Mysterious Substance in Part C ???

Rudeofus · May 11, 2019

roundcloud said:
1. Kodak C41b C,as the title.

Have you ever created a replacement for Kodak C41b C from CD-4 and Sodium Metabisulfite and checked, whether it behaves the same way?

roundcloud said:
2. Tetenal C41 Developer Part 3 , its color will darken (yellowing) over time. I think it must have anti-fogging effect. But traditional formula C41 doesn't have this. (Part 3 contains - K2CO3, DTPA - Na5)

There is no standard for calling C-41 CD parts, therefore whatever Kodak calls part C may be Tetenal's part 1 or 2. Check the MSDS, while it doesn't have to give exact composition, it should be easy to differentiate between the three parts. Typically one part contains CD-4 + metabisulfite/Sulfur Dioxide, another part containst HAS or derivatives thereof, and the third part contains the rest (alkali, restrainers, sequestering agents)

roundcloud said:
3. Tetenl Blix has excellent "stop function" even exceeding C41B bleach, but its PH value is 6.8. What's in it?

Tetenal's BLIX contains Ammonium Ferric EDTA, Ammonium Thiosulfate, a bleach accelerator and acetic acid to get the pH down to 6.5. Since Ammonium Thiosulfate is a speedy fixer, there's a good chance that it removes silver halide before developer can act.

I would, however, question the term "excellent stop function" applied to Tetenal's BLIX, it has been reported many times over, that especially medium format C-41 film gets yellow splotches if one goes directly from C-41 CD to used BLIX. These yellow blotches do not appear if a stop&rinse is applied between CD and BLIX.

roundcloud · May 12, 2019

Photo Engineer said:
Well, this will take some time to think about. It seems that each company has their own chemistry. They did give considerably different results in terms of speed, grain, color and sharpness. This was shown in a magazine a few years ago. I did save it but cannot find it now. It might help a bit.

I'll do my best but it will take time.

PE

thanks！！
Now my only research finding——the blix，2g ethylenethiourea/1L can make the traditional bleaching solution have 4times speed increase.CAS No: 96-45-7

roundcloud · May 12, 2019

Have you ever created a replacement for Kodak C41b C from CD-4 and Sodium Metabisulfite and checked, whether it behaves the same way?
——That's a good idea.But I don't know the content of CD4 in C41B. and I have been replaced part A&B with K2CO3,NaBr，NaHCO3，highlight and midlight turns to Magenta.

There is no standard for calling C-41 CD parts, therefore whatever Kodak calls part C may be Tetenal's part 1 or 2. Check the MSDS, while it doesn't have to give exact composition, it should be easy to differentiate between the three parts. Typically one part contains CD-4 + metabisulfite/Sulfur Dioxide, another part containst HAS or derivatives thereof, and the third part contains the rest (alkali, restrainers, sequestering agents)

Tetenal's BLIX contains Ammonium Ferric EDTA, Ammonium Thiosulfate, a bleach accelerator and acetic acid to get the pH down to 6.5. Since Ammonium Thiosulfate is a speedy fixer, there's a good chance that it removes silver halide before developer can act.

I would, however, question the term "excellent stop function" applied to Tetenal's BLIX, it has been reported many times over, that especially medium format C-41 film gets yellow splotches if one goes directly from C-41 CD to used BLIX. These yellow blotches do not appear if a stop&rinse is applied between CD and BLIX.
——may be sulphur precipitation？ caused by developer solution.
BTW，any stop will cause highlight yellowing，highlight's gloss will be lost.
I used tetenal to process 5,000 films（135 and 120） and never had a problem.

Photo Engineer · May 12, 2019

Your results look very good but a bit low in contrast. No crossover. IDK what your process was, but I suggest that at 100F (38.XC), you might go about 15" longer in the developer.

As for Thioureas in general, they speed up all fixes and blixes but are powerful fogging agents so don't let them escape in the darkroom. We covered many of these and some others as well in our Blix patent for Kodak (Mowrey, Stephen and Wolfarth).

PE

fdonadio · May 12, 2019

roundcloud said:
But I don't know the content of CD4 in C41B.

Does anyone really know?

Photo Engineer · May 12, 2019

It ends up at about 5 g/l in the final working developer, but each mfgr. uses a different mix and so it is hard to tell.

You can work backwards.

PE

fdonadio · May 13, 2019

Photo Engineer said:
You can work backwards.

Well... in my case, I have Kodak’s C41-RA (LORR) and the developer’s part C is the first to go bad.

I do have some CD4 in solid form and can prepare that solution easily.

Now I just need to know if the starter reacts with CD4 in the replenisher when mixing the tank solution. If it does, it will be hard for me to calculate, as the reaction might be more complex than my chemistry skills would allow me to understand.

koraks · May 13, 2019

As far as I'm aware the starter is a balanced mixture of bromides and iodides to stimulate these halides from soaking out of processed film. If so, no reaction is to be expected between the starter and the developer itself.

trendland · May 13, 2019

koraks said:
As far as I'm aware the starter is a balanced mixture of bromides and iodides to stimulate these halides from soaking out of processed film. If so, no reaction is to be expected between the starter and the developer itself.

That's right BTW! Starter is not doing activation of the developer = without starter the developer isn't working insn't the mechanism!!! It is not like to start the engine!
But it is (in parts) an aditive what you will not need later - at the point development proceeds!

with regards

PS : Best Avatar now!!!!

roundcloud · May 13, 2019

Photo Engineer said:
Your results look very good but a bit low in contrast. No crossover. IDK what your process was, but I suggest that at 100F (38.XC), you might go about 15" longer in the developer.

As for Thioureas in general, they speed up all fixes and blixes but are powerful fogging agents so don't let them escape in the darkroom. We covered many of these and some others as well in our Blix patent for Kodak (Mowrey, Stephen and Wolfarth).

PE

38℃，3:15，accommodat the tolerance of pour in and out together.BTW，15 seconds development time almost can't change the color's impression，only change the tone.
Thioureas ，the slight fog does happen，even in the darkroom all time.

roundcloud · May 13, 2019

Photo Engineer said:
It ends up at about 5 g/l in the final working developer, but each mfgr. uses a different mix and so it is hard to tell.

You can work backwards.

PE

At present I use 4.6g CD-4@1L ，I'll try 5g sometime，but Na2SO3/NaBr/PH have to change accordingly

roundcloud · May 13, 2019

koraks said:
As far as I'm aware the starter is a balanced mixture of bromides and iodides to stimulate these halides from soaking out of processed film. If so, no reaction is to be expected between the starter and the developer itself.

iodides may lead highlight to dull yellow，I'm sure C41B does not contain it.

Photo Engineer · May 13, 2019

roundcloud said:
At present I use 4.6g CD-4@1L ，I'll try 5g sometime，but Na2SO3/NaBr/PH have to change accordingly

Yes, of course, but I seem to remember that 5 g/l was near the aim.

PE

koraks · May 14, 2019

roundcloud said:
iodides may lead highlight to dull yellow，I'm sure C41B does not contain it.

I found a C41 formula that Photo Engineer posted to Photo.net I think, years ago. I'm pretty sure it included a tiny amount of KI.

Rudeofus · May 14, 2019

Yes, there is a balance of bromide and iodide in most color processing bathes (ECN-2 and ECP-2 the most notable exceptions), and the ratio of bromide to iodide adjusts color balance.

@roundcloud : did you experience these "dull yellow highlights" with the correct (according to formula) ratio of bromide to iodide, or did you experiment with iodide alone ?

Photo Engineer · May 14, 2019

koraks said:
I found a C41 formula that Photo Engineer posted to Photo.net I think, years ago. I'm pretty sure it included a tiny amount of KI.

AFAIK, I have posted no authentic C41 formulas anywhere, but have posted approximations of some from patents. When I do, I qualify that information.

PE

koraks · May 14, 2019

That's right, you explicitly mentioned it was a close approximation. Neither you nor I have said it was an official formula.

Rudeofus · May 15, 2019

These formulas here were at least claimed to be in practical use at KRL.

roundcloud · May 15, 2019

Rudeofus said:
Yes, there is a balance of bromide and iodide in most color processing bathes (ECN-2 and ECP-2 the most notable exceptions), and the ratio of bromide to iodide adjusts color balance.

@roundcloud : did you experience these "dull yellow highlights" with the correct (according to formula) ratio of bromide to iodide, or did you experiment with iodide alone ?

Potassium iodide is generally 1.5-2 mg，just I have a very high demand for color，I'm sick............

Rudeofus · May 15, 2019

The iodide content you specified sounds a bit high. Ron Mowrey's formulas state 1.2 mg/l, so does the formula published in US6649331 (7.229 * 106 * 166.0028). Stefan Lange recommends 1.4 mg/l. Grant Haist's C-42 formula is the only one I know to use 2.0 mg/l.

koraks · May 15, 2019

The minute amount of iodide applied in the developer always made me wonder how it compares to iodide being liberated from the film during processing, particularly when using eg 150ml of developer for a roll of 36 exp 135 in a Jobo 1510. I never really thought deeply about it, I have to admit. Any comments on this?

RPC · May 15, 2019

Iodide, like bromide is a restrainer, albeit a very powerful one and a very small, precise amount must be present in the developer to control the image optimally. PE would have all the details but I believe it controls interimage effects, sharpness and grain. I would think any iodide in and from the film and present in the developer formula must be very delicately balanced for optimum image quality.

Photo Engineer · May 15, 2019

The Iodide in the developer affects the emulsions from the top down, and the Iodide released is a function of imaging and image position. DIR fragments are released basically from the bottom up but it is more complex than that. DIR fragments are far stronger than Iodide in effect. This is a complex dance that leads to sharpening of the image, balancing of the color and lowering the fog while also balancing the developer if it is to be used with replenishment.

By measurement, if you did 3 rolls in a row vs 3 rolls at once, you would see a difference in many attributes in the ones done in a row one at a time. This would be a progressive effect.

It is very very complex to explain. We used a complex series of exposures to measure color, grain and sharpness just for starters.

PE

koraks · May 16, 2019

Thank you for adding this information @Photo Engineer. Intuitively I see the mechanism and I also recognize that it's quite complex. I also recognize from experience the roll-to-roll difference in eg acutance with small developer volumes.

Photo Engineer · May 16, 2019

I'm surprised that you see the difference in that type of processing, especially without equipment to run the tests.

PE

Mysterious Substance in Part C ???

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