C41 Bleach

BMbikerider · May 19, 2023

With lack of availability of my normal C41 developing kits I changed over to Fuji Hunt 5 litre kits. The stability of the developer is superb in the concentrates but the Bleach bath working solution is a different matter The developer is made up each time I need to process a film but the bleach I make up as a half litre working solution. I have just ruined 3 x 35mm x 36 exp films because the bleach appears to have become exhausted quicker than what I would have normally expected. Am I being over optimistic as to how many films that can be bleached in half a litre of bleach working solution. The fixer stage appears to be working as normal (Seperate bleach and fixer).
In the initial mix I have processed 7 films 635mm and 1 x 120.

On the upside, the colour rendering on previous films was superb.

I say it is the bleach stage, because I re-bleached them in a fresh dilution and there was a slight improvement, but not enough to print normally, although they will scan and can be corrected using photoshop. Even the scans come out as having a strong reddish/orange tint.

Any thoughts?

koraks · May 19, 2023

BMbikerider said:
Any thoughts?

Probably not the bleach. I use Fuji C41 bleach and it's extremely economical, long-lasting and effective. Replenishment rate is around 20ml per 135 if memory serves; perhaps a little less. This means effective capacity of 50 rolls per liter, and I know for a fact that's on the (very) conservative side.

What kind of film have you been developing and could you post images of the scans and perhaps any RA4 prints you attempted? Perhaps this gives some clues as to where the problem is.

Also can you describe in detail your C41 process?

halfaman · May 19, 2023

Inssuficent bleach causes retained metallic silver. If there is any remaining metallic silver, re-bleaching and fixing with fresh solutions should eliminate it. If that is not solving the problem then I would doubt that it has anything to do with the bleach.

BMbikerider · May 19, 2023

To be honest this has taken me aback a little but my sequence is the same as I used to use with the Rollie Digibase C41 developer with slight differences in times as per the instructions included with the Fuji 5 l Kit.
All previous films both 35mm and 120 have been perfectly normal

The second column of times are those used in the Digibase kit Both development kits were carried out at 38c+/- .5 degree checked by a certified mercury thermometer. The process is carried out in a JOBO rotary processor
Timing is by a digital bench stop watch.

Fuji

Pre wash 5 mins
Developer 3.15 mins/secs
Rinse 2x30secs
Bleach 6.30 mins/secs
Rinse 7 x 30 secs
Fix 5 mins
wash 7 x 30 secs
Stabiliser 1.5 Mins

Digibase

Pre wash None
Developer 3.15 mins/secs
Rinse 2 x 30secs
Bleach 6 mins
Rinse 3 mins (6 x 30secs)
Fix 6 mins
wash 3 mins (6x 30secs
Stabilise 1 min

The films were then hung up to dry as per normal. The reason I gave an intermediate rinse between the developer and the bleach was to reduce the likelihood of the lid being blown off off due to gassing.

I don't think that there is any error on my behalf with the fixer which comes in a 1 litre bottle. I mix at 1 bottle plus 4 litres of water to give me 5 litres of working solution
The bleach comes in 1 x 2.5l bottle of concentrate so to make the full 5 litres I mix it at 1 to 1 water which will give me the 5 L stated quantity of working solution
With The Digibase and before that Agfa C41 which I used until Agfa went out of business for this process I never experienced anything like this in the 28 years or so, that I have been processing C41.

The only difference which stands out is your mention of replenishing the bleach which I never did nor was it suggested with all previous C41 'brews' I have used. I followed the suggestion of how many films could be processed in the kit and left it at that.

I did notice that when the film was wet ( a mixture of Fuji 200 and Kodak gold) the emulsion side had a yellowish brown colour that went to normal 'blackish' when the emulsion has dried.

Incidentally can ordinary B&W non hardening fixer be used with C41 film after the bleaching process?

koraks · May 19, 2023

BMbikerider said:
The reason I gave an intermediate rinse between the developer and the bleach was to reduce the likelihood of the lid being blown off off due to gassing.

I understand, but it is not the best approach. You're now effectively extending development by 30-60 seconds in an increasingly dilute developer (rinse water + developer carryover). It's unlikely to be the full explanation of your problem, but it's a poorly controlled factor that's introduced and not in accordance with any 'official' C41 process to the best of my knowledge. The extended development will introduce minor color balance shifts that may or may not be significant. Since you're an RA4 printer like me, I'd be concerned about this.

A better alternative IMO is to use a weak acetic acid (0.5-1%) stop bath. When using Jobo tanks, suppress the center part of the lid so that it can pop back into shape instead of the lid blowing off. It's designed this way for this purpose. If you don't overfill the tank with stop bath, it'll work OK. I do this all the time. The stop bath will effectively cut short development instantaneously.

BMbikerider said:
The only difference which stands out is your mention of replenishing the bleach which I never did nor was it suggested with all previous C41 'brews' I have used.

I just go by what the manufacturer says about the material in their tech. pubs and datasheets. In my case with the bleach I use, it is intended for replenishment and thus, I use it that way. I do use the developer one-shot as well as the fixer.

BMbikerider said:
I did notice that when the film was wet ( a mixture of Fuji 200 and Kodak gold) the emulsion side had a yellowish brown colour that went to normal 'blackish' when the emulsion has dried.

There is a very strong color shift in my experience between wet and dry film. I find it hard to judge the quality of still-wet negatives; there's often some kind of milky veil that completely disappears upon drying, and other color effects. To the best of my knowledge this is normal.

BMbikerider said:
Incidentally can ordinary B&W non hardening fixer be used with C41 film after the bleaching process?

Yes and no; ideally a near-neutral fixer is used at a pH of around 6.0-6.5 if memory serves. There is/was the risk of the dyes being forced into a leuco (colorless) state when subjected to acidity, such as when fixed in most (acidic) B&W fixers. However, I have the impression that most modern C41 films aren't very prone to this. You could neutralize a B&W fixer by adding e.g. ammonia solution while monitoring pH.

BMbikerider · May 19, 2023

Thanks for that, even after over 1/4 century of developing C41 I have never ever used a stop bath in the C41 process. I don't have any acetic acid but I do have acetic acid based stop bath which I use in both my RA4 and B&W developing. Is there any problem with using that? The normal dilutions are 1+4 for films (I assume they mean B&W) and 1+9 for papers. Obviously the 1+9 is the weaker one would that be a good starting point. How about Citric Acid based stop baths, would they work?

You never stop learning!

I appreciate your response, but having said that after I typed my reply, I thought what have I got to loose? So after kicking the Jobo into life once again and heating it up to somewhere around 38C I did the 5 min pre wet stage then re-fixed two strips of film again for 6.5 mins and they are now looking more like the negatives I would have expected.

You suggested to replenish the bleach with 20cc of fresh after each 35mm film, how about the fixer, would replenishing that also assist?

With RA4 printing, I always replenish the bleachfix and stop bath at the same rate as the developer - am I on the right track with replenishment when developing the film?

koraks · May 19, 2023

BMbikerider said:
Is there any problem with using that?

No, that should be fine. I usually use cleaning vinegar, which is around 7% acetic acid in my case. I just dilute it to the desired strength. Has always worked for me without fail for all color & B&W processes.

Dilution is not critical; anything between let's say 0.2% and 5% or so effective acetic acid concentration should be expected to work. There's no need to go beyond 1% or so, or even 0.5% if used one shot (which I'd recommend for this purpose).

It's best to not use odorless stop batch since that's citric acid and for some reason (unknown to me...I asked PE at some point but his memory was foggy on this one as well) that's a no go with color processes. Although admittedly I've tried it once or twice to no ill effect...

BMbikerider said:
You suggested to replenish the bleach with 20cc of fresh after each 35mm film, how about the fixer, would replenishing that also assist?

In my experience, the odds of the fixer going belly-up are way bigger than the bleach doing so. I personally use C41 Fuji rapid access fixer at a dilution of around 1+10 one shot with a fixing time of 3m15s at around 38C. This ensures I have a decent strength fixer that's always fresh and without unwanted sedimentation (this was the reason I adopted this approach). Replenished fixer should also work, but I don't know for how long the working stock will keep performing well. At some point it will start sulfuring out and then you're in deep trouble, since the sulfer will like to bind (a little) with the silver halide that results from bleaching and then you're essentially sepia toning your color negatives. That will result in color and density problems for sure. How bad they would be? I don't know...

BMbikerider said:
I always replenish the bleachfix and stop bath at the same rate as the developer - am I on the right track with replenishment when developing the film?

It's really best to refer to the datasheet specific to the product you use. In the Fuji chemistry I use, there is no direct correlation AFAIK between the replenishment rates for the different chemicals.

pentaxuser · May 19, 2023

BMbikerider, koraks has covered the point about stop bath after developer but for what it is worth I once wrote the instructions for Digibase C41 into my darkroom note book and the third step there is listed as a 30 secs acetic stop bath

I have a feeling that my list was compiled from a thread on Digibase where there was some mention by others that the Digibase instructions were not as comprehensive as they should be. So it may well be that Digibase makes no mention of stop bath but some posters ( probably PE principally amongst others) suggested it as an important step

What struck me when I look through the whole process is that compared to b&w the development time is very short but the whole process adds up to just under 25 mins

pentaxuser

Rudeofus · May 19, 2023

If you look at the reactions of bleach: it will deplete bromide and it will increase pH. As you raise pH of bleach above a certain point (somewhere around 7), the bleach will become mostly inactive. Lack of bromide will also make bleach weak (or even inactive), but that may happen much later than this destructive pH rise.

Therefore you already have 2 reasons to get concentrated Acetic Acid:

to use as a very cheap stop bath right after CD
to keep your bleach intact for much longer.

Target pH of this bleach is somewhere between 4 and 5. If you go too low, PDTA free acid will precipitate. If that happens, you can bring it back by adding Ammonia solution.

mtjade2007 · May 19, 2023

I have accumulated almost 2 gallons of used bleach. I took so much of it off for fearing the change of PH and lose of bromide. Is there a cheap (I mean simple) way to check the PH? Or just give it a few drops of acetic acid once in a while? Is there a way to replenish bromide so that this expensive and sometimes out of stock chemical can be rejuvenated? I don't have a chemistry background. I hope I don't have to waste the bleach.

The replies in this thread are right, the bleach isn't the cause of OP's issue. I don't use a stop step in between the development and the bleach. My bleach still lasts a very long time. I have used a liter of it for more than a year. I only top it up once in a while. I am not saying a stop step isn't necessary. I understand the benefit of it.

BMbikerider · May 19, 2023

When I started out,the Agfa C41 was straight forward without any complications, it was good and the concentrates never seemed to go off. The instructions were printed in an easy to read way but with non of the technicalities (Errrr stop bath etc) to complicate matters. Because it worked, I didn't see the need to change.

Agfa then went belly up as far as the home processor was concerned so it was Digibase which was actually quite good because the kits had bleach and fix included. Then that became more or less unobtainable so I tried Tetenal but didn't like it and now I use Fuji Hunt kit which is as good as the Agfa was.

Onwards and upwards as they say.

koraks · May 19, 2023

mtjade2007 said:
Is there a cheap (I mean simple) way to check the PH?

For bleach, the pH strips that are easily available through many outlets (including online) would be sufficient. Make sure you get strips that cover the entire relevant range; for instance, I've got some strips intended for ponds and aquariums that only cover a narrow range round pH 7. You want strips that cover let's say pH3 up to pH8 or so. Wider range is OK, narrower can be problematic.

BMbikerider said:
Agfa C41 was straight forward without any complications

One of the annoying things today is that with the chemistry aimed at labs, the documentation (if present to begin with) also caters to that audience. Fuji for instance publishes generally excellent information, but it's sometimes frustratingly difficult to locate the appropriate documentation, and once you've got it, it's generally a mass of stuff to wade through in the search of what applies to us, home users.

mtjade2007 · May 20, 2023

Thanks a lot, Koraks, for the suggestion of PH strips. Will give it a try soon.

mtjade2007 · May 20, 2023

BMbikerider said:
When I started out,the Agfa C41 was straight forward without any complications, it was good and the concentrates never seemed to go off. The instructions were printed in an easy to read way but with non of the technicalities (Errrr stop bath etc) to complicate matters. Because it worked, I didn't see the need to change.

Agfa then went belly up as far as the home processor was concerned so it was Digibase which was actually quite good because the kits had bleach and fix included. Then that became more or less unobtainable so I tried Tetenal but didn't like it and now I use Fuji Hunt kit which is as good as the Agfa was.

Onwards and upwards as they say.

Keep in mind that bleach and fix can be redone if a process did not get enough bleaching and fixing. So the only thing that could ruin the outcome of a film development is in the development step. I agree that the stop bath is not really needed. Just make sure the timer starts at the moment you start to pour the developer into the tank. Then make sure the developer is completely drained out and the bleach poured in exactly at the end of the 3 minutes 15 seconds time. You may want to begin the draining right at the 3 minutes point and pour in the bleach at the 3 minutes 15 seconds point. This is the standard of C-41. I don't think the Agfa developer you used is different.

brbo · May 20, 2023

I've been using that same FujiHunt X-Press C-41 kit and find the bleach virtually indestructible.

I used to mix 1L of working solutions of dev, bleach and fix at a time and reuse them for more rolls that Fuji advises. For 10 years I never used stop or wash between dev and bleach and never had a problem.

I now started using developer one shot (I mix the entire 5L and store the developer in coke bottles), but I still mix bleach and fix 1L at a time and reuse them. I've now opened my third kit since switching to one shot and discovered that I haven't even used up the entire bleach and fix from the first kit! I guess I'm lazy... But point is that I'm easily getting twice the stated output from bleach. I did start to use acetic acid stop (but that is in the hope to prevent uneven development that I sometimes get with 4x5" film).

Maybe something is wrong with your kit, but I wouldn't say that in general FujiHunt C-41 kit has a problem with bleach capacity.

koraks · May 20, 2023

brbo said:
acetic acid stop (but that is in the hope to prevent uneven development that I sometimes get with 4x5" film).

Have you tried a pre-wash? This makes a distinct difference for me on both 120 and 4x5 in Jobo tanks.

Stop bath isn't really necessary if bleach directly follows developer since the strongly buffered bleach acts as a stop bath. With jobo tanks it's annoying whenever the lid pops and part of the bleach is lost in the water jacket.

I also prefer a stop not to throw the bleach off too much into a higher pH. Once you get beyond the buffer range, pH will shoot up pretty fast. This can become a problem when extending the bleach into "unknown territory" (I plead guilty!)

brbo · May 20, 2023

koraks said:
Have you tried a pre-wash? This makes a distinct difference for me on both 120 and 4x5 in Jobo tanks.

Yes, I do that regularly now. Even for 135.

mtjade2007 · May 21, 2023

koraks said:
I also prefer a stop not to throw the bleach off too much into a higher pH. Once you get beyond the buffer range, pH will shoot up pretty fast. This can become a problem when extending the bleach into "unknown territory" (I plead guilty!)

Can you give the bleach a few drops of acetic acid to bring the pH lower back to where it is supposed to be?

mtjade2007 · May 21, 2023

Bleach can last a very long time but the fix does not. Some said it has twice the capacity of the developer. It is cheap so I'd replace it before it gives me trouble. I aerate my bleach every time before reusing it. It does work repeatedly for a long time without problems.

koraks · May 21, 2023

mtjade2007 said:
Can you give the bleach a few drops of acetic acid to bring the pH lower back to where it is supposed to be?

That would certainly work. For optimal safety I suppose the pH should be monitored, but personally I don't bother I have to admit. I just replenish more or less as prescribed and this seems to work ok

mtjade2007 · May 21, 2023

koraks said:
That would certainly work. For optimal safety I suppose the pH should be monitored, but personally I don't bother I have to admit. I just replenish more or less as prescribed and this seems to work ok

Both my thumbs up! Thanks, Koraks.

Radost · May 31, 2023

koraks said:
Probably not the bleach. I use Fuji C41 bleach and it's extremely economical, long-lasting and effective. Replenishment rate is around 20ml per 135 if memory serves; perhaps a little less. This means effective capacity of 50 rolls per liter, and I know for a fact that's on the (very) conservative side.

What kind of film have you been developing and could you post images of the scans and perhaps any RA4 prints you attempted? Perhaps this gives some clues as to where the problem is.

Also can you describe in detail your C41 process?

I taught it processes 100 films in 5 liters

koraks · Jun 1, 2023

Radost said:
I taught it processes 100 films in 5 liters

According to the Fuji CN16 docs Google turns up, the replenishment rate of CN16-Q NQ2-R bleach is 20ml per 135/24exp, so 30ml per 36exp. That's 33 films per liter. For N2-R from the 16FA, 16L and 16S product families, it's 5ml per 24 exp/7.5ml per 36 exp. or 133 films per liter. In both cases there's significant latitude if processing times are extended a bit. For instance, the official Fuji RA times for the bleach step are around 1 minute; I personally use 3m15 (same as C41 development).

sillo · Jun 3, 2023

A cheap aquarium air pump is another nice little tool to pick up for aeration.

pbromaghin · Jun 4, 2023

This year I had resolved to simplify my life and stick to B&W. Then this spring I was gifted a darkroom kit from a guy who did lots of color with a dichroic head and an electronic color analyzer. So I thought I could do color.

Now I read this thread. Oh my gawd, no way.

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