Potassium Permanganate based reversal for ortho litho film

[grainyvision]

So I'm getting into alt-process stuff but basically hate the typical digital side for getting large format negatives. 95% of my pictures are on film, so why not go all analog.

I've done a little bit with negative -> interpositive -> contact printing large negative. The process is pretty annoying though. Doing direct reversal (ie, printing negative to bigger negative) is much more appealing, but in my first test run I've had a number of annoyances and questions. I'm avoiding dichromate because reading the MSDS of it makes permanganate look like an angel, though of course I'm taking extra precautions with permanganate as well.

Formula/process I found that I'm trying to use:

Bleach - 50g potassium permanaganate, 50ml sulfuric acid (substituted with 122ml of 40%), to 1L of water
Clearing bath - 50g sodium metabisulfite to 1L of water

First developer, citric stop bath, rinse, bleach for 1m for ortho litho film. rinse well, then clear until film is completely white and clear with no dark density remaining (usually 2-3m), rinse well, second developer, citric stop bath, TF-5 fixer, final rinse

Anyway, so some questions and concerns:

1. Why does the permanganate bleach require so much sulfuric acid? I seem to be getting full bleaching in 1m with ortho litho film. Is it possible to reduce the amount? Would this just reduce speed of bleaching or actually affect stability?
2. How does one check if all of the permanganate has gone into solution during mixing? I have a magnetic stirrer and probably stirred for 10m or so but there was still a lot of gunk at the bottom of my beaker. Didn't seem to affect results though
3. I'm using a clearing bath of 50g metabisulfite to 1L of water. It's obnoxiously smelly with sulfur dioxide. I added 200ml of water and 1g of baking soda to the solution to try to make it a bit more stable. Still smelly but not singe your nose hairs smelly. Is this safe to do though? What is the harm in increasing the pH? Is there some threshold I should be careful of or an ideal buffering system I should make to keep it good for the process but to release as little sulfur dioxide as possible?
4. It seems at least some of the permanganate during mixing will become magnetic magnesium which is.. non-ideal with a magnetic stir bar. What's the best way to get rid of this? I used a shallow bath of straight sulfuric acid (mine is 10N/40%) but it took quite a while. Is there something a bit less crazy that'll make it soluble?
5. I used liquidol 1+9 as the first developer and 2nd developer. It's a bit too high contrast, but that's not important for this, I know how to tweak that. However, I found that after 2nd developer the emulsion gets super extremely soft, including a weird backside emulsion that I didn't even know existed. The emulsion swells so much that I can see raised lines along the image. I added 8g of sodium sulfate to the developer and the emulsion was still fragile, but was good enough to handle without damaging. Is there anything else that can be done to ward off this effect?
6. I found that using stop bath (some amount of citric acid, unmeasured) the emulsion would harden up really well, but then going into TF-5 fixer it'd turn soft again. I know that going back into citric acid from here would result in a reaction with the TF-5... but is it possible to basically skip the fixer since this is suppose to be developed to completion anyway?
7. Again on hardening the emulsion, I found that after doing final rinsing, doing a quick dip into my citric acid stop bath then a bit more rinsing would result in a much easier to handle emulsion. Is there any harm in doing this? I don't care about super archival contact printing negatives, but I don't want them to fade in a week either.
8. Whats the best way to dispose of the used bleach? I noticed that neutralizing the bleach and then using a 20% solution of sulfite will cause all of the permanaganate to be converted to magnesium, but then that's a mess in itself to clean up with trays. Is magnesium a safe/non-reactive target I can just filter off and trash if I want to avoid flushing permanganate down the drain?

 

[Anon Ymous]

50g potassium permanganate + 50ml sulfuric acid in 1l final volume? This is insanely strong. 2g of permanganate and 10ml of sulfuric acid is what Ilford proposes for reversal processing and is already plenty strong. In fact some people have reported having problems with some less than ideally hardened films. You can even go to 1g/l of permanganate and still have a perfectly capable bleach. Using a lower amount of sulfuric acid (than 10ml/l) will make it slower, but still usable. The bits of undissolved permanganate can simply be filtered out. Funnel, coffe filter and that's all. That's what I'm doing. Your clearing bath is also very strong, Ilford's proposition is for 25g/l. You can still go lower than this, but don't go too low. If your film becomes too fragile, you can try using an acid hardening fixer.

 

[Raghu Kuvempunagar]

50g potassium permanganate + 50ml sulfuric acid in 1l final volume? This is insanely strong. 2g of permanganate and 10ml of sulfuric acid is what Ilford proposes for reversal processing and is already plenty strong.

+1

 

[grainyvision]

50g potassium permanganate + 50ml sulfuric acid in 1l final volume? This is insanely strong. 2g of permanganate and 10ml of sulfuric acid is what Ilford proposes for reversal processing and is already plenty strong. In fact some people have reported having problems with some less than ideally hardened films. You can even go to 1g/l of permanganate and still have a perfectly capable bleach. Using a lower amount of sulfuric acid (than 10ml/l) will make it slower, but still usable. The bits of undissolved permanganate can simply be filtered out. Funnel, coffe filter and that's all. That's what I'm doing. Your clearing bath is also very strong, Ilford's proposition is for 25g/l. You can still go lower than this, but don't go too low. If your film becomes too fragile, you can try using an acid hardening fixer.

Doh! Forgot to mention the bleach is diluted 1+9, so working solution ends up being 5g PP and 5ml SA.

Good point about hardening fix. Is it possible to harden as a separate solution? I have some pot alum but had rather not keep around a very rarely used hardening version of TF-5

 

[revdoc]

You might want to consider trying single-tray processing. That's what i do, and the film doesn't need to be touched at all until the end of the final wash. Cuts down the risk of scratching.

Secondly: no, you don't have to fix. Second development is to finality, so there's no halide left to fix. If you need a hardener, you can buy Heico hardener separately. It just needs a mild acid environment to work. Otherwise, chrome alum is better than potassium alum, but both are okay.

Thirdly: the sulfuric acid in the bleach supplies sulfur, to convert the silver metal to soluble silver sulfate. I replace it with sodium bisulfate (pH down, from a pool supply shop). Works just as well.

BTW, I make enlarged negs on ortho litho film using dichromate bleach, and never have problems with scratching. My process: first dev, print developer for 4 minutes; plain water rinse twice; bleach until the image is gone, about 45 seconds; rinse twice; clear 4 minutes in sodium sulfite; rinse twice; second dev, same as the first; rinse; then wash for 10 minutes. All in one tray.

 

[relistan]

You do need to fix. In Haist's chapter on reversal processing that I recently read, he says it's basically impossible to expose and develop all of the silver in an emulsion even with reversal.

 

[grainyvision]

You do need to fix. In Haist's chapter on reversal processing that I recently read, he says it's basically impossible to expose and develop all of the silver in an emulsion even with reversal.

What would be the harm of not fixing though in that case? Seems like the dmax would just slightly intensify over time without fixing.

I had a completely new go at this process, including a nasty conversion process for the bleach I had made previously to make it safe to dispose of. The biggest reason to NOT follow the formula I found is because it'll not only decay but also release oxygen gas at an alarming rate. I went back to it 24 hours later and my plastic bottle was extremely bulged. I ended up neutralizing with ferrous sulfate and oxalic acid, but ascorbic acid is much more efficient it seems.

Either way, I followed pretty much the Ilford formula for bleach, but a bit more concentrated. I used oxalic acid for the clearing bath rather than sodium metabisulfite. This produced no odor at all during clearing (in theory produces some CO2), but otherwise seemed to work the same. The first developer used is similar to D67, but with an accidental over addition of benzotriazole and additional thiocyanate to compensate, and less developing agents to tame down the contrast of ortho litho film. The modified D67 appeared to be too solvent, giving dichroic fogging, but after bleaching and clearing there is no problem with some sludging. The 2nd developer I used ~4 tablespoons of powdered iron out cleaning product (active ingredient is sodium dithionite), with a little baking soda and triethanolamine added to make it more active (pH was ~8) and the triethanolamine makes it so it has a tray life of maybe 1 hour rather than several minutes. I didn't bother measuring. The primary plus of using this as the second developer is that due to the low pH used, the emulsion doesn't get too soft. I then skipped fixing and just rinsed from there. To dispose of the bleach, add some ascorbic acid until the solution is completely clear.

Formulas

Bleach part A:
Add 8g of potassium permanganate to 500ml of water

Bleach part B:
Add 100ml of 40%/10N sulfuric acid to 400ml of water (making 500ml total)

Usage: 100+100+300 to make 500ml of working solution bleach

Clearing solution:
Add about 5g of oxalic acid about 500ml of water. Ratios here aren't so important as metabisulfite, as oxalic acid won't be too acidic and adding too much won't release any noxious gas

Usage: Can be mixed in a tray with no real care about precision

Modified Kodak D67 (Kodak D19 + Thiocyanate)

• Metol 1.5g
• Sodium Sulphite (anhyd) 90g
• Hydroquinone 5g
• Sodium Carbonate (anhyd) 45g (54g monohydrate)
• sodium thiocyanate 3.3g
• Potassium Bromide 3g
• BZT 1%, 2.5ml (intended to use just 0.1%, but still works
• Water to 1 litre

Usage: Use undiluted, should last a while in a closed container. For Arista Ortho Litho, develop for 2m in a tray when printing from normal contrast negatives, develop for 3-4m when printing from lower contrast negatives. Agitate first 30s, then 4x every 30s

Second developer:
* 500ml of water
* ~15ml of triethanolamine 99%
* ~3 tablespoons of iron out cleaning powder (sodium dithionite + sodium metabisulfite)
* ~1 tablespoon of baking soda

This was eyeballed. Add more iron out and baking soda as needed. Solution will turn yellow as it decays, if it's a darker brownish yellow, it's likely gone off completely.

Process:

* Expose the film, this developer appears to increase the speed of the film by at least 1 stop
* Rinse the film to remove antihalation dye
* First developer for 2-4m depending on contrast aim
* Citric acid stop bath
* Rinse
* Bleach for 1m
* Rinse well until all purple is gone (do not worry if there is brown stains on the back, this will come out in the clearing bath)
* Clear for 1-2m, until all traces of brown is gone and the film appears white
* Rinse
* Second developer for ~5m, or as needed. Check the back of the film for "true" density, The borders should appear somewhat silvery but also rather dark and not a mild grey
* Rinse
* Optionally fix
* Final rinse

The results came out great with ortho litho film, though I think the 2nd developer could be better. I might revert back to Liquidol or another paper developer with sodium sulfate added to reduce swelling. Although with the iron out developer the emulsion wasn't overly fragile, there is very real "texture" to the final dried film, holding it at an angle the black lines of the image etc are visibly lifted from the film base.

Example attached

 

[relistan]

@earlz regarding fixing... no, it will darken wherever silver halide remains, most likely in the highlights. If the first developer didn't reach it even with solvent, then it won't be bleached and also the less aggressive second developer (with no solvent) is not likely to develop it.

 

[Raghu Kuvempunagar]

There's a nice writeup on the subject of producing enlarged inter-negatives by reversal processing by Liam Lawless.

 

[grainyvision]

There's a nice writeup on the subject of producing enlarged inter-negatives by reversal processing by Liam Lawless.

This is actually the guide I used. Again I must warn DO NOT use the permanganate formulas listed there, though the process itself seems to work well. It recommends combining permanganate with sulfuric acid and does not indicate that the solution is NOT SHELF STABLE. The solution will release rather significant amounts of oxygen gas and presents a huge burst risk! The clearing bath he lists also will produce annoying and dangerous amounts of sulfur dioxide gas! I've seen this exact resource published at least 4 different places, all with the same formulas and mostly the same process. The dichromate formulas might work well, but the permanganate formulas he gives are straight up dangerous

 

[grainyvision]

@earlz regarding fixing... no, it will darken wherever silver halide remains, most likely in the highlights. If the first developer didn't reach it even with solvent, then it won't be bleached and also the less aggressive second developer (with no solvent) is not likely to develop it.

It'd likely be more trouble than it's worth, but would a fogging developer such as dithionite, combined with some silver solvent and maybe hydroquinone (if it can regenerate it) be active enough to reach it? I know one of the 2nd developer formulas Kodak used was a pure hydroquinone developer, but using hydroxide to set an extremely active high pH, which I imagine is actually strong enough to reach every bit of silver halide. My concern there is that I can't see how the emulsion wouldn't float off in the tray considering how soft it gets with carbonate balanced pH. I've wondered if amidol or some other "near neutral" developer would work well for a low pH fogging developer, but I don't have any amidol and staining would be a concern. Unsure what other low pH developers there are

 

[relistan]

Dithionite should do it from what I understand. This also removes the chance that you might not have gotten perfect second exposure also.