Oh no! Not another blix thread!

[alanrockwood]

What I would like to see is actual experimental results presented using current blix formulations, run using freshly prepared blix solutions in single shot processing, including both a single 6.5 minute blix step at 104 F and two 6.5 minute blix steps at 104 F using separate blix solutions. The resulting samples should be analyzed for retained silver, bromine, and chlorine. The analysis should be done by neutron activation analysis (NAA) because NAA is an elemental analysis that does not depend on extraction of the target analytes from the sample.

As an alternative to neutron activation analysis the silver content could be analyzed by digesting the sample with concentrated nitric acid and then performing the analysis by inductively coupled plasma mass spectrometry (ICPMS). The iodine content could probably also be analyzed by ICPMS. I'm not sure if ICPMS would work for chlorine or bromine. A third alternative would be to analyze for silver in a digested sample using atomic absorption spectroscopy.

The method above should also be performed on samples of film processed by a conventional C41 process that uses separate bleach and fix solutions. This is for comparative purposes because I can pretty much guarantee that there will be at least a small amount of residual silver in the film regardless of what method is used for bleaching and fixing. Therefore, a comparative analysis is the only one that would be meaningful.

The scheme above would definitively settle the question of how much silver would be left in the film, and if NAA is used it would also answer how much bromine, iodine, and chlorine is left in the film. It would not answer questions about color shifts or longevity.

Optical spectroscopy of processed film could answer questions about color shifts. Unlike the schemes mentioned above, the optical spectroscopy experiments could be performed at home by anyone having a spectrophotometer capable of light transmission measurements, such as the type of spectrophotometers used for color management. A number of photrio members have one of those instruments, including me. Even a colorimeter, film scanner, or flatbed scanner would work well enough for determining relative color shifts. Longevity determinations are another matter altogether.

Realistically, I don't see any prospect of anyone here doing the measurements noted above, except for color the shift measurements. Consequently, as far as current products are concerned, we are reduced to arguing with each other based anecdotes combined with speculation.

 

[Rudeofus]

This scheme would also cost more money that what I'll ever spend on photographic processing, so I guess it will be kind of hard to find volunteers.

 

[trendland]

Wow - it is oft course spekulative! What the real impact of Blix (in your concern "one shot blix - from acuratest formulation" ) will cause to c41 films!
But what is not spekulative is that acuratest c41 workflow with seperate baths are the best method in regard of todays films (wich are designed in regard of actual c41 specification)!
The best method T I L L a competent prove will say the oposite!

Sorry Alan to state : I have some doubts (even spekulative doubts) if that is possible!
But as I mentioned before : To come in the very near I can imagine !

But there is a kind of "indirect prove" : If Blix can do the same job as good AS seperate bleach and fix to 99,6% AND not to 79% Kodak would have stated long time ago : Blix is within tested c41 specification we allow all Kodak Labs to use Blix from this day!

with regards

 

[Photo Engineer]

The test not present in using control strips is granularity. This may be the only definitive test, but there are others that might work such as spectrophotometry.

The only "blixes" I saw that worked were two:

A rehal Ferricyanide/bromide/hypo blix that was one-shot. It went fast. And the second was the FeEDTA/Ammonium Thiocyanate type in our patent US 3706561.

As such, Kodak was unable to get a blix to satisfy their needs and thus the bleach then fix as we now know it was used. To further extend the argument though, Fuji does NOT use a blix either.

PE

 

[trendland]

This scheme would also cost more money that what I'll ever spend on photographic processing, so I guess it will be kind of hard to find volunteers.

Possible it will cost more money than my bonus to a company I worked for - was in 2018!!

with regards

OK - then we can make this test because it wasn't soo much!

 

[alanrockwood]

...As such, Kodak was unable to get a blix to satisfy their needs...
PE

Just to be clear, isn't it true that "Kodak's needs" focused on large scale commercial processing that re-used solutions, and not on small scale processing using single-shot methods? As I see it, the key question for home processors is whether tests were done using freshly prepared blix in single shot mode, especially if the blix time was extended or if blix was applied twice. This mode of operation would not fit into Kodak's business model, not because Kodak would be hesitant about a process that had a large consumable load (think one-shot processing) but because their big commercial processing customers would not accept a single-shot processing model.

As many of you know, I spent my career as a professional chemist. I am not a professional photographic chemist. Actually my PhD work was on a project in "photochemistry" but not "photographic chemistry." Because of my training I am extremely knowledgeable on the topic of chemical kinetics.

Why is this background relevant to the discussion? Because the problem of silver and silver halide removal is, in large measure, a problem in chemical kinetics. (One could also add transport theory to the mix, but that is pretty similar to kinetics from a mathematical perspective.)

It seems to me that a reasonable assumption is that silver and silver halide removal using a fresh blix solution present in large excess would follow a pseudo-first order kinetics model, with different rate constants for the removal of metalic silver and the silver halides. I will grant that first order kinetics might not be a perfect model here, but for the sake of discussion let's assume that it is a reasonable model.

What does this mean? it means that the rate of removal of a component (such as silver) is proportional to the amount of silver left. This implies that the longer a blix process runs less silver (or silver halide) will remain, and that the remaining metalic silver concentration (or silver halide concentration) would have a negative exponential behavior. For example, if 2% of the silver would remain after 6.5 minutes (this is an arbitrary guess) then after 13 minutes only 0.04% of the silver would remain. In other words, if a time of X isn't quite sufficient then a time of 2X is almost certainly sufficient to remove the compound in question down to a negligible level.

Other kinetic models could also be discussed, but the discussion could get rather escoteric. Nevertheless, in virtually any kinetic model one will conclude that if a time of X isn't long enough then some longer (unspecified) term will be long enough to remove an offending compound to a sufficiently low level. This is part of the background of why I am suggesting that running a longer blix step might be a good idea if there there is any question about blix effectiveness.

Note: in the discussion above I am not focusing on other effects, such as stability or color shifts.

 

[alanrockwood]

This scheme would also cost more money that what I'll ever spend on photographic processing...

That's one reason why I say that I don't see that I don't see a prospect for this test being done, especially not these days. In the old days, when film photography was big business, it might have been possible at the companies.

 

[Rudeofus]

Alan, I posted some theory why BLIX may lead to retained silver in this post. This theory, if proven, could also explain, why Ron could make a working BLIX from Ammonium Ferric EDTA and Ammonium Thiocyanate, but not from Ammonium Ferric EDTA and Ammonium Thiosulfate. RA-4 might not suffer from this effect due to its very low silver content and lack of very insoluble silver salts - plus a 0.03 density fluctuation in an RA-4 print hurts much less than the same fluctuation in C-41 negatives.

 

[alanrockwood]

Alan, I posted some theory why BLIX may lead to retained silver in this post. This theory, if proven, could also explain, why Ron could make a working BLIX from Ammonium Ferric EDTA and Ammonium Thiocyanate, but not from Ammonium Ferric EDTA and Ammonium Thiosulfate. RA-4 might not suffer from this effect due to its very low silver content and lack of very insoluble silver salts - plus a 0.03 density fluctuation in an RA-4 print hurts much less than the same fluctuation in C-41 negatives.

Hi Rudeofus. I went to your link. The silver sulfide theory is very interesting. Following up on that idea I found a paper that might be relevant. Here is the link.

https://nvlpubs.nist.gov/nistpubs/jres/64C/jresv64Cn1p65_A1b.pdf

The title of the paper is "Formation of Silver Sulfide In the Photographic Image During Fixation" authored by Chester I. Pope.

I haven't digested the contents of the paper yet.

 

[Photo Engineer]

Imagine that it takes pure 50% NH4FeEDTA to bleach silver metal in a film. And further that it takes pure 50% NH4Hypo to fix the film. If I were to mix those two to make a blix, then the solutions would be each 25% in the active ingredient. I have diluted each component to make my blix. Let us further add the fact that all of the surfaces have adsorbed species which are, among others, Iodide and Phenyl Mercapto Tetrazole. Each of these slow down fixing and bleachiing.

It is hard to get a bleach to get by this. Our original blix, Blix 6, worked well but had a pH of 4.5 and lasted just about 1 day to 1 week depending on formulation. Not good.

Since our original experiments were run in fresh solutions, this was not a test of a continuous process situation where the byproducts built up. Over time, the Iodide and PMT would build up and slow things down even more.

Now, I know that Alan can see the dynamics of the kinetics involved. It (this blix reaction) just won't go quite to completion, and gradually slows down with use. This is not good. We tried Ferricyanide and a fix as a 2 solution process and as a blix. Of course, it worked but as a blix it was short lived and as a 2 solution process sequence, we needed a dev, stop, wash, ferri bleach, wash fix--- etc. The blix here would not keep. And the use of Ferricyanide begs the issue of pollution, something we were trying to minimize in C41.

The Thiocyanate / FeEDTA blix came along too late for C41 and so they are now putting SCN into the current C41 fix. Now, why is that? Well, Kodak went for shorter process times in the current iteration of C41. You see, among the types of C41 films, they vary in Silver content, Iodide content and PMT content over a wide range and that level has gone up to achieve the current speed grain of this family of films. One film may average 2% Iodide, while the faster version may average 10%. One may contain 3 g of silver / sq meter and another might average about 500. These figures are figments of my imagination, but are close.

As I said above, read the patent. It may explain the hours of work in the dark to get the data for the patent. Keith, Gene and I worked very hard on this, believe me.

And, BTW, Ag2S forms readily in film and often can be seen at a level of up to 20 mg / sq meter when retained. After extracting the dyes it forms a dirty grey grainy residue.

PE

 

[mshchem]

What I would like to see is actual experimental results presented using current blix formulations, run using freshly prepared blix solutions in single shot processing, including both a single 6.5 minute blix step at 104 F and two 6.5 minute blix steps at 104 F using separate blix solutions. The resulting samples should be analyzed for retained silver, bromine, and chlorine. The analysis should be done by neutron activation analysis (NAA) because NAA is an elemental analysis that does not depend on extraction of the target analytes from the sample.

As an alternative to neutron activation analysis the silver content could be analyzed by digesting the sample with concentrated nitric acid and then performing the analysis by inductively coupled plasma mass spectrometry (ICPMS). The iodine content could probably also be analyzed by ICPMS. I'm not sure if ICPMS would work for chlorine or bromine. A third alternative would be to analyze for silver in a digested sample using atomic absorption spectroscopy.

The method above should also be performed on samples of film processed by a conventional C41 process that uses separate bleach and fix solutions. This is for comparative purposes because I can pretty much guarantee that there will be at least a small amount of residual silver in the film regardless of what method is used for bleaching and fixing. Therefore, a comparative analysis is the only one that would be meaningful.

The scheme above would definitively settle the question of how much silver would be left in the film, and if NAA is used it would also answer how much bromine, iodine, and chlorine is left in the film. It would not answer questions about color shifts or longevity.

Optical spectroscopy of processed film could answer questions about color shifts. Unlike the schemes mentioned above, the optical spectroscopy experiments could be performed at home by anyone having a spectrophotometer capable of light transmission measurements, such as the type of spectrophotometers used for color management. A number of photrio members have one of those instruments, including me. Even a colorimeter, film scanner, or flatbed scanner would work well enough for determining relative color shifts. Longevity determinations are another matter altogether.

Realistically, I don't see any prospect of anyone here doing the measurements noted above, except for color the shift measurements. Consequently, as far as current products are concerned, we are reduced to arguing with each other based anecdotes combined with speculation.

I spent a good part of my young adult life running AA and other wet chemical analysis . I still place a lot of faith in the works of Kodak Research Labs. In the 1st half ot the 20th century Kodak may not of had the newest whiz bang ICP, but they access to the best equipment and minds in the world. Things that were published were reviewed and confirmed. Everything was challenged for accuracy. Emission spectrometers that took up a room. Xray specs. It must have been amazing.
Real analytical chemists using classic methods of analysis.
As the years progressed Kodak had whatever was needed in terms of the latest and greatest. When Kodak says use bleach and fixer, not blix, that's good enough for me. Sure you can do things differently and get results that are acceptable. Science is difficult for some to tolerate. But facts are facts.

 

[PittP]

When Kodak says use bleach and fixer, not blix, that's good enough for me.

Well, Tetenal (and others) claim their Blix is at least as good. Fuji at some time, too, had blixes for both c41 and e6.
The OP's question was on a rather theoretical level, in brief: Can a blix actually work reliably well.
The answers I get so far: Paper (RA4) - yes. Film (c41 and e6) - rather no. (with possible high variations between various products). Reuse of blix in films is bad, a 2-step blix might improve the situation a bit...
Now, Tetenal at least proposed 2 reuses. (From practical experience, I don't trust but 1 reuse with half the number of films per solution.)
On a practical level, the blix has further issues:

• The bleach is an expensive component, which alone could be reused many times, and has good keeping qualities. Thus, wasting its capacity in a blix is a serious waste of money, and creates extra environmentally harmful waste. Even at the hobbyist level, this is not desirable at all.
• For the fixer part similar considerations hold, the concentrates have (very) limited shelf life, in the blix-mix the fixing capacities of the used chemicals are by far less than in a separate fix. Thus again, more uncertainty in the process (is the fix in the blix still good?), more cost, and more waste.

Thus, even if the blix could theoretically work (somehow), in practical use it must be avoided. For Film at least. I can't judge the situation in ra4, may be similar, though.

 

[mshchem]

Well, Tetenal (and others) claim their Blix is at least as good. Fuji at some time, too, had blixes for both c41 and e6.
The OP's question was on a rather theoretical level, in brief: Can a blix actually work reliably well.
The answers I get so far: Paper (RA4) - yes. Film (c41 and e6) - rather no. (with possible high variations between various products). Reuse of blix in films is bad, a 2-step blix might imrpove the situation a bit...
Now, Tetenal at least proposed 2 reuses.
On a practical level, the blix has further issues:
*The bleach is an expensive component, which alone could be reused many times. Thus, wasting its capacity in a blix is a serious waste of money, and creates extra environmentally harmful waste. Even at the hobbyist level, this is not desiarable at all.

Tetenal says you can reuse 3 bath E6 until you get results that are no longer acceptable. It needs to be clear that Tetenal makes the blix film kits for the amateur market . Tetenal makes standard separate bleach and fixer chemistry for commercial labs. There's no real question to people that understand the science. I don't pretend to understand, but I believe people that do. PE has been repeating this for ever, I believe he actually knows what he's talking about. I also think Eastman Kodak and Fujifilm AND Tetenal know too.

 

[mshchem]

That's one reason why I say that I don't see that I don't see a prospect for this test being done, especially not these days. In the old days, when film photography was big business, it might have been possible at the companies.

If film was still the business it was in the old days we would probably be on C-184 by now, finer grain than technical pan film, ASA 10 TO 6400 on the fly and auto color temperature correction . One solution at 55 to 105 F for 2 minutes that made a darn fine pale ale when chilled.

 

[Rudeofus]

Imagine that it takes pure 50% NH4FeEDTA to bleach silver metal in a film. And further that it takes pure 50% NH4Hypo to fix the film. If I were to mix those two to make a blix, then the solutions would be each 25% in the active ingredient.

This by itself would not at all be a problem, since typical bleach and fixer come as 40-60% concentrates, while their working solutions contain close to 10% of the active ingredient. The bigger issue is, that you can't add 10% random stuff to fixer and expect it to perform as well as pure fixer. If you want to see this for yourself, mix increasing amounts of Ammonium Acetate into rapid fixer and see what it does to clearing speed, despite the fact that Silver Acetate is very soluble and that Ammonia is even a silver solvent.

So the problem does not arise from dilution of Ammonium Thiosulfate, but from the fact that lots of extra stuff is added to it. There are reasons to believe, that the same problem affects Ammonium Ferric EDTA, where extra ions weaken its bleaching power.

But while all that would slow down BLIX, it would not prevent it from working. My theory, backed up by the article Alan dug up, would actually explain why Silver Sulfide would remain in the emulsion regardless of how fresh the bleach is. Any things which further slow down BLIX, such as iodide, PMT, silver load, .... would expose more silver to the Thiosulfate and would therefore allow more silver to be converted to Silver Sulfide. It sounds crazy, but the reason thiosulfate works as fixer is that we can't normally see the large amounts of Silver Sulfide it creates.

PS: The article linked to by Alan mentions Potassium Iodide as possible ingredient to rapid fixer to avoid the formation of Silver Sulfide. This would not work in BLIXes, since the bleach component would oxidize iodide at once, rendering it ineffective.

 

[trendland]

Well, Tetenal (and others) claim their Blix is at least as good. Fuji at some time, too, had blixes for both c41 and e6.
The OP's question was on a rather theoretical level, in brief: Can a blix actually work reliably well.
The answers I get so far: Paper (RA4) - yes. Film (c41 and e6) - rather no. (with possible high variations between various products). Reuse of blix in films is bad, a 2-step blix might improve the situation a bit...
Now, Tetenal at least proposed 2 reuses. (From practical experience, I don't trust but 1 reuse with half the number of films per solution.)
On a practical level, the blix has further issues:

• The bleach is an expensive component, which alone could be reused many times, and has good keeping qualities. Thus, wasting its capacity in a blix is a serious waste of money, and creates extra environmentally harmful waste. Even at the hobbyist level, this is not desirable at all.
• For the fixer part similar considerations hold, the concentrates have (very) limited shelf life, in the blix-mix the fixing capacities of the used chemicals are by far less than in a separate fix. Thus again, more uncertainty in the process (is the fix in the blix still good?), more cost, and more waste.

Thus, even if the blix could theoretically work (somehow), in practical use it must be avoided. For Film at least. I can't judge the situation in ra4, may be similar, though.

.......hmmm - so what we are talking about???

What is blix ? Blix is an invention of kit manufacturers! A real big coup!
They told people : " Folks - now you can save much time - here is our 2bath process !"
But folks if it is realy such complicate to develope 3bath???

The environmental issue may not to be seen by some! (mee to - but I thought about) but from
issue in regard of saving money it is just stupit to use blix!
If at last the quality isn't the same - it is "just perfect"!

- not realy more easy (what is such complicate with bleach and fix + additional water bath)
- more expensive
- less quality. (the issue of long term stability is bejond dispute!)

So what the hell has moved the manufacturers? The possible answer should be :
The mass want it - hmm!

with regards

 

[trendland]

If film was still the business it was in the old days we would probably be on C-184 by now, finer grain than technical pan film, ASA 10 TO 6400 on the fly and auto color temperature correction . One solution at 55 to 105 F for 2 minutes that made a darn fine pale ale when chilled.

Form my point ISO 3200 (for color film) is a physical limit ! No technique advance is able to brake it!
The smal grain of technical pan film seams to be possible with color film but this just at ISO 10 !

with regards

 

[Photo Engineer]

Rudi, think about what you just wrote! A bleach could be made from nearly pure NH4FeEDTA, but a blix would be diluted nearly 50%! Any blix is less concentrated than a comparable bleach might be. And, addition of ions can speed up a bleach or blix. Ammonium bleaches and blixes are faster than Sodium bleaches or blixes. This is due to the auxiliary solvent effects of the Ammonium ion itself.

I don't believe that Iodide is oxidized to Iodate in a blix and perhaps not even in a strong bleach. Iodide is found in bleaches and blixes as Iodide. Sulfide forms all the time in film during bleaching, blixing and fixing.

PE

 

[Rudeofus]

Rudi, think about what you just wrote! A bleach could be made from nearly pure NH4FeEDTA, but a blix would be diluted nearly 50%! Any blix is less concentrated than a comparable bleach might be.

Nobody makes bleaches from 100% or 50% Ammonium Ferric EDTA, AFAIK 10% is common in Kodak's and Fuji's E6 bleaches! You could use commonly available concentrates to make a BLIX with 25% Ammonium Ferric EDTA and 30% Ammonium Thiosulfate. This would be more than twice as strong as comparable bleach and three times as strong as typical fixer.

Dilution is not the issue, high ionic strength is, even if you formulate a BLIX from 10% Ammonium Ferric EDTA and 10% Ammonium Thiosulfate.

I don't believe that Iodide is oxidized to Iodate in a blix and perhaps not even in a strong bleach. Iodide is found in bleaches and blixes as Iodide.

If aerial oxygen quantitatively converts iodide to iodate in a matter of weeks, then a bleach that's frequently aerated should do this even faster, at least Mr. Fenton would suggest this.

 

[trendland]

Rudi, think about what you just wrote! A bleach could be made from nearly pure NH4FeEDTA, but a blix would be diluted nearly 50%! Any blix is less concentrated than a comparable bleach might be. And, addition of ions can speed up a bleach or blix. Ammonium bleaches and blixes are faster than Sodium bleaches or blixes. This is due to the auxiliary solvent effects of the Ammonium ion itself.

I don't believe that Iodide is oxidized to Iodate in a blix and perhaps not even in a strong bleach. Iodide is found in bleaches and blixes as Iodide. Sulfide forms all the time in film during bleaching, blixing and fixing.

PE

....still understanding (where is the argument..?) because why a blix is mixed out of the half fixing solution and a ~ half bleaching solution the bleach can have a max. concentration of 50%
WITHIN THE TOTAL BLIX SOLUTION!

with regards

 

[trendland]

Nobody makes bleaches from 100% or 50% Ammonium Ferric EDTA, AFAIK 10% is common in Kodak's and Fuji's E6 bleaches! You could use commonly available concentrates to make a BLIX with 25% Ammonium Ferric EDTA and 30% Ammonium Thiosulfate. This would be more than twice as strong as comparable bleach and three times as strong as typical fixer.

Dilution is not the issue, high ionic strength is, even if you formulate a BLIX from 10% Ammonium Ferric EDTA and 10% Ammonium Thiosulfate.

If aerial oxygen quantitatively converts iodide to iodate in a matter of weeks, then a bleach that's frequently aerated should do this even faster, at least Mr. Fenton would suggest this.

....are comparable bleach and fixing baths indeed such less concentrated like you stated rudeofus?
(Sorry I have it not in mind jet and I have no formulation on the hand - but one of you possible made a failure here?)

with regards

 

[Photo Engineer]

I said "could be made". This is used as an example to make the point that a blix is diluted more than a bleach when making it up to working strength.

I also said that the bleach or blix was probably not oxidizing Iodide to Iodate. It is the Oxygen in the air or being used to regenerate the blix or bleach. A bottle of KI solution kept on the shelf will gradually turn into Periodate solution. At EK we made up fresh every week or so.

PE

 

[trendland]

I said "could be made". This is used as an example to make the point that a blix is diluted more than a bleach when making it up to working strength.

I also said that the bleach or blix was probably not oxidizing Iodide to Iodate. It is the Oxygen in the air or being used to regenerate the blix or bleach. A bottle of KI solution kept on the shelf will gradually turn into Periodate solution. At EK we made up fresh every week or so.

PE

so it is also in concern of interaction of chems! PE let me state I am on your side in regard of Blix!
It is comming from manufacturers of developing kits who stated : we don't care any longer about Kodaks c41 specification here is out New soup - later they stated : it is working exact the same as
Kodak specification - next will be that they will state : it is better than c41 from Kodak specification!
Hart to belive ?

with regards

 

[Rudeofus]

I said "could be made". This is used as an example to make the point that a blix is diluted more than a bleach when making it up to working strength.

I must be denser than a neutron star today, simply don't get it. If one wanted to make a working BLIX, 10% Ammonium Ferric EDTA and 10% Ammonium Thiosulfate plus trace amounts of bleach accelerator plus some acid for pH adjustment is all you need. This can be trivially made from available concentrates, and all liquid BLIX kits do it this way. If kit manufacturers wanted to make that more concentrated, even a BLIX with 25% Ammonium Ferric EDTA and 30% Ammonium Thiosulfate is feasible - and pointless! Yes, you could make a bleach with 50% Ammonium Ferric EDTA and a fixer with 60% Ammonium Thiosulfate, but nobody wants or needs that high a concentration!

 

[trendland]

I must be denser than a neutron star today, simply don't get it. If one wanted to make a working BLIX, 10% Ammonium Ferric EDTA and 10% Ammonium Thiosulfate plus trace amounts of bleach accelerator plus some acid for pH adjustment is all you need. This can be trivially made from available concentrates, and all liquid BLIX kits do it this way. If kit manufacturers wanted to make that more concentrated, even a BLIX with 25% Ammonium Ferric EDTA and 30% Ammonium Thiosulfate is feasible - and pointless! Yes, you could make a bleach with 50% Ammonium Ferric EDTA and a fixer with 60% Ammonium Thiosulfate, but nobody wants or needs that high a concentration!

That would cause a blix in a black whole once a day - and blix isn't working any longer -
remember the influence of dark matter to your blix solution then!!

with regards

Neutron star density - that is not comming from Tetenal I gues!