Does Ferricyanide bleach exhaust? If so when?

GBS · Jul 10, 2020

Hi!

I'll be starting some ECN-2 tests at the end of the month and will likely adjust the Ferricyanide bleach mixture for some C-41 while I'm at it.

I've read and searched for hours, but am still unclear. I know there's a bleach that "doesn't exhaust," but there are a few bleach mixes and I'm struggling to get clear on this one.

Does Ferricyanide bleach exhaust? If so, what's the exhaustion rate? Does it benefit from air/shaking to keep it alive?

Is there a concern that Ferricyanide bleach will negatively affect negative life?

Thanks a ton!

David Lyga · Jul 10, 2020

Ferricyanide bleach seems to be good forever. Just don't keep it in a lot of light, like sunlight. Mixed with fixer it dies within 15 minutes to a couple of hours, depending upon dilution, the weaker the combination is, the longer the two combined last. - David Lyga

Mr Bill · Jul 10, 2020

GBS said:
I've read and searched for hours, but am still unclear. I know there's a bleach that "doesn't exhaust," but there are a few bleach mixes and I'm struggling to get clear on this one.

Hi, I doubt there is a bleach that doesn't exhaust. But if you use one of the "ferric ammonium EDTA" (or PDTA?) types the "bleaching power" can be restored by aerating it. Commercially there would be a "sparger" in the processor, bubbling air through the bleach. For home use one could shake up some bleach in an oversized bottle, or even just pour it back and forth between containers (trying to make it a little "violent," pouring from higher up, etc., to bring some air into the mix).

As a note, these bleaches also contain some bromide, which recombines with the silver as it is "bleached." So if you are not using a replenisher then they can eventually run out of bromide ion, and things will stop working. Continued aeration won't help this.

I don't know much about the ferricyanide bleach, but I don't think aeration would work. It needed some sort of special treatment. I'm pretty sure they cover this somewhere in the H-24 manual if you can deal with the depth of information.

[Update: the H-24 manual gives several procedures for dealing with the ferrocyanide; essentially it can be oxidized (restore bleaching power) back to ferricyanide in at least three ways. One is to use a chemical oxidizing agent (persulfate), another is treating with ozone, and a third way is via electrolysis. So I take it that simple aeration would not help.]

[Continued update: and of course Donald (in post below) is right about the bromide]

Donald Qualls · Jul 10, 2020

You'd need to supply, and replenish, the bromide in ferricyanide bleach, also. The halide being recombined with developed silver has to come from somewhere.

Pixophrenic · Jul 10, 2020

I don't think,even though it's just an opinion, that there is a rational way to replenish a ferricyanide bleach. Historically, it was abandoned exactly because its regeneration and/or replenishment could not be practical. It is true that a halide needs to be supplied, but so does the ferricyanide. If any serious research has ever been done on this subject, it was considered proprietary. The respective chapters in Mason and Haist are characteristically terse. IMHO, in the absence of solid data, the safe path is just not get greedy and use the same solution less than 3 times. After all, it gets contaminated with the previous solution, apart from getting exhausted. Mason warns that if the pH of the bleach gets too low, some deadly cyanide gas is going to emanate from the solution. I am not sure, though, that this remark of his was directed at those who would like to drive the bleach to its imminent exhaustion.

Raghu Kuvempunagar · Jul 10, 2020

Pixophrenic said:
I don't think,even though it's just an opinion, that there is a rational way to replenish a ferricyanide bleach.

If you look at Kodak SR-29 bleach, which is a ferricyanide-bromide bleach used for ECN-2, it has a replenisher associated with it. It's recommended to add certain volume of the replenisher after each roll.

GBS · Jul 10, 2020

Mr Bill said:
[Update: the H-24 manual gives several procedures for dealing with the ferrocyanide; essentially it can be oxidized (restore bleaching power) back to ferricyanide in at least three ways. One is to use a chemical oxidizing agent (persulfate), another is treating with ozone, and a third way is via electrolysis. So I take it that simple aeration would not help.]

Thank you, Mr. Bill. You also mentioned H-24 to me in the other post. I was only familiar with the recipes in module 7 until now. I appreciate you taking the time not only to share the document, but help me pinpoint the the relative information.

Donald Qualls said:
You'd need to supply, and replenish, the bromide in ferricyanide bleach, also.

Thank you, Donald.

Can you answer a couple questions in basic terms--if possible?

1- what's the exhaustion rate of ferricyanide bleach when using a stop and clearing rinse after developer?
2- Is there a 'basic' replenisher mix/process?
I am looking at 5-11 to 5-19 in H-24 and what's laid out there is over my head.

(side question: the ferracyanide bleach seems to be common for ECN-2 home kits because it's easy to source everything to make a true recipe. Does it make more sense in the long run to use one of the others? And if so, which one? I see some ingredients in the bleach recipies on 7-30 to 7-32 that I'm not familiar with (like Proxel GXL, and KODAK Chelating Agent No. 1). Whatever the mix, I'd like it to be as close to "stock" as possible.

Thanks a lot!

GBS · Jul 10, 2020

Raghu Kuvempunagar said:
If you look at Kodak SR-29 bleach, which is a ferricyanide-bromide bleach used for ECN-2, it has a replenisher associated with it. It's recommended to add certain volume of the replenisher after each roll.

Thank you! I haven't yet found that info, but I'll admit: I was mostly focused on the recipes. I'll have a look.

Update: I did read through that. Table 7-2 sends you back to Module 5-11 through 5-19. I was unable to deduce a general answer to the exhaustion rate. Unless simplified, the replinisher methods are over my head. I could possibly figure out the Persulfate method. But that's a big "if." As far as reaction rate, that seems to be discussed in a scientific journal outside the publication (see "reaction rate" at the bottom of 5-13. Is that the same thing as exhaustion rate?

Barring any replenishing, even if I have to take the old solution to the hazardous waste and start over, when do I know it's exhausted?

Mr Bill · Jul 10, 2020

Pixophrenic said:
I don'ton't think,even though it's just an opinion, that there is a rational way to replenish a ferricyanide bleach. Historically, it was abandoned exactly because its regeneration and/or replenishment could not be practical.

No, that's not so. The predecessor to the C-41 film process was C-22, which DID use a ferri/ferro bleach. We ran loads of it at the place where I worked. I was just a wet-behind-the-ears youngster learning the ropes of QC, setting processor replenishment rates and reading control strips, etc., so I didn't known much about the chemical regeneration process. That was handled between our onsite chem lab and the chem mixing department. But most definitely it was normal for processing labs to replenish and to regenerate ferri/ferro bleaches.

My understanding is that a major concern was ecological, and that the ferric ammonium EDTA bleach was much more benign, but I don't have any good references about this. I'd bet that if you looked up some patent references, try one of Ron (Rowland) Mowrey's on blix, etc., the section often called "background of the invention" would reference such things. Mason and Haist are probably not the best sources on this; there is probably a lot of info in older issues of journals of the Society of Photographic Scientists and Engineers. But you'd probably have to go to a photography specialist university, or the like, for this.

And Raghu's link shows a current usage.

As a note, I wonder if you have a misunderstanding of what "replenishment" is. In photofinishing lingo a "replenisher" is a sort of extra-strength version of a chemical bath (such as developer or bleach) that can be added to a working bath, in such a way that it counteracts the effects of usage. For example, with a developer the developing agent is gradually used up. So in a developer REPLENISHER, the developing agent is present at an extra-high concentration. This makes it possible to use a smaller quantity of REPLENISHER to restore a working tank solution of developer to its original strength.

GBS · Jul 10, 2020

Mr Bill said:
And Raghu's link shows a current usage.

I did my best to sift through that, modules 7 p30-32 and 5 p11-19. I do understand replenisher, though in this case I guess it could be called "rejuvenation"?

Either way, I want to know when and how to revive it, or when to know it's time to toss if revival is out of the question for my skill level. Again, thanks for everyone's time. I'm doing my best.

Mr Bill · Jul 10, 2020

GBS said:
I did my best to sift through that, modules 7 p30-32 and 5 p11-19. I do understand replenisher, though in this case I guess it could be called "rejuvenation"?

Sorry, I had meant that for Pixophrenic.

In the industry the term for rejuvenating a chemical is "regeneration." So loosely, the chemical you use to process film is called the "working tank solution." As it gradually becomes exhausted you can bring it back into spec by adding the extra-strength version called "replenisher." Then, if you collect the waste chemical (for certain chemicals) you can treat it and then add a "regenerator" mix, which turns it back into replenisher.

GBS · Jul 10, 2020

Mr Bill said:
In the industry the term for rejuvenating a chemical is "regeneration." So loosely, the chemical you use to process film is called the "working tank solution." As it gradually becomes exhausted you can bring it back into spec by adding the extra-strength version called "replenisher." Then, if you collect the waste chemical (for certain chemicals) you can treat it and then add a "regenerator" mix, which turns it back into replenisher.

Ah, super. that makes sense! I'm also tired and hungry.

I want to know when and how to rejuvinate ferricyanide bleach, or when to know it's time to toss if rejuvination is out of the question for my skill level.

Thank you

Raghu Kuvempunagar · Jul 11, 2020

GBS said:
Thank you! I haven't yet found that info, but I'll admit: I was mostly focused on the recipes. I'll have a look.

Update: I did read through that. Table 7-2 sends you back to Module 5-11 through 5-19. I was unable to deduce a general answer to the exhaustion rate. Unless simplified, the replinisher methods are over my head. I could possibly figure out the Persulfate method. But that's a big "if." As far as reaction rate, that seems to be discussed in a scientific journal outside the publication (see "reaction rate" at the bottom of 5-13. Is that the same thing as exhaustion rate?

Barring any replenishing, even if I have to take the old solution to the hazardous waste and start over, when do I know it's exhausted?

Table 7.2 says that SR-29 bleach replenishment rate is 200ml of replenisher per 100 feet of 35mm film which translates into 11g of Ferricyanide and 7g of Bromide. The replenishment volume for 400 feet of film brings in approximately same amount of Ferricyanide and Bromide present in 1000ml of the bleach. Make what you will of this.

When you said "exhaustion" did you mean A) exhaustion due to repeated use or B) exhaustion due to ageing when left unused for a long time? If it is A then SR-29 bleach replenishment might work for you. If it is B, then ferricyanide bleach is known to remain potent for long time if stored properly but perhaps not indefinitely.

Mr Bill · Jul 11, 2020

GBS said:
s far as reaction rate, that seems to be discussed in a scientific journal outside the publication (see "reaction rate" at the bottom of 5-13. Is that the same thing as exhaustion rate?

No, that reaction rate seems to be the rate of persulfate oxidizing the ferrocyanide back to the active form, ferricyanide. This would be a first step toward regerating waste bleach. I don't think you want to go there, though, because you would need to also do some chemical analysis, etc.

I'd say that your best bet would be to either have a single container of bleach that you use until it starts going bad (I don't have a good way for you to determine that), or to use a replenisher, ie, for each roll you add some quantity of it to your working tank. As you do this you'll build up an excess of volume; the surplus volume then becomes waste for disposal.

The saving grace of overused bleach is that the film can be rebleached (and fixed, etc) and it will be fine.

As a note the replenishment rate that Raghu quote is most likely for a machine that squeegees the film between baths (you'd have to read the text to confirm). You probably won't be using a squeegee so that a higher replenishment rate should be used (the wet film coming into the bleach dilutes it). But in practical terms, that bleach is probably strong enough that the excess dilution is probably not too important.

AgX · Jul 11, 2020

Mr Bill said:
In the industry the term for rejuvenating a chemical is "regeneration." So loosely, the chemical you use to process film is called the "working tank solution." As it gradually becomes exhausted you can bring it back into spec by adding the extra-strength version called "replenisher." Then, if you collect the waste chemical (for certain chemicals) you can treat it and then add a "regenerator" mix, which turns it back into replenisher.

Thank you for this digression into terminology.

mohmad khatab · Jul 11, 2020

Mr Bill said:
Sorry, I had meant that for Pixophrenic.

In the industry the term for rejuvenating a chemical is "regeneration." So loosely, the chemical you use to process film is called the "working tank solution." As it gradually becomes exhausted you can bring it back into spec by adding the extra-strength version called "replenisher." Then, if you collect the waste chemical (for certain chemicals) you can treat it and then add a "regenerator" mix, which turns it back into replenisher.

Why do you want a constant renewal to infinity?
You should get rid of him without regreting ..
I keep it somewhere with a swamp full of insects and rodents ,, this is the best help for the environment.
Then I prepare a completely new bleach solution.
- What is the problem ..?
Do you feel sad when you get rid of used bleach solution?
Why do not you feel this sad when you get rid of the consumer developer.?
You must get rid of old chemical solutions when you feel that they have produced the film quantities that you must actually produce.
Life must go and feel that there is a crew of new solutions that is somewhat happy.

Mr Bill · Jul 11, 2020

mohmad khatab said:
Why do you want a constant renewal to infinity?
You should get rid of him without regreting ..

mohmad khatab said:
Do you feel sad when you get rid of used bleach solution?
Why do not you feel this sad when you get rid of the consumer developer.?

Yes I feel sad to throw away used chemicals when I know they have much life still left in them.

Would you have me throw away all of the food left after a meal? When I know that I can easily save the extra food and eat again the next day.

Or if I buy new clothes and they become dirty, would you have me throw them away and buy more? When I could very easily wash them to a like-new appearance and wear them again. Is that not wasteful?

So why must I throw away my chemicals when I know that I can easily repair them and use them again?

Momad, I must confess that I'm speaking to you in humor, to pretend as if you are wasteful, which I know that you are not.

On a serious note, my experience is from a photofinishing lab where we used over 5,000 gallons of replenishers every day. That is about 20,000 liters per day. So we have the opportunity to reuse some of this, why not? Everything we can reuse is something that doesn't have to be disposed of, and something that doesn't have to be bought new. And so the money saved can go to pay employees (but more than likely to company profit).

Now this sort of saving is not for everyone, because it takes extra labor and equipment to do it. So you don't want to spend five dollars of work to save one dollar of chemicals. But if your five dollar of work can save, say, five HUNDRED dollars of chemicals, then shouldn't you do it? (Of course you should.)

As a very rough estimate, comparing a typical user of mix-it, use-it, and throw-it-away photo chemicals versus a commercial lab using best practices of replenishment, use of squeegees after every tank, and regenerating bleach and fix, I would say that the commercial lab can have a chemical cost, per roll, about ten times lower. Note that I did not specifically calculate this, just a rough guess from past experience.

GBS · Jul 11, 2020

Raghu Kuvempunagar said:
Table 7.2 says that SR-29 bleach replenishment rate is 200ml of replenisher per 100 feet of 35mm film which translates into 11g of Ferricyanide and 7g of Bromide. The replenishment volume for 400 feet of film brings in approximately same amount of Ferricyanide and Bromide present in 1000ml of the bleach. Make what you will of this.

When you said "exhaustion" did you mean A) exhaustion due to repeated use or B) exhaustion due to ageing when left unused for a long time? If it is A then SR-29 bleach replenishment might work for you. If it is B, then ferricyanide bleach is known to remain potent for long time if stored properly but perhaps not indefinitely.

Oh wow. I was scouring module 5 until late last night, which is full of fairly advanced chemistry. And there it was in simple terms in module 7. Thanks a TON for distilling that info and sharing it with me. I fell like I leapt light years towards my understanding of what I have and what I can do (feasibly). Thanks a lot. I'm embarrassed that the replenishment info was easy to find and I missed it.

In answer to your A/B question: both. But you answered them: the mix will last for a while, and the replenishment is laid out in your reply. Thanks a ton!

Mr Bill said:
As a note the replenishment rate that Raghu quote is most likely for a machine that squeegees the film between baths (you'd have to read the text to confirm). You probably won't be using a squeegee so that a higher replenishment rate should be used (the wet film coming into the bleach dilutes it). But in practical terms, that bleach is probably strong enough that the excess dilution is probably not too important.

Excellent point! Thank you. I'll be using a stop bath and clear water rinse to help keep the bleach uncontaminated.

Pixophrenic · Jul 11, 2020

Mr Bill said:
Sorry, I had meant that for Pixophrenic.

In the industry the term for rejuvenating a chemical is "regeneration." So loosely, the chemical you use to process film is called the "working tank solution." As it gradually becomes exhausted you can bring it back into spec by adding the extra-strength version called "replenisher." Then, if you collect the waste chemical (for certain chemicals) you can treat it and then add a "regenerator" mix, which turns it back into replenisher.

Wow, this is getting to become and interesting thread. Would Mr Mowrey please pitch in? In industry, when it is meant that a solution is "regenerated, replenished, rejuvenated", and so on, it is also meant that there is a test method to determine that this procedure restored (more or less) the original property, such as the treatment time, of the solution. I understand that someone would feel inclined to reproduce an industrial practice in a home setting, but what is the point at such scale? I can imagine a test for exhaustion, wherein a fogged and developed (in a BW developer) test strip can be pre-made, and then small clips of it bleached and fixed and found to be blank (or faint yellow). This test would tell you how close you are to spoiling your valuable film.

GBS · Jul 11, 2020

Pixophrenic said:
Wow, this is getting to become and interesting thread. Would Mr Mowrey please pitch in? In industry, when it is meant that a solution is "regenerated, replenished, rejuvenated", and so on, it is also meant that there is a test method to determine that this procedure restored (more or less) the original property, such as the treatment time, of the solution. I understand that someone would feel inclined to reproduce an industrial practice in a home setting, but what is the point at such scale? I can imagine a test for exhaustion, wherein a fogged and developed (in a BW developer) test strip can be pre-made, and then small clips of it bleached and fixed and found to be blank (or faint yellow). This test would tell you how close you are to spoiling your valuable film.

@Pixophrenic Thank you. To be brief: I'm not trying recreate the full industrial scale. I am, however, trying to understand what I am capable of at home with regard to
A) how much film can 1L of bleach effectively process
B) how realistic/effective is it to regenerate vs. tossing and starting over (I prefer conservation in general, but understand that in some cases, that may be unrealistic)
@Raghu Kuvempunagar's reply seemed to be what I needed to know, as a starting point at least. Link here

Pixophrenic · Jul 11, 2020

Raghu Kuvempunagar said:
If you look at Kodak SR-29 bleach, which is a ferricyanide-bromide bleach used for ECN-2, it has a replenisher associated with it. It's recommended to add certain volume of the replenisher after each roll.

Sure, but it does not mean it is rational. It apparently "just works". However, talking further in this direction would hijack the thread. Having compared various published historical ferricyanide bleaches, I came to the conclusion that there is nothing "rational" about them beside them being a buffered mixture of ferricyanide and bromide, with actual concentrations being quite arbitrary. The lingering problem with such bleaches was (also) that a slight contamination with color developer produced purple fog. Historical approaches to that problem that worked included either a long wash after color developer, or a sequence "fix-bleach-fix again". Then came the Fe-EDTA bleach.

Pixophrenic · Jul 11, 2020

GBS said:
@Pixophrenic
B) how realistic/effective is it to regenerate vs. tossing and starting over (I prefer conservation in general, but understand that in some cases, that may be unrealistic)
@Raghu Kuvempunagar's reply seemed to be what I needed to know, as a starting point at least. Link here

I see. Then my humble test may help you.

Mr Bill · Jul 11, 2020

Pixophrenic said:
Would Mr Mowrey please pitch in?

Sadly Ron (Rowland) Mowrey passed away earlier this year.

https://www.photrio.com/forum/threa...rey-aka-pe-photo-engineer-feb-15-2020.173245/

Pixophrenic · Jul 11, 2020

I am sorry, I did not know. This is a great loss for us all.

GBS · Jul 11, 2020

Pixophrenic said:
I see. Then my humble test may help you.

Yes. thank you! That will absolutely be helpful! I've bookmarked this thread

Pixophrenic said:
I am sorry, I did not know. This is a great loss for us all.

I just learned this two days ago. A huge loss for us all.

Does Ferricyanide bleach exhaust? If so when?

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