Black and white reversal: Iron Out and fixing

[pkr1979]

Hi all,

For those of you using Iron Out in the black and white reversal process - how many of you fix? And why?

I've done both, and there is a slight change in density when fixing - so I assume for long life its sort of necessary. Id also be interested to know if you, for any reason, fix some films and others not.

Cheers
Peter

 

[DeletedAcct1]

Theoretically there isn't any need for fixing after a dithionite redevelopment.

 

[pkr1979]

True, but Im not so sure thats the real life case.

 

[Ivo Stunga]

FWIW - it's said that with traditional reversal too one can do without fix for all the silver has supposedly been converted and removed. But with fixing the tone, clarity and density changes - so I always fix with my Ilford reversal to land on archival side of things. Slides are stressed during projection enough, I want to make them as archival as possible.

 

[relistan]

As I mentioned in previous discussions with @pkr1979 : IMO you should always fix the film after reversal because it's pretty unlikely that you'll manage to reach all the developable silver halides. Fixer will help to guarantee a long life for your slides.

 

[DeletedAcct1]

In replying to the OP I suggest using the fixer to its lowest practical diluition (typically 1+9) and for the shortest time, and to using an haderning fixer.

To further expand the possibilities, reversal process is feasible with a monobath.

 

[Ivo Stunga]

I suggest using the fixer to its lowest practical diluition (typically 1+9) and for the shortest time

May I ask why? Why not treat it like any other film processing and fix it as with any other film?

 

[koraks]

you should always fix the film after reversal because it's pretty unlikely that you'll manage to reach all the developable silver halides.

For instance. I think it was @Rudeofus who pointed out not too long ago in response to a similar question that if you plot a H/D curve and extend it all the way to the right, you'll notice that the density actually drops even if you'd expect it to plateau. This suggests that totally fogged silver halides do not necessarily develop out. There's ample reason IMO to suspect similar things happening on slides, and thus, silver halide from remaining even where it "theoretically" shouldn't. Note that theory generally holds true in practice quite well; the problem is just that our theory tends to be incomplete or imperfect. Although in this case, the sagging H/D curve is something that appears in the 1930s literature and was apparently perfectly well known by then. Maybe we "unremembered" it.

@Ivo Stunga's experience underlines this. Even if theory wouldn't help us here, I'd happily take his word for it.

 

[DeletedAcct1]

May I ask why? Why not treat it like any other film processing and fix it as with any other film?

Because, imho, the numbers of iporeactive silver halide crystals are few and generally way less than those in a straight negative film and, I underline imho, it suffice the use of a common fixer 1+9 or even a plain sodium thiosulfate solution (240g per liter). Minimizing the fixer exposure also reflects in minimizing the potential emlsion lift off, that would be my main concern.
Maybe I'm biased because of just that.

 

[Ivo Stunga]

or even a plain sodium thiosulfate solution (240g per liter)

I bought 25kg/55lbs bag oh the stuff for cheap, and am using 100g of it + 10g Na2S2O5 per 500ml. From a recipe I got somewhere.... That bag will last for years.
2-3min fixing time with 3 inversions every 30 seconds. Time based on leader clear time + a minute. Fixing clearly has an effect on the end result, so I don't skip it, I want my film processed properly for reasons stated above.

Minimizing the fixer exposure also reflects in minimizing the potential emlsion lift off, that would be my main concern.

The potential of emulsion leaving the base certainly is a concern with reversal. But here's my thinking (to my current knowledge):

- Nobody is reporting that developer lifts the emulsion - so we can rule it out.
- I haven't seen reports of fixer lifting emulsion - can rule it out.
- Nobody is reporting that plain clear lifts the emulsion - out it goes as a potential suspect...
-- What's unique to reversal and is often reported to soften and lift emulsion when overdone? Bleach stage, of course!

Soooo - how can I limit the bleach activity to not overdo it?
Chemical activity depends on concentration, agitation, temperature, pressure and exposure time.
Considering that pressure, agitation and temperature are set, I can only 1) reduce bleach concentration or 2) reduce bleach time.
I like some extra cash and like to avoid putting avoidable quantities of chemicals down my drain (or storage for disposal), I chose to reduce bleach concentration.
For simplicity I keep recipe exactly the same, but when bleach stage comes, I just put 1 part Water to my 1 part A and 1 part B, making my bleach 1/3 dilute.
I keep bleach time the same as in recipe - again, for simplicity and not to adjust two reversal parameters.

Result of me playing around with concentration:
- Emulsion damage went away as a regular occurrence in BW reversal with pretty much any film;
- I have extra bleach for the same money.
- I reduced the pollution to my immediate environment due to my hobby.
- I learned how underbleaching looks like and already knew what overbleaching looks like...

If emulsion damage occurs with a particular film, I note it and bleach it for a minute less the next time around.
If a particular film gets underbleached (hasn't really happened yet), I'd bleach it for a minute longer the next time around...



//I also tend to develop for box EI (by eye and my taste). Therefore I can and do engage in traditional pushing or pulling, but with reversal.
//Results as expected: increased contrast with pushing, reduced with pulling and somewhere in-between with normal processing
//Therefore I don't suffer from "Shoot film "X" at EI "Y" to be compatbile with our reversal kit/service" - it's just film processing, not alchemy.

 

[Ivo Stunga]

Although in this case, the sagging H/D curve is something that appears in the 1930s literature and was apparently perfectly well known by then. Maybe we "unremembered" it.

Possibly. I haven't read anything on processing, but I have walked the path plenty of times, keeping curious outlook and and open mind whilst fooling around with reversal stages to see exactly what step does exactly what.

 

[Rudeofus]

Soooo - how can I limit the bleach activity to not overdo it?
Chemical activity depends on concentration, agitation, temperature, pressure and exposure time.

Here is our main problem: under normal circumstances we have a few options to increase bleaching action:

1. make the oxidizer stronger: Ferric EDTA < Ferric PDTA < Ferricyanide < Permanganate/Dichromate
2. add a strong counter anion: Sulfate < Chloride < Bromide < Thiosulfate < Thiourea < Iodide
3. add a strong silver solvent: Ammonia < Thiocyanate < DTOD

The big problem with B&W reversal is, that we can't really take advantage of (2) and (3), since we want to get the metallic silver out of the emulsion, and we want to keep the Silver Bromide/Iodide in the emulsion. Therefore choosing a strong oxidizer is our only hope.

@Athiril has posted a process with Copper Chloride and an Ammonia clearing bath, which does a little of (2) and also a little of (3) and still uses a very mild bleach. If you ever have an emulsion old enough to lift off with Permanganate, then this process may solve the issue.

Regarding the original Iron Out question: the main question seems to revolve around the question, whether dithionite actually develops all the silver halide. It sure is a very strong reducer, but "most camp fires leave some charcoal behind". If anyone observes density differences after fixation, then fixation is probably a good idea regardless of what theory may tell us.

BTW there's plenty of theory about completeness of bleaching and fixation, it's also backed up by X ray analysis, but I have never even seen a credible theory, that dithionite (or any other such compound) will convert all silver halide to metallic silver.

 

[pkr1979]

Im sure its a silly question but I wonder so Ill ask it anyway. What happens if the Iron Out is added to the fix?

 

[koraks]

Im sure its a silly question but I wonder so Ill ask it anyway. What happens if the Iron Out is added to the fix?

If you use an acid fix, the sodium dithionite (the compound of interest in the Iron Out) will degrade. How rapidly, I don't know. At the same time, the silver halides you're trying to develop out are being fixed away. So you're essentially working with an unstable monobath developer/fixer. Might be fun, but difficult to make into a predictable/dependable process, I imagine.

Btw, the breakdown will involve formation of SO2, so things may get a little smelly. I personally don't mind the pungent odor of SO2 (at least in small quantities), but any people complain of prickly/burning sensations in nose and eyes, stuffed nose, headaches and general discomfort.

 

[Ivo Stunga]

@Athiril has posted a process with Copper Chloride and an Ammonia clearing bath, which does a little of (2) and also a little of (3) and still uses a very mild bleach. If you ever have an emulsion old enough to lift off with Permanganate, then this process may solve the issue.

If a film will ever present such a problem to me, I'll happily look it up and experiment - thanks for pointing out!

Up to this point however - dilute Permanganate bleach just works and film treated in it can handle re-exposure outside the Patterson reel with the subsequent reloading. With little to zero emulsion damage in perforation area, except the softest of emulsions like Foma. Foma films tend to flake a bit from the ratcheting action where BB contacts the film and digs in a bit. Image area unaffected.

 

[Rudeofus]

This matches my observations, but I have to admit, that I don't do B&W reversal very often. One thing I really have to watch out for is the poor solubility of Potassium Permanganate, and the absolutely disastrous effect, if any undissolved particles stay floating in the bleach. It's really a delicate balance between "don't mix the bleach too early, it deteriorates quickly" and "some particles seemingly take forever to dissolve".

I wonder, how much of reported "emulsion damage from permangante" was actually the result of small, undissolved particles.

 

[Ivo Stunga]

don't mix the bleach too early, it deteriorates quickly

That's why we're preparing two stock solutions in distilled water - Part A and Part B to be mixed together right before bleaching. Separately they have a shelf life of ~forever.
Quality of Permanganate matters and one should use it only when all of the Permanganate particles are dissolved. Heated distilled water will help with that. Quickly.

I make 1 liter Part A and 1 liter Part B, making sure that all of the Permanganate has been dissolved, no particles are setting to the bottom or sticking to the vessel.
When bleaching comes, I put 100ml A + 100ml B + 100ml plain water. So the 1l of A and B lasts for 10 films, timing the expiry of my mixed kit. When A and B is gone, I mix fresh Clear, Fix and Rinse Aid.

Considering that you should agitate constantly, I don't think that free-floating particles play any role in the emulsion departure to the Drain World. They'll have an effect on concentration, raising it as they dissolve.
Temperature matters. Mismatching temps could do that.

 

[koraks]

Separately they have a shelf life of ~forever.

A permanganate solution can last long - months at least - but it's not stable. In fact, it's quto-catalytically unstable, which means that once it starts to go, it'll go faster and faster. It starts with a bit of brown plating out to the sides of the bottle and then goes south from there. But there's a pretty long window where the solution remains perfectly usable, as long as it's kept away from UV. pH matters a lot; acidify the solution and it'll deteriorate 100x faster.

 

[pkr1979]

Ive switched to dichromate, which I have to say is a lot more convenient. Bleach does affect tone though, and I did read somewhere (Haist I think) that permanganate bleach is better for T-grain emulsions.

 

[Ivo Stunga]

A permanganate solution can last long - months at least - but it's not stable. In fact, it's quto-catalytically unstable, which means that once it starts to go, it'll go faster and faster. It starts with a bit of brown plating out to the sides of the bottle and then goes south from there

Thanks for correcting, I observed that discoloration once, but it probably wasn't due to time in storage. Was usable, but I didn't like the change. Regardless - I immediately switched my source of Permanganate - got better quality product and no such problems to report. Stock solution in distilled water keeps for very long time - months easily. Haven't tested it for longer periods as I keep using the stuff.
But I have a lot of Permanganate and could put one bottle in shelf, date and forget it just for the test

 

[pkr1979]

Im able to get sodium dithionite. Is there any advantage/disadvantage with that over Iron Out?

 

[koraks]

Is there any advantage/disadvantage with that over Iron Out?

The Iron Out is at least formulated to be stable in solution. The advantage of using straight dithionite is that you don't get anything in the mix that may somehow interfere with the photographic nature of the application. However, I've never heard any problems from people using Iron Out in this application, so I suspect it's a bit of a moot point. The MSDS of the product doesn't show anything I would expect to pose a problem anyway.

 

[DeletedAcct1]

A permanganate solution can last long - months at least - but it's not stable. In fact, it's quto-catalytically unstable, which means that once it starts to go, it'll go faster and faster. It starts with a bit of brown plating out to the sides of the bottle and then goes south from there. But there's a pretty long window where the solution remains perfectly usable, as long as it's kept away from UV. pH matters a lot; acidify the solution and it'll deteriorate 100x faster.

That's why it's important toadd 20gr hexametaphosphate per liter in the permagnatate solution.

 

[koraks]

That's why it's important toadd 20gr hexametaphosphate per liter in the permagnatate solution.

Thanks; to be honest, I never do this and just mix a small batch at a time. I use permanganate for clearing the DAS stain from carbon transfer prints. The 'official' documentation (Charles Berger, Sandy King et al.) suggest to use what is essentially a working stock permanganate bleach and dilute that for this particular purpose. I find this is (1) unnecessary and (2) counterproductive and simply dissolve a small amount of permanganate in plain tap water. I mix about 200ml at a time and this keeps fine for a couple of months (in the dark). I understand Calgon/hexametaphosphate can help even more; I don't have any handy and fortunately, even without this, the permanganate solution as such seems to be sufficiently stable for my needs (I've used it on occasion as a silver halide bleach as well, coincidentally!)

 

[Ivo Stunga]

the permanganate solution as such seems to be sufficiently stable for my needs

This. In my case too - I use it up before it goes brown. Even when I don't shoot for a month or two.