondered how real old school IR film got around this?

lamerko · Jul 12, 2023

I got hold of a tube of ammonium thiosulphate - it's relatively cheap. An approximately neutral formula for ECN-2 is very simple. Its pH is the same as Ron's formula, and overall the differences are insignificant. Specifically, in the ECN-2 development document, there is the following explanation regarding pH:

the fixer pH should never be allowed to fall below 5.5, since low fixer pH affects the dye stability of Kodak color negative films.

Rudeofus · Jul 12, 2023

lamerko said:
Specifically, in the ECN-2 development document, there is the following explanation regarding pH:

Interesting find! So may be dyes show different tendency towards oxidation depending on their protonization status, even if they maintain their hue.

C41 need to re bleach/fix?

henryyjjames

mshchem

halfaman

foc

koraks

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halfaman

Can ferricyanide / Dichromate bleach be used in C-41?

Blix for ECN, C-41 and E-6

koraks

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halfaman

koraks

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henryyjjames

henryyjjames

Rudeofus

mshchem

lamerko

Rudeofus

C41 need to re bleach/fix?

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