Wanting to try reversal processing but also not die

[mohmad khatab]

I don't know it, this has been a drawback of the permanganate bleach since many decades ago, so if no chemist found a solution...

Possibly a cold storage may help to conserve it, as in general chemical reactions are cinetics slowed with lower a temperature.

I want to know :
What is the advantage of this bleach and not available with a copper bleacher?

 

[Lachlan Young]

I always used permanganate bleach and it always worked fine. The bleach I use is made with deionised water and

1g/l Potassium permanganate
50g/l Sodium bisulfate

It's good to dissolve permanganate in half the amount of water needed and let it rest there, while giving it the occasional stir. It dissolves rather slowly and it's too dark to figure out if it has completely dissolved, so filtering the permanganate solution is a very good idea.

Before committing any films to processing that I haven't tried before, I do the first three steps of the process in full light, in q graduate. I develop a piece of film in FD, then rinse, bleach and clear. The film seems to be fully bleached in a minute or so, at 20°C. Regardless of this, I bleach for 5' and I haven't had a single case of emulsion sliding off the base, or become too soft to touch. That said, I don't remove the film from the reel and expose to light on typical Jobo and Paterson reels. Another poster said something about light fogging being uneven, but if you keep the film immersed in a bowl of water, then it will give perfectly even fogging, no marks whatsoever. I don't use any fancy high wattage lights, just a 70W tungsten bulb at a distance of 20-30cm for a couple of minutes from each side of the reel. I also spin the reel in the water while exposing to light.

I went for a dig around in some Agfa patents & found a couple of late-90's ones that have some interesting clues - the US one attached seems to give the spec for the Scala process as it existed using a dichromate bleach (though the main thrust of it is directed towards a new first developer, which looks suspiciously like there was a project to try & see if Scala could be run on machines built originally for processing E-6, presumably to broaden its popularity) - the first dev composition is very interesting, especially in what it doesn't contain - and that first developer is MQ and second developer is PQ. The use of a slightly alkaline fix and a post-hardening bath with formaldehyde is interesting too. The European patent (here's a link to the less well formatted English version on Google Patents) shows a possible approach to an acidified permanganate bleach with greater stability.

It is a very special fim, what surpirsed me is this statement in the datasheet:

"After the development you MUST use an acidic stop bath before fixing. Do NOT use plain water."

They do not say why, but perhaps the reason has a link with what you say.

Consider that in normal usage the microfilm in question is a fine grained monodisperse emulsion designed to essentially develop to completion/ a very high contrast. When it is being used as CMS 20 you do not want it to carry on developing to completion (and its very high surface area relative to the developer will ensure it'll keep going faster than you might think), but to arrest the process in a matter of seconds. An acid stop is designed to do this.

 

[Anon Ymous]

@Lachlan Young Thanks for the link/PDFs. There was this very interesting post few years ago about a long life permanganate bleach, with 20g/l of "Calgon-Photo", which is sodium hexametaphosphate. The patent bleach has 20g/l sodium potassium hexametaphosphate. I've been meaning to try this, but always forget it. Perhaps I should get serious and mix a 500ml test batch.

 

[NedL]

When this thread started, I had forgotten why I delayed trying the copper sulfate bleach. It was because I wasn't completely sure about safety and disposal of the AgCl dissolved in ammonia. I realize that producing silver nitride might be unlikely, but I'd probably be saving the waste for disposal, and I think that might be problematic since you wouldn't want evaporation to happen even on the inner walls of the storage container. It was those thoughts that stalled my testing after I'd already acquired the copper sulfate. Precipitating the silver with acid seems like a bad idea, and I'm not sure if it could be precipitated with sulfide, and I didn't want to store it for long periods, so I just stopped altogether.

There are several old positive processes that rely on silver chloride being soluble in ammonia, and silver iodide or silver bromide not being soluble.... and one that I'm aware of that relies on silver iodide being soluble in potassium iodide solution ( I think Talbot worked with a variation of this one ).

 

[mohmad khatab]

@Lachlan Young Thanks for the link/PDFs. There was this very interesting post few years ago about a long life permanganate bleach, with 20g/l of "Calgon-Photo", which is sodium hexametaphosphate. The patent bleach has 20g/l sodium potassium hexametaphosphate. I've been meaning to try this, but always forget it. Perhaps I should get serious and mix a 500ml test batch.

I have a strong feeling that I am more foolish than usual.
My foolishness and dementia increased. I do not know what to do ?

 

[Anon Ymous]

I have a strong feeling that I am more foolish than usual.
My foolishness and dementia increased. I do not know what to do ?

About what? Can you be more specific?

 

[mohmad khatab]

About what? Can you be more specific?

When I learn something new, I feel like I was a fool.
Therefore, the feeling of foolishness keeps me going.
He may sometimes go up and down sometimes, but in general, he is always with me, and is a good catalyst for learning and more research.
- But ,,
I want to do an important test.
- I want to bleach part of a movie using permanganate and another part using copper bleach, and I want to explore the difference between the two in terms of bleaching quality.
I want to check this case.
- But I am currently isolated from the world and I do not have a black and white film and I am waiting for some time in order to get a black and white film in order to take this test.

 

[Donald Qualls]

To be clear, at no point was I criticizing others who used differential solubility to remove a rehalogenated image and leave undeveloped halide in place -- it just seems like rehalogenating and then an additional bath in ammonium hydroxide solution is more work than directly dissolving the developed silver and I don't see copper sulfate as a huge improvement over potassium permanganate. What I'd use for B&W reversal? At present, probably acidified peroxide. Nothing particularly hazardous in storage (even 9% isn't any more hazardous than stop bath concentrate). I've used dichromate bleach in the past, it works very well but I prefer something less aggressively anti-biology if I have the choice. @mohmad khatab you can almost certainly get 3% peroxide locally, and may be able to get 9% or 12%.

 

[Anon Ymous]

Why not use three times as much 3% peroxide instead of 9%?

 

[138S]

When it is being used as CMS 20 you do not want it to carry on developing to completion (and its very high surface area relative to the developer will ensure it'll keep going faster than you might think), but to arrest the process in a matter of seconds. An acid stop is designed to do this.

There is no need to arrest development instantly... if water bath takes a bit more time to stop development then we can slightly shorten development time, may be there is another reason.

It may be something about fixing....

 

[138S]

I want to know :
What is the advantage of this bleach and not available with a copper bleacher?

Probably the copper bleacher is the best technically. I did all sorts of experiments with permanganate and dichromate to bleach CMS 20 with no good results, but the copper bleach works with CMS 20, removing metallic silver without damaging the silver halide, as Raghu teached me.

With regular pictorial film copper bleacher may have an slight plus as it may conserve better highlight detail as it is able to not disolve the smallest halide crystals, like those in CMS 20.

In fact dichromate is reportedly better for that than permanganate. But the challenging job is with CMS 20, with such small crystals bleaching has to be very selective to not damage the silver halides.

 

[mohmad khatab]

Probably the copper bleacher is the best technically. I did all sorts of experiments with permanganate and dichromate to bleach CMS 20 with no good results, but the copper bleach works with CMS 20, removing metallic silver without damaging the silver halide, as Raghu teached me.

With regular pictorial film copper bleacher may have an slight plus as it may conserve better highlight detail as it is able to not disolve the smallest halide crystals, like those in CMS 20.

In fact dichromate is reportedly better for that than permanganate. But the challenging job is with CMS 20, with such small crystals bleaching has to be very selective to not damage the silver halides.

I partially agree with you,
But you have not tested anhydrous copper sulfate.
It can do the job with precision and go into the smallest details.
Unfortunately, many colleagues do not mention anything about the significant differences between these two copies of copper sulfate,
Anhydrous is very expensive, and its results are very excellent,
I used it in a negative color and its results were great, but the problem is that it needs pre-bleach and a cleansing solution after bleach. (This is the problem, you need three steps instead of one step)

 

[138S]

I partially agree with you,
But you have not tested anhydrous copper sulfate.
It can do the job with precision and go into the smallest details.
Unfortunately, many colleagues do not mention anything about the significant differences between these two copies of copper sulfate,
Anhydrous is very expensive, and its results are very excellent,
I used it in a negative color and its results were great, but the problem is that it needs pre-bleach and a cleansing solution after bleach. (This is the problem, you need three steps instead of one step)

To be clear, I've never tested any kind of copper sulfate, I've always used (mainly) dichromate and some permanganate, but with those I failed with CMS 20, Raghu kindly explained his recipe for CMS 20 that I'm to try next time I will reverse that film.

I used it in a negative color and its results were great, but the problem is that it needs pre-bleach and a cleansing solution after bleach. (This is the problem, you need three steps instead of one step)

Well, dichromate and permanganate use two bath, not one, clearing bath is also necessary, so three steps instead two.

 

[mohmad khatab]

To be clear, at no point was I criticizing others who used differential solubility to remove a rehalogenated image and leave undeveloped halide in place -- it just seems like rehalogenating and then an additional bath in ammonium hydroxide solution is more work than directly dissolving the developed silver and I don't see copper sulfate as a huge improvement over potassium permanganate. What I'd use for B&W reversal? At present, probably acidified peroxide. Nothing particularly hazardous in storage (even 9% isn't any more hazardous than stop bath concentrate). I've used dichromate bleach in the past, it works very well but I prefer something less aggressively anti-biology if I have the choice. @mohmad khatab you can almost certainly get 3% peroxide locally, and may be able to get 9% or 12%.

Thank you, my dear brother.
God bless you.
In fact, the peroxide I have is the industrial version and it's at 70% concentration.
In the end, I do not have to use such bleach, I am basically not convinced in principle.
I have anhydrous copper sulfate and it works perfectly in a very elegant style. And has a long life.
I do not find any additional advantage that peroxide possesses while copper bleach does not have it (in my view).
My greetings

 

[Lachlan Young]

@Lachlan Young Thanks for the link/PDFs. There was this very interesting post few years ago about a long life permanganate bleach, with 20g/l of "Calgon-Photo", which is sodium hexametaphosphate. The patent bleach has 20g/l sodium potassium hexametaphosphate. I've been meaning to try this, but always forget it. Perhaps I should get serious and mix a 500ml test batch.

That particular patent does seem to have popped up here and elsewhere a few times over the years, but almost nobody seems to have tried it to see if it works. I think that either agent may be very close to each other in practical performance terms.

I'm quite intrigued by the first developer disclosed in the other patent (italics and bold mine):

4.5 g hydroquinone
11.0 g potassium sulphite
41.7 g potassium carbonate
1.5 g sodium carbonate
5.5 g potassium hydroxide
2.0 g nitrilotriacetic acid
1.6 g potassium bromide
67 mg benztriazole
3.8 g. N-methyl-4-aminophenyl-hydrogen Sulphate (metol)
0.4 ml hydroxyethane-diphosphonic acid
1.2 g polyethylene glycol, molecular weight 1500
2.0 g Sulphuric acid
made up with water to 1 litre; pH 10.2

The lack of traditional grain solvent ingredients is intriguing - the ingredients I have italicised seem to be chelating agents & probably don't play a part, but the polyethylene glycol of specified molecular weight seems to be quite an important ingredient - indeed in the modified developer using HQMS or something similar, it calls for a totally different molecular weight of PEG. This makes me wonder if PEGylation (or something like that) is being used to ensure that the developer is able to keep working until all the silver is developed without requiring additional silver solvent. Given Agfa's relationship to Bayer, I wouldn't be totally surprised if drug delivery methods had been investigated for their potential use in photographic processes.

There is no need to arrest development instantly... if water bath takes a bit more time to stop development then we can slightly shorten development time, may be there is another reason.

It may be something about fixing....

Doubtful - it's more likely for the same reason you need an effective stop bath when lith printing - to arrest the infectious development before it crashes every value above a certain level of exposure to pure black. CMS 20 has more in common with a litho emulsion than a pictorial emulsion. There may also be an oxidation product formed from a water stop that causes problems (likely fogging) that would not be the case with an acid stop.

 

[Donald Qualls]

@mohmad khatab I understand you've gotten better results with anhydrous copper sulfate than with the hydrated crystalline form -- but if both are of equal purity this should make no difference, other than requiring you compensate the weight of crystals relative to the weight of anhydrous to account for the included water of hydration (just as I do when I use 20 Mule Team laundry borax -- the decahydrate -- in place of anhydrous sodium tetraborate in a developer). What I presume has happened in your case, then, is that the anhydrous copper sulfate you have is of better purity than the crystalline product you can obtain, or just possibly the crystals contain some specific impurities that inhibit the bleaching action or otherwise cause trouble in the process.

 

[mohmad khatab]

@mohmad khatab I understand you've gotten better results with anhydrous copper sulfate than with the hydrated crystalline form -- but if both are of equal purity this should make no difference, other than requiring you compensate the weight of crystals relative to the weight of anhydrous to account for the included water of hydration (just as I do when I use 20 Mule Team laundry borax -- the decahydrate -- in place of anhydrous sodium tetraborate in a developer). What I presume has happened in your case, then, is that the anhydrous copper sulfate you have is of better purity than the crystalline product you can obtain, or just possibly the crystals contain some specific impurities that inhibit the bleaching action or otherwise cause trouble in the process.

I do not buy cheap copper sulphate recycled from copper waste.
Copper metal is available in Egyptian mines.
The copper sulfate purity is 99.97%, and it is the production of a government company that has a quality certificate and a certificate from the National Chemistry Authority that does not give any certificate except based on accurate tests.
- As for the anhydrous copper sulfate, I did not reduce the amount based on calculating the difference between the number of water parts in this type and the number of water parts in the other type.
I did not do that .
I have prepared the copper bleach without any calculation at all.
In that case, you can say that I indirectly increased the quantity. No problem, and why not? There is no scientific or practical objection stating that the quantity may not be increased by that slight percentage.
Perhaps the slight increase in the quantity is what helped in obtaining better, more accurate and possibly better results.
This formula is not sacred, it can allow some slight increases or decreases. This is bleached and not developed, allowing it to accept these slight excesses.
We called it a new name from Egypt in my composition, its name is no longer copper bleach, its name (wild bleach).
- I am happy to have these results.
Greetings to you from Cairo, isolated from the world.

 

[removed account4]

other than requiring you compensate the weight of crystals relative to the weight of anhydrous to account for the included water of hydration (just as I do when I use 20 Mule Team laundry borax -- the decahydrate -- in place of anhydrous sodium tetraborate in a developer)

hi, sorry to derail the conversation

Donald -
Do you have a rule of thumb/ factor to multiply store bought borax or washing soda ( or baking soda ) from the grocery store by as it sits around
and absorbs moisture, in relation to lab grade that is dry ?

Thanks in advance
John

 

[Donald Qualls]

Why use a rule of thumb? The formula for copper (II) sulfate (anhydrous) isn't complex, the atomic weights of the elements is easy to find (though I don't have them memorized for other than the top rows of the periodic table, through nitrogen). the amount of hydration is also easy to find, it's always the same (though I don't offhand recall what it is). Then it's just (species + water) / species -- and you'll use the same basic fraction to compensate any chemical for hydrate vs. anhydrous.

 

[Anon Ymous]

@Lachlan Young Yes, the italicised compounds are NTA and HDPE respectively, both chelating agents. The PEG 1500 compound is used as a development accelerator, which helps clear the highlights. This comes from the patent text, page 3, after the "55" marker:

Surprisingly, it was found that only the addition of polyglycols as development accelerators resulted in a considerably improved complete development of the shadow region after first development, and thus resulted in an improvement in the clarity of the light regions after reversal development. Apart from this advantage, however, it proved to be a disadvantage when using polyglycols that almost all the polyglycols, when used in the requisite amounts, resulted in significantly reduced maximum densities after reversal development. As shown in examples 6 to 12, compared with polyethylene glycols P1000, P1500, P4000 and P12000 the use of polyethylene glycols P200 and P400 resulted in the lowest loss of maximum density, so that P200 and P400 appeared to be the most suitable for this developer. All further investigations were therefore performed using P400 as the development accelerator."

 

[138S]

The PEG 1500 compound is used as a development accelerator, which helps clear the highlights.

What I understand is that the effect we need is promoting enough infectious development in the first development and in the second development. In the emulsion we have a share of silver halides that won't be developed from the pictorial latent image, some literature call it "Silver Reserve". Perhaps those crystals where not well dye sensitized or failed to take an speed boost from other chemical operations in the emulsion making...


That Silver reserve if not developed in the first development may build fog after fogging the halides. May view is that we have two jobs to do with silver reserve:

> In the first development we have to proportionally developing them via infectious development to add contrast and increase highlight DMax after 1st development that after bleaching will result in clear highlights

> The other job is in the second development, also infectious developing that Silver Reserve proportionally to increase DMax while not building fog, we have to not develop that silver reserve in the highlights !!!


The DR5 guy is the master nº 1 in this business, he reverses magistrally any kind of BW film (with CMS 20 exception, I guess his bleaching is not compatible, copper required, the other exception is was Neopan), I feel that his success is from optimally managing the Silver Reserve, and finely enhancing both thinning any fog and boosting DMax from the right infectious development and from a wise toning.

hmmm... mastering all those films is an insanely well done job : http://www.dr5.com/blackandwhiteslide/filmreviewdev1.html


Still, I'm trying to learn if second exposure has to be dosified to not expose too much that Silver Reserve, if we build fog from it then we'll need more light power in the projection. What is clear is that if fogging and 2nd developing all to completion then we'll build fog


Making slides for scanning it's easy, making beautiful slides for projection is an art.

Probably, projection of beautiful BW slides is one of most powerful imaging we can do, it has all necessary ingredients, including autheticity.

Personally, some of the images I made with reversal are the ones I love the most, but still I have to learn a lot to make optimal slides for projection.

 

[138S]

Doubtful - it's more likely for the same reason you need an effective stop bath when lith printing - to arrest the infectious development before it crashes every value above a certain level of exposure to pure black. CMS 20 has more in common with a litho emulsion than a pictorial emulsion. There may also be an oxidation product formed from a water stop that causes problems (likely fogging) that would not be the case with an acid stop.

The water bath stops development 10 seconds later than acid stop bath, then the effect of 10s more of development (regular and infectious) is irrelevant as we can shorten development stage by 5 seconds.

CMS 20 development has a long time like other films, 10 s more more less in a 10min development is not a concern.

But CMS 20 fixing is 30s only !!!! depending on the fixer pH it may have an effect. I don't know if datasheet asumes a kind of fixer for that recommendation.

 

[Anon Ymous]

@138S All films have a minimum and a maximum density. For a given developer, when used as a FD in reversal processing, increasing development time will increase contrast, but also give clearer highlights. Increasing silver solvent quantity will also give clearer highlights. You need to experiment with development time and silver solvent quantity for every film you'd like to use. You can't really adjust fogging reexposure, it's not practical. You fully fog whatever is left, either using light, or chemically. If you still get high minimum density, then you have to adjust something at the FD stage.

 

[Lachlan Young]

The PEG 1500 compound is used as a development accelerator, which helps clear the highlights. This comes from the patent text, page 3, after the "55" marker:

I'd read that, spent the afternoon looking for any other cases where it was used for that purpose, then promptly failed to put it in my reply... Not a hugely expensive component, so probably worth trying out.

 

[Lachlan Young]

The DR5 guy is the master nº 1 in this business, he reverses magistrally any kind of BW film (with CMS 20 exception, I guess his bleaching is not compatible, copper required, the other exception is was Neopan), I feel that his success is from optimally managing the Silver Reserve, and finely enhancing both thinning any fog and boosting DMax from the right infectious development and from a wise toning.

CMS 20 runs well in Scala with only an alteration of the first developer time - the contrast is relatively higher than some films, but it reverses just fine. It suggests that the Agfa process is rather better worked out than the DR5 one in terms of its universality. And that PEG 1500 may be the special ingredient we've all been looking for...

As for CMS and stop baths, the ADOX documentation is pretty explicit about the risks of uneven development in even toned areas being greater with CMS 20/ repurposed document films - and we have material evidence that even with regular films, smooth grey tones can show uneven densities when water is used in place of a stop - thus ADOX want to reduce the risk of customers complaining about their densities being uneven across the roll. CMS 20 mishandled (intentionally in this case) & run in a more 'normal' developer can produce some spectacular bromide drag.