Wanting to try reversal processing but also not die

EASmithV · Mar 31, 2020

Hey everyone,

This damn plague has me getting back to stuff I stopped being able to have time for: photo stuff!
I've always wanted to try reversal processing, especially 8mm and 16mm. I figured I can try the bucket method and just stack up some black buckets and shuffle the stack per each step but there was a few basic questions I had before I get started.

I think I'm going to try a 1:25 or 1:50 dilution Rodinal for the development, I'm not sure what film stock I'm going to use, but probably going to experiment with a few random sheets and some 135 before I try any cine.. Maybe xray too.

I know that there's two types of reversal bleach, a dichromate and a sulfuric acid one? I feel competent enough to mix the chemistry, but my ventilation is very poor. I basically have just a blocked up small bathroom I use mainly for loading sheet film with a very poor exhaust fan low on the wall. My plan was to use black buckets and darken the surrounding rooms and basically not be present in the room except when changing chemistry, etc. For better light proofing, I will close the door behind me. I was planing to design some sort or rocking mechanism for agitation.

My questions are as follows:

When dissolved are there dichromate fumes to be concerned about or is it only so hazardous in powdered form? I can mix the chems outdoors. If I go the sulfuric acid route, will there be more / less fumes? Are there precautions to do this safely, or is it unwise to attempt without a full blown vent hood or larger room?

Is it possible to use a different acid (vinegar / acetic acid), and just extend my bleach times significantly?

Are there any other alternate formulas, special safety considerations, or general thoughts on doing something like this?

Anon Ymous · Mar 31, 2020

First things first: There's a potassium bichromate bleach and a potassium permanganate bleach. Both need sulfuric acid. Potassium bichromate is a carcinogen, you may want to take this into account. Proper disposal of this bleach is a must. Both permanganate and bichromate are solids, there are no fumes, but when mixing these bleaches some finely powdered particles may become airborne, so breathing them can be a problem. Once in solution, this danger is gone, but skin contact should always be avoided, nitrile gloves should be used. The bichromate bleach is more fool proof; the permanganate bleach is far safer, but can soften the emulsion a bit too much in some cases. The problems usually occur with not very well hardened films. All films by mainstream companies are adequately hardened, but using half strength (1g/l) permanganate is a good idea. It has never failed in my experience.

Now, Rodinal isn't exactly the best choice for developer, but could probably work in the right dilution, provided that a silver solvent is added. This can either be potassium thiocyanate, or sodium thiosulfate. 1+50 is too weak, perhaps 1+25 is also weak. A stronger dilution, perhaps 1+10, would be closer to the ideal. If you have Dektol, or D19, then you can use them instead of Rodinal, with the addition of a silver solvent. Basically, you need a strong, high contrast developer, print developers fit the bill.

Reversal processing isn't too hard, but needs some experimentation regarding development times and silver solvent levels. Go for it, but shoot some 135 film for tests, you will need them.

mohmad khatab · Mar 31, 2020

I agree with the opinion of my respected colleague Mr. Anon Ymous.
I tried to go through that experience, but I was kinda idiot.
I used permanganate with sulfuric acid 99% concentration while it required only 37% concentration, and this is what caused the negative.
By and large, the story was somewhat successful with me when I used copper sulfate with sodium chloride, but I was avid and wanted to get more - and it became clear to me that the bleach solution was not the reason for the low quality. .

Therefore, I advise you to use copper bleach, it is environment friendly and does not cause cancer and deals with negativity with great tenderness and lives a very long life.
The crazy formula for copper bleach:
300 ml deionized water 80 ° C.
180 grams copper sulfate
180 g sodium chloride (without iodine)
5 ml sulfuric acid 37%
Water up to 500 ml
We wait for it to cool down, then filter it with the coffee filter twice and then use it without problems.

mohmad khatab · Mar 31, 2020

I am waiting for you to say thank you

Donald Qualls · Mar 31, 2020

There's another reversal bleach that's much more innocuous than either permanganate, dichromate, or copper sulfate: hydrogen peroxide. I've seen several versions of this on YouTube; the simplest version uses drug store 3% peroxide and vinegar (stop bath should work). First develop as usual, water rinse, then thirty seconds in the acid bath and 2-3 minutes in the peroxide (at this point, you can work in the light, just transfer the spiral between two tanks or even a bowl). Repeat the acid and peroxide until the parts of the film that had been black are fully clear. By now, the undeveloped halide ought to be well exposed, so you can repeat the water rinse (to remove traces of acid and peroxide) and back into the first developer (or you can use a different developer for the redevelop, there are as many options here as there are in processing negatives). After developing, there should be no halide remaining, but if you want to be very sure, fix normally, and wash as you usually would.

No carcinogens, nothing particularly hazardous to handle. I've done reversal with dichromate bleach -- and honestly, I don't like using the stuff, it makes me paranoid knowing it's both acutely toxic and carcinogenic. Permanganate isn't much better (though it's handy to have around if you need to light a fire). The 3% peroxide from the drug store shouldn't be swallowed and needs to be kept out of your eyes -- which matches everything else in a regular black and white darkroom.

mohmad khatab · Mar 31, 2020

Donald Qualls said:
There's another reversal bleach that's much more innocuous than either permanganate, dichromate, or copper sulfate: hydrogen peroxide. I've seen several versions of this on YouTube; the simplest version uses drug store 3% peroxide and vinegar (stop bath should work). First develop as usual, water rinse, then thirty seconds in the acid bath and 2-3 minutes in the peroxide (at this point, you can work in the light, just transfer the spiral between two tanks or even a bowl). Repeat the acid and peroxide until the parts of the film that had been black are fully clear. By now, the undeveloped halide ought to be well exposed, so you can repeat the water rinse (to remove traces of acid and peroxide) and back into the first developer (or you can use a different developer for the redevelop, there are as many options here as there are in processing negatives). After developing, there should be no halide remaining, but if you want to be very sure, fix normally, and wash as you usually would.

No carcinogens, nothing particularly hazardous to handle. I've done reversal with dichromate bleach -- and honestly, I don't like using the stuff, it makes me paranoid knowing it's both acutely toxic and carcinogenic. Permanganate isn't much better (though it's handy to have around if you need to light a fire). The 3% peroxide from the drug store shouldn't be swallowed and needs to be kept out of your eyes -- which matches everything else in a regular black and white darkroom.

Never heard this bleach before.
Did you try it yourself?
Generally speaking, it is very very cheap according to your recipe, but it will only last for one negative, I think.
I don’t really know ,,
However, the copper bleach is great, great, and very practical.
I personally used it in C41 before and its results were good ,, here I am saying good and not very good or excellent.
At the time, I used anhydrous copper sulfate, not hydroponic copper sulfate. And there is quite a difference in the price. But the results were, of course, better than using aqueous copper sulfate.
Of course, here we are talking about the process of developing a negative color, not black and white, and dealing with a negative color is more complicated and requires greater accuracy and flexibility. Therefore, the anhydrous copper sulfate was good and a few kilometers away from becoming very good.
And with the use of this copper bleach with black and white it was really excellent.

NedL · Mar 31, 2020

Wish PE or Jerry Koch were still here to chime in, but I've stayed away from mixing hydrogen peroxide and acetic acid due to the possibility of forming paracetic acid. Several of us have used citric acid and hydrogen peroxide for paper reversal, and I think it's been used for film as well. There's a long thread about it somewhere here at photrio. I've been meaning to try the copper bleach, but with sodium bisulfate.... got as far as purchasing the copper sulfate...

revdoc · Mar 31, 2020

Just to add one more point: you can replace sulfuric acid in dichromate and permanganate bleaches with sodium bisulfate. It's available from pool supply stores as pH reducer.

Raghu Kuvempunagar · Mar 31, 2020

Copper Sulphate (+ Sodium Chloride + Sulphuric Acid) bleach works fine for b&w film reversal though it's a little slow compared to Dichromate bleach. It has good capacity can be reused several times. I use the formula given here:
http://real-photographs.co.uk/formulae/toners/copper-sulfate-bleach/

Unlike other bleaches Copper Sulphate bleach adds an additional step - a two minute rinse in 2% ammonia after the treatment with the bleach.

You can substitute Sulphuric Acid with appropriate amount of Sodium/Potassium Hydrogen Sulphate if you want to avoid dealing directly with the acid.

Athiril posted details of Copper Chloride bleach for film reversal in a previous thread and you may want to refer to it.

removed account4 · Mar 31, 2020

Here's the video/thread peroxide approach Donald and Ned referred to.
https://www.photrio.com/forum/threads/reversal-print-processing-video-new-approach.153447/
The "trick" is to have the right amount of citric acid. too little it won't clear, and too much it won't clear...
It's a little bit of the Goldilocks situation ...

Raghu Kuvempunagar · Mar 31, 2020

There's one more bleach for film reversal though uncommon - Cerium Sulphate bleach. You can find the details of this bleach in an article by Yurow on Unblinkingeye site. It's a safe bleach compared to other bleaches though much more expensive.

It tried it a couple of times but wasn't quite happy with the results. But that could be due to the quality of Cerium Sulphate I got locally.

Tumbles · Mar 31, 2020

I've been messing around reversal development off and on for awhile now. I'm still experimenting, but I think this is my target:

Rodinal 1:10 with 2g Sodium Thiocyanate per liter for 15 minutes @ 20C with rotary agitation

I tried 1:10 at 20 minutes, and 1:5 at 15 minutes. Both were overkill, and they ended up looking faded where the blacks weren't as dark. They looked the same except the highlights were more blown out at 1:5.

I gave up on the light exposure part and went with a fogging developer since I think it was causing inconsistent results. I had to expose it to light underwater or else I would get water drops imprinted on the film.

Raghu Kuvempunagar · Apr 1, 2020

Tumbles said:
Rodinal 1:10 with 2g Sodium Thiocyanate per liter for 15 minutes @ 20C with rotary agitation

I tried 1:10 at 20 minutes, and 1:5 at 15 minutes. Both were overkill, and they ended up looking faded where the blacks weren't as dark.

With such a long developing time, Thiocyanate can do more harm than good. Have you tried lowering the concentration or even no Thiocyanate?

Tumbles · Apr 1, 2020

The highlights look fine with the run I did with 1:10 for 13 minutes. The mid tones look a bit on the dim side. Without Thiocyanate the frames looked really dark with dim highlights. It made a big difference.

Next I'm going to try the Ilford recipe with PQ Universal and Thiosulphate as a sanity check. Then I'll try 1:10 at 15 minutes if the Ilford recipe doesn't look dramatically better.

Raghu Kuvempunagar · Apr 1, 2020

Tumbles said:
The highlights look fine with the run I did with 1:10 for 13 minutes. The mid tones look a bit on the dim side. Without Thiocyanate the frames looked really dark with dim highlights. It made a big difference.

Next I'm going to try the Ilford recipe with PQ Universal and Thiosulphate as a sanity check. Then I'll try 1:10 at 15 minutes if the Ilford recipe doesn't look dramatically better.

Surely you need a more potent developer than Rodinal for reversal. BTW Ilford's recommendation for PQ Universal is 1+5 and not 1:10.

Agulliver · Apr 1, 2020

Acidified potassium dichromate is the best reversal bleach, but you're unlikely to be able to obtain it. The main issue with it and the permanganate based bleaches is not fumes but ingesting the solution. If you're mixing from scratch then you want to avoid inhaling the powders and be *extremely* cautious if you are using concentrated sulphuric acid - indeed I would advise against this unless you are laboratory trained. Additionally both the dichromate and permangante bleaches will stain clothes and temporarily stain skin if you spill any. They're not things you especially want on your skin either. Dichromate is somewhat carcinogenic and both are liable to irritate the skin and can cause allergic skin reactions.

Potassium dichromate may be banned from disposal down the drain in some areas. I do use it for 8mm reversal processing in my bathroom but I know what I'm doing, have access to laboratory chemicals (when I am at work!) and have checked with my water company about small quantities (I have 900ml max at one time). I mix my bleach at work in a laboratory using the correct procedures and glassware and take it home in an approved bottle.

Despite what I said about fumes not really being a problem, I wouldn't do darkroom work in an area that cannot be ventilated...just in case. Even B&W developer isn't exactly pleasant if you spill a cup full onto a carpet....it's not going to shorten your life but you want the smell gone. Other chemicals might potentially be a hazard to the lungs over long periods of time

Donald Qualls · Apr 1, 2020

mohmad khatab said:
Never heard this bleach before.
Did you try it yourself?
Generally speaking, it is very very cheap according to your recipe, but it will only last for one negative, I think.

I haven't yet tried it myself; as I noted, I've seen it done on video on YouTube. Joe van Cleave has several videos where he uses it after getting used to Harman Direct Positive, and then having it discontinued. There are multiple other videos, as well; some using citric acid, some acetic (easier to obtain, as white vinegar at 5% strength, in any grocery store).

NedL said:
Wish PE or Jerry Koch were still here to chime in, but I've stayed away from mixing hydrogen peroxide and acetic acid due to the possibility of forming paracetic acid.

I suspect that it's either peracetic acid or monopercitric acid that's doing the actual bleaching work in a peroxide bleach system. However, with a two-bath setup, you'll only have as much acid in the peroxide (or peroxide in the acid) as carries over in the film and reels, so the amount of any highly irritant substances that forms would be small. I think those who mix the acid and peroxide, as far as I've seen, have only used citric acid.

Tumbles said:
I gave up on the light exposure part and went with a fogging developer since I think it was causing inconsistent results. I had to expose it to light underwater or else I would get water drops imprinted on the film.

That suggests you weren't exposing enough. Originally, I recall Kodak calling out something huge, like 800 ft/candle seconds (that'd be minutes under an enlarger, for instance). You need to have the undeveloped halide fully exposed, since you want to develop all of it. Nothing says you can't use a fogging bath (sodium dithionite, for instance, commercially sold as Iron-Out) or a toner that reacts with halide (sulfur/sepia toner or nearly any color toner). The last time I did B&W reversal, I had 35 mm film on a steel reel; I pulled it out of the reel without disengaging the center clip, in good room light, exposed each side for about thirty seconds, rolled it back into the reel, and proceeded to second development I was very pleased with the results, aside from the gray base on Tri-X.

138S · Apr 1, 2020

EASmithV said:
I think I'm going to try a 1:25 or 1:50 dilution Rodinal for the development

Bare Rodinal may not be suitable, you need a more energic developer, if not you DMin will be to high, follow recipes known to work well for a certain film-development combination, you may refined recipes from BW cinematographers.

Basicly you want a high DMax and a low DMin, with a contrast that more or less follows what Provia or Ektachrome does. Adjusting a reversal process for a given film requires a remarkable effort.

One thing is making an slide to be scanned and corrected in Photoshop and another thing is making an slide that is beutiful when projected.

Let me recommend you to start with clear FOMA 100R and its reversal kit, it will work at the first try, so you will have an easy start to get proactice.

EASmithV said:
dichromate

dichromate is a hazard, if you use it... before disposal mix it with used developer, it will change from orange to green, to a way less toxic state.

dichromate has some advantage over permanganate, but the last is safer. A problem with permanganate is that when mixed it has a very short shelf life, so you mix what you are to use.

mohmad khatab · Apr 1, 2020

Donald Qualls said:
I haven't yet tried it myself; as I noted, I've seen it done on video on YouTube. Joe van Cleave has several videos where he uses it after getting used to Harman Direct Positive, and then having it discontinued. There are multiple other videos, as well; some using citric acid, some acetic (easier to obtain, as white vinegar at 5% strength, in any grocery store).

I suspect that it's either peracetic acid or monopercitric acid that's doing the actual bleaching work in a peroxide bleach system. However, with a two-bath setup, you'll only have as much acid in the peroxide (or peroxide in the acid) as carries over in the film and reels, so the amount of any highly irritant substances that forms would be small. I think those who mix the acid and peroxide, as far as I've seen, have only used citric acid.

That suggests you weren't exposing enough. Originally, I recall Kodak calling out something huge, like 800 ft/candle seconds (that'd be minutes under an enlarger, for instance). You need to have the undeveloped halide fully exposed, since you want to develop all of it. Nothing says you can't use a fogging bath (sodium dithionite, for instance, commercially sold as Iron-Out) or a toner that reacts with halide (sulfur/sepia toner or nearly any color toner). The last time I did B&W reversal, I had 35 mm film on a steel reel; I pulled it out of the reel without disengaging the center clip, in good room light, exposed each side for about thirty seconds, rolled it back into the reel, and proceeded to second development I was very pleased with the results, aside from the gray base on Tri-X.

Trust me ,,
The copper bleach that I told you about will work in a very comfortable way, without any problems at all, and it will live with you for a long period of time, maybe a year.
I advise you to bring anhydrous copper sulfate as it is considered the purest class of copper sulfate. + Sodium chloride (iodine stripped), + deionized water ,, if you want bleach to be fast, you must put 5ml sulfuric acid 37%. If you do not welcome sulfuric acid, there is no problem. It can be ignored, but the time must increase.
The temperature of the bleaching solution should be 40 degrees and not less than 8 minutes. If you remove sulfuric acid from the equation, the time should be at least 14 minutes with constant stirring.
Note: You do not add any ammonia to this solution at all, as this may cause the removal of the whole latent image (according to what the late Mr. Ron Maory told me as I remember.
- There should be absolutely no ammonia or bromide products in any bleaching solution in that particular process,
The copper bleach of process (C41) is a solution with a different composition with sodium bromide and possibly ammonium chloride, and potassium alum perhaps, but this is because it works within the process (C41), but in that process the matter is completely different. I hope you take notice.

Donald Qualls · Apr 2, 2020

I'm just getting back into the darkroom after twelve years (don't even have a darkroom yet, will have by summer, though). I'm going to try the peroxide bleach and look at ferricyanide for color processes before I return to sulfate bleaches. Even if you don't add sulfuric acid, the bleach solution will get pretty acidic, and copper sulfate is about as toxic as potassium permanganate (less so than potassium dichromate, however). If peroxide doesn't tear up the emulsion, I'll probably stick with that for B&W reversal, especially since it works equally well for paper direct positives as for film. I can buy 3% peroxide locally, for under a dollar a liter, and white vinegar for about the same price. Citric acid powder is easy to get and cheap to ship. If I find I have to have stronger peroxide, I can get up to 35% online, shipped to my door (probably with hazmat shipping, though, so cheap to buy, expensive to get).

removed account4 · Apr 2, 2020

Donald Qualls said:
I'm going to try the peroxide bleach

you might not look back after you use that ...

138S · Apr 2, 2020

Donald Qualls said:
then thirty seconds in the acid bath and 2-3 minutes in the peroxide (at this point, you can work in the light,

You may also make the bleach bath lights open, after you stop development no halide will developed. I'm doing it like this becuase I see when metallic silver has been enterily removed so I can adjust bleach time to least necessary, so halides won't be damaged (in some fine grain films). Also we may see when silver claering time gets longer because bleach bath is exhausted.

Donald Qualls · Apr 2, 2020

138S said:
You may also make the bleach bath lights open, after you stop development no halide will developed. I'm doing it like this becuase I see when metallic silver has been enterily removed so I can adjust bleach time to least necessary, so halides won't be damaged (in some fine grain films). Also we may see when silver claering time gets longer because bleach bath is exhausted.

Yes, exactly.

Also, back when I first did B&W reversal, I had the idea to do a "brightness control" bath, in the light, in a black tray, with very weak fixer to very slowly/gently thin the halide to lighten the final image. Not really practical with paper (because the halide is almost invisible on the paper base), but it avoids the need to heavily overexpose like a lot of the paper direct positive videos show. Even without that, I saw a slight speed increase with Tri-X (of fifteen years ago, near enough) when processed for reversal. Somewhere here I have the developers I used...

138S · Apr 2, 2020

Donald Qualls said:
with very weak fixer to very slowly/gently thin the halide to lighten the final image.

Yes... BW slides are complex to adjust, this is not like negatives, one has to nail the result. That weak fixer lightens the image solving DMin, but it also lowers DMax... Another way would be using a more energic developer that is able to develop all silver in the extreme highlights...

Donald Qualls · Apr 2, 2020

Yep, that would probably be better. That was just an idea I had for "develop by inspection" adjustment, and would require an experienced eye, like any DBI process.

Wanting to try reversal processing but also not die

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