Kodak fogging redeveloper - dithionite

[DeletedAcct1]

Hi all,
the following is the Kodak FD70 formula:

First Prepare:
Kodak FD-70a Part B Stock Solution
to
Warm Water ( ~50ºC ) CAS # 7732-18-5 750 ml


add and dissolve
Sodium Metaborate CAS # 16800-11-6 15.0 grams
4,6-Dihydroxy-2-Mercaptopyrimidine CAS # 504-17-6 0.5 grams


then add
Cold Water ( ~20ºC ) CAS # 7732-18-5 to make 1,000 ml


Second Prepare:
Immediately, Not to exceed 2 hours, of use
Kodak FD-70a Working solution ( 500 ml )
to
Kodak FD-70a Part B Stock Solution( ~20ºC ) 500 ml


add and dissolve
Kodak FD-70a Part A
Sodium Dithionite CAS # 7775-14-6 3.0 grams

Questions:
1) what the 4,6-Dihydroxy-2-Mercaptopyrimidine is for? (2-thiobarbituric acid)
2) what if the 2-thiobarbituric acid is omitted?

 

[Raghu Kuvempunagar]

FD-70 has thiobarbituric acid and FD-72 has cysteine hydrochloride. Jerry Koch was of the opinion that these two are there in the second developer formulas for clearing highlights. I've used neither as they are not easily available in the local chemicals shop. For paper reversal I use a little bit of thiosulphate with dithionite and it does give better highlights and a warm tone.

 

[DeletedAcct1]

FD-70 has thiobarbituric acid and FD-72 has cysteine hydrochloride. Jerry Koch was of the opinion that these two are there in the second developer formulas for clearing highlights. I've used neither as they are not easily available in the local chemicals shop. For paper reversal I use a little bit of thiosulphate with dithionite and it does give better highlights and a warm tone.

So do you suggest to use thiosulphate instead of the exotic chemicals?
It does make sense as thiosulphate can be an S donor as thiobarbituric acid and cysteine are

 

[Rudeofus]

Cysteine is sold in health&food supplement stores, so it should be easily available. BTW raw Cysteine is a very poor silver solvent, but when in alkaline solution (such as a developer) it actually works quite well as fixer/solvent. I don't know much about Thiobarbituric Acid and its derivatives, but I would generally not look too intensively for anything with the word "barbituric" in its name.

I still haven't figured out the exact reason, but Thiocyanate and DTOD are much preferred in photographic developers over Thiosulfate. Both are easy to obtain from Fototechnik Suvatlar, although DTOD may not be shown on his price lists.

 

[Raghu Kuvempunagar]

So do you suggest to use thiosulphate instead of the exotic chemicals?
It does make sense as thiosulphate can be an S donor as thiobarbituric acid and cysteine are

Haist mentions in Volume 2 that thiobarbituric acid can "render undevelopable certain layers of a multilayer film" and it can "slow down the development of upper layers". If this is how it is clearing the highlights, i.e.by rendering some layer of the film undevelopable, then thiosulphate can't be used as its replacement.

I still haven't figured out the exact reason, but Thiocyanate and DTOD are much preferred in photographic developers over Thiosulfate.

I've not seen any formula that uses Thiocyanate or DTOD in second developer of B&W reversal. Can you provide some references?

 

[Raghu Kuvempunagar]

Haist mentions in Volume 2 that thiobarbituric acid can "render undevelopable certain layers of a multilayer film" and it can "slow down the development of upper layers". If this is how it is clearing the highlights, i.e.by rendering some layer of the film undevelopable, then thiosulphate can't be used as its replacement.

Also note that thiobarbituric acid is a stabilizing agent. When used with dithionite this might mean that fixing after second development is not needed. However, the reversal process that employs FD-70 does recommend fixing.

 

[Rudeofus]

Also note that thiobarbituric acid is a stabilizing agent. When used with dithionite this might mean that fixing after second development is not needed. However, the reversal process that employs FD-70 does recommend fixing.

If you refer to pages 216f of Haist's volume 2, then stabilization can mean different things. There is also Thiourea in this list, which is a powerful silver solvent. There is also Cystein in this list, which is a good fixer at high pH.

About solvent in second developer: you are right, I could not find a classic second developer for black&white reversal with strong solvent. Sole exception would be FD-72 with its alkaline Cysteine. However, E-4 and E-6 both use strong solvents in their color developers, and there is no credible reason why such a thing would not work for b&w reversal. As long as the first developer is sufficiently foggy, there should not be a problem with "clearing highlights" regardless of second developer.

 

[Raghu Kuvempunagar]

However, E-4 and E-6 both use strong solvents in their color developers, .

Which of these uses either thiocyanate or DTOD in the second developer?

As long as the first developer is sufficiently foggy, there should not be a problem with "clearing highlights" regardless of second developer.

If that's the case then why did Kodak include cysteine hydrochloride in the second developer when the first developer, D-67, has thiocyanate in it?

 

[removed account4]

I know you are in Rome Alessandro can you get your hands on a rust remover sold at local American hardware store called rust out, when I have done peroxide reversals I sometimes use that, it is fogging redeveloper ( with thiosulfate in it so it is a monobath develop + fix ). if you can get your hands on rust out you won't have to compound your own version...

 

[Donald Qualls]

That rust remover (for laundry) is called "Iron Out". It's (as I recall) a 3% solution of sodium dithionite (though as a laundry product, it probably also includes perfumes, dyes, surfactants, and other stuff). You'd need to make an alkaline solution of this, I think, but I recall Photo Engineer writing that it ought to work directly as a fogging developer for B&W reversal, just as thiourea toner will.

 

[grainyvision]

That rust remover (for laundry) is called "Iron Out". It's (as I recall) a 3% solution of sodium dithionite (though as a laundry product, it probably also includes perfumes, dyes, surfactants, and other stuff). You'd need to make an alkaline solution of this, I think, but I recall Photo Engineer writing that it ought to work directly as a fogging developer for B&W reversal, just as thiourea toner will.

I've used iron out for a few purposes. It's uhh... difficult. Even as a powder it's very unstable so you never know the exact composition you're working with. There's several patents and research papers about using exotic solvents to preserve dithionite in solution, but the best case is keeping it 80% alive over a period of 3 days when kept below 0C. It's incredibly difficult to use with any amount of precision. Dithionite is also hard to source due to how volatile it is. One note for Iron Out specifically is that putting it in acid will form hydrogen sulfide (rotten egg smell), which will fog any materials near it. Dithionite is not greatly active in a neutral solution. It will act as a non-developing fogging agent but be fairly slow in its action. With alkali added it will act as an extremely active fogging developer, developing to completion very fast. With alkali added though, it will be even less stable and maximum shelf life is something closer to 1 hour before 99% dead. It is soluble in triethanolamine which seems to be the best stabilizing solvent. If kept cold (use a little bit of water to reduce freezing point of TEA) then it'll retain quite a bit of activity over several weeks. So the best course of action is to use 200-400% more dithionite than should be needed to account for the activity level to decrease by 50% over 1 week

 

[Donald Qualls]

So the best course of action is to use 200-400% more dithionite than should be needed to account for the activity level to decrease by 50% over 1 week

Or mix from powder immediately before starting to process. For B&W reversal (which is where I'd planned to use it), an extremely active fogging developer is very acceptable, even desirable. Hydrogen sulfide, OTOH, won't just fog all materials nearby, it'll fog you -- it's more toxic than hydrogen cyanide, and you completely lose your ability to smell it just below significantly toxic concentrations.

I just looked at the (unopened) container of Iron Out I have on hand -- it apparently contains sodium bisulfite as well, which seems likely to ensure it's acidic when mixed with water. No wonder they have a warning about skin contact and use by people with breathing disorders.

 

[DeletedAcct1]

So to recap, dithionite is the most convenient reducing agent but it needs to be in alkaline solution. Should sodium carbonate suffice and if yes, in what amount?
I've sourced the dithionite here https://www.kremer-pigmente.com/it/...i/sostanza-inorganica/2167/ditionito-di-sodio, what amout is required to be working as a foggant?

 

[grainyvision]

Or mix from powder immediately before starting to process. For B&W reversal (which is where I'd planned to use it), an extremely active fogging developer is very acceptable, even desirable. Hydrogen sulfide, OTOH, won't just fog all materials nearby, it'll fog you -- it's more toxic than hydrogen cyanide, and you completely lose your ability to smell it just below significantly toxic concentrations.

I just looked at the (unopened) container of Iron Out I have on hand -- it apparently contains sodium bisulfite as well, which seems likely to ensure it's acidic when mixed with water. No wonder they have a warning about skin contact and use by people with breathing disorders.

to be fair, sulfide is extremely smelly. It's believed to be one of the smells that humans are most sensitive to. Iirc we can smell it down to a few parts per billion. So it doesn't take much to release what seems like a massive amount. The exact thing I did to release it was adding about 20ml of 5% oxalic acid to a tray of water with some iron out dissolved in it. The solution began to bubble, I smelled sulfide, and evacuated outdoors leaving my dark room open. When the smell was less oppressive (keeping in mind that I'd lose sensitivity to it) I poured it down the drain and left water rubbing for several minutes and ran some fans to clear out the remaining smell. It didn't fog any of my paper or film in the room so I assume the release wasn't actually very bad, but still scary considering it was an unexpected reaction and how dangerous hydrogen sulfide can be

 

[removed account4]

look at the posts towards the end by donF in this post >>>https://www.photrio.com/forum/threads/reversal-print-processing-video-new-approach.153447/
he uses rust out by the teaspoon as a 2nd developer ( fogging developer and fix ) step to make reversal images. he does not have troubles with contaminants or anything bad happening to his images. personally I'd use something ready made like rust out ( or whatever is similar in Rome ) instead of messing around with crazy chemistry to get something similar but marketed by Kodak. hydrogen sulfide, is scary stuff..

 

[DeletedAcct1]

look at the posts towards the end by donF in this post >>>https://www.photrio.com/forum/threads/reversal-print-processing-video-new-approach.153447/
he uses rust out by the teaspoon as a 2nd developer ( fogging developer and fix ) step to make reversal images. he does not have troubles with contaminants or anything bad happening to his images. personally I'd use something ready made like rust out ( or whatever is similar in Rome ) instead of messing around with crazy chemistry to get something similar but marketed by Kodak. hydrogen sulfide, is scary stuff..

In Rome IronOut isn't available nor an equivalent.
If it's too much of a hassle, I'm out.

 

[Raghu Kuvempunagar]

In Rome IronOut isn't available nor an equivalent.
If it's too much of a hassle, I'm out.

5g dithionite + 5g sodium carbonate in 500ml RO water works fine for me as second developer for one roll of 35mm film. YMMV.

As far as its use in reversal processing is concerned, dithionite is pretty straightforward to use. I've never tried to add acid to it or tried to store the solution for hours or days. I mix it just before use and use the solution only once. Before putting the the dithionite solution to use, I immerse a small piece of exposed film, say the leader, in it and check if it blackens in 2-3 minutes. It's like doing a clip test before using any developer.

And btw dithionite or iron out doesn't do fixing as claimed by one of the posters. Nor does it contain thiosulphate. You can check the datasheet and confirm. A fixing step is recommended to remove those hard-to-reduce halides that might still be in the film after second development.

Dithionite is also called Hydrosulphite and is used in fabric art for dyeing and discharging. You may be able to find it in stores that cater to dye based art. For example, in USA it's available as a chemical for use in indigo dyeing: https://www.dharmatrading.com/chemicals/jacquard_sodium_hydrosulfite.html

 

[DeletedAcct1]

Dithionite is also called Hydrosulphite and is used in fabric art for dyeing and discharging. You may be able to find it in stores that cater to dye based art.

5g dithionite + 5g sodium carbonate in 500ml RO water works fine. Mix it just before use.

Thanks. Have you tried this formula?

 

[Raghu Kuvempunagar]

Thanks. Have you tried this formula?

Yes, of course.

 

[Rudeofus]

Which of these uses either thiocyanate or DTOD in the second developer

Someone posted Fuji's E-6 recipes here a while ago, and there is 1 g/l DTOD in the color developer. There is also a Kodak teaching patent for making an E-6 5 liter kit, and this color developer also uses DTOD. Kodak's E-4 formula require Ethylene Diamine (see Grant Haist vol 2 p 567). In the same fashion Stefan Lange's Chromebrew uses alternatively Thiocyanate or Ethylenediamine in its color developer. You may have been right about B&W reversal second developers, there really are no formulas out there with strong solvent, but in E-4/E-6 this is established practice.

While we are at it, Agfa AP-41 process also uses Ethylene Diamine Sulfate in its color developer. This really seems to be established practice in color reversal processing, and I have no idea, why this was never used in public B&W reversal formulas. We'll see what DR-5 will publish in a few months.

If that's the case then why did Kodak include cysteine hydrochloride in the second developer when the first developer, D-67, has thiocyanate in it?

I have no real idea, why Kodak put either Thiobarbituric Acid or Cysteine into their reversal developers. Since Cysteine appears to be non-toxic and moderately cheap, it is up to anybody to compare the results from Dithionite alone with results from Dithionite plus Cysteine. Once we see the diifference (or lack thereof), we can start answering this question.

@Alessandro Serrao : Dithionite should be very cheap and very easy to obtain. There's got to be a chemical store somewhere in Rome. Raghu's recipe probably works fine.

 

[Raghu Kuvempunagar]

You may have been right about B&W reversal second developers, there really are no formulas out there with strong solvent, but in E-4/E-6 this is established practice.

While we are at it, Agfa AP-41 process also uses Ethylene Diamine Sulfate in its color developer. This really seems to be established practice in color reversal processing, and I have no idea, why this was never used in public B&W reversal formulas.

Every component in a well-designed formula is there for a good technical reason. What is the reason for using strong solvents in the color developer of E-4/E-6 processes? PE has stated that Ethylenediamine is meant to promote dye formation and give better grain in color slide film. How's this even relevant to B&W reversal?

 

[DeletedAcct1]

Someone posted Fuji's E-6 recipes here a while ago, and there is 1 g/l DTOD in the color developer. There is also a Kodak teaching patent for making an E-6 5 liter kit, and this color developer also uses DTOD. Kodak's E-4 formula require Ethylene Diamine (see Grant Haist vol 2 p 567). In the same fashion Stefan Lange's Chromebrew uses alternatively Thiocyanate or Ethylenediamine in its color developer. You may have been right about B&W reversal second developers, there really are no formulas out there with strong solvent, but in E-4/E-6 this is established practice.

While we are at it, Agfa AP-41 process also uses Ethylene Diamine Sulfate in its color developer. This really seems to be established practice in color reversal processing, and I have no idea, why this was never used in public B&W reversal formulas. We'll see what DR-5 will publish in a few months.

I have no real idea, why Kodak put either Thiobarbituric Acid or Cysteine into their reversal developers. Since Cysteine appears to be non-toxic and moderately cheap, it is up to anybody to compare the results from Dithionite alone with results from Dithionite plus Cysteine. Once we see the diifference (or lack thereof), we can start answering this question.

@Alessandro Serrao : Dithionite should be very cheap and very easy to obtain. There's got to be a chemical store somewhere in Rome. Raghu's recipe probably works fine.

Unfortunately the only shop accessible with ease closed a year ago. Since I don't want, nor I do not need, to buy dithionite in lab grade purity I have to resort buying it online but this isn't a problem at all.
The important thing is to have a tried and true redeveloper recipe to use.
I've got another question: do any of you guys have noticed that, when using a fogging redeveloper, all system must be recalibrated? That is, new first development time etc...
I've noticed it using thiourea as a second redeveloper. The slides came out incredibly darker and with much higher DMax than with light re-exposure.
I've also got a Bellini Foto redeveloper handy, a prototype one to be more precise, that I never used before.
I've asked Bellini Foto for its MSDS and it lists only boric acid and sodium metaborate. Where's the reversal agent? Can I guess that is some form of boranes?
Could this https://www.solgar.it/catalogo/prodotti/amino-cisteina-500 be used with dithionite?

 

[Rudeofus]

Every component in a well-designed formula is there for a good technical reason. What is the reason for using strong solvents in the color developer of E-4/E-6 processes? PE has stated that Ethylenediamine is meant to promote dye formation and give better grain in color slide film. How's this even relevant to B&W reversal?

If you add solvent to a regular developer, it becomes more active, which means, that it builds up contrast faster and tends to create higher fog levels. E-6 color developer shall be as active as possible, and fog levels are not a concern. Since E-6 CD pH is already very high, and its CD-3 content is also very high, adding a strong solvent appears to be prudent.

There seems to be a different approach to first development in E-6 vs B&W reversal. In E-6 brightness and contrast levels appear to be mostly controlled by first developer, with all consecutive steps basically going to completion. A very active and well buffered first developer builds contrast up to very high densities, which leaves no developable silver halide in the highlights for the second developer. When looking at B&W reversal formulas, I often see very active, very high contrast and strongly restrained formulas used for second development. If you then use a Thiourea toner as second developer, there may be plenty of developable silver halide left in the highlights, and at the same time Silver Sulfide appears to yield higher densities than plain Silver. This may explain the much darker slides with extra high DMAX.

The Solgar product seems to contain mostly Cysteine plus some photographically irrelevant additives, so it's well worth trying. Since it is supplied in tablet form, one may have to dissolve and filter it before using it in a photographic bath.

PS: Boranes are extremely toxic, so they would certainly show up in an MSDS. @pdeeh states here, that Bellini most likely uses Stannous Chloride.

 

[Martin Rickards]

Cysteine is sold in health&food supplement stores, so it should be easily available. BTW raw Cysteine is a very poor silver solvent, but when in alkaline solution (such as a developer) it actually works quite well as fixer/solvent. I don't know much about Thiobarbituric Acid and its derivatives, but I would generally not look too intensively for anything with the word "barbituric" in its name.

I still haven't figured out the exact reason, but Thiocyanate and DTOD are much preferred in photographic developers over Thiosulfate. Both are easy to obtain from Fototechnik Suvatlar, although DTOD may not be shown on his price lists.

Thiobarbituric acid and indeed barbituric acid show no pharmacological activity.

 

[Raghu Kuvempunagar]

If you add solvent to a regular developer, it becomes more active, which means, that it builds up contrast faster and tends to create higher fog levels. E-6 color developer shall be as active as possible, and fog levels are not a concern. Since E-6 CD pH is already very high, and its CD-3 content is also very high, adding a strong solvent appears to be prudent.

There seems to be a different approach to first development in E-6 vs B&W reversal. In E-6 brightness and contrast levels appear to be mostly controlled by first developer, with all consecutive steps basically going to completion. A very active and well buffered first developer builds contrast up to very high densities, which leaves no developable silver halide in the highlights for the second developer. When looking at B&W reversal formulas, I often see very active, very high contrast and strongly restrained formulas used for second development. If you then use a Thiourea toner as second developer, there may be plenty of developable silver halide left in the highlights, and at the same time Silver Sulfide appears to yield higher densities than plain Silver. This may explain the much darker slides with extra high DMAX.

As I said earlier, in a well-designed formula, there is a good technical reason for including a component. PE has clearly said that for color slide film, halide solvent in second developer is there to promote dye formation and improve grain structure. But B&W reversal doesn't have to worry about dye formation. Isn't it? There is no good reason to have either DTOD, Thiocyanate or Ethylenediamine in B&W reversal second developer. As a matter of fact, Haist warns you against using them:

"If a first developer was used that did not contain an excessive amount of silver halide solvent, such as Kodak D-88, then the same developing solution may be used for the second development. Many first developers do contain sodium thiosulfate or potassium thiocyanate, and such solutions are usually unsatisfactory, often depositing a silver scum (dichroic fog) on the emulsion surface. The silver solvent in the developer results in a loss in the maximum density obtained in the positive image."