Alternative "E-6" process using RA-4 developer

Osmdesat · Apr 20, 2024

I'm working on my own alternative color reversal process for developing E-6 films. Idea behind is to avoid expensive E-6 kit or expensive lab processing, while being as simple as possible.
For my experiments I use some ready-made BW positive high-contrast developer Foma GD-L as first developer, homemade RA-4 developer as color developer (formula from Bonavolta), homemade ferricyanide bleach and ready-made rapid fixer. Reexposure is done with light.
Film used is Kodak Ektachrome E100.
After some initial fails (pictures almost black) I came to results which already show some color image, but with heavy orange cast, see photos.

I used this process:
0. Exposure in camera (accidentaly exposed at 200ASA)
1. Foma GD-L developer solution 1+4 with 2g potassium thiocyanate per litre - 6 min. at 40°C
2. Wash with lukewarm water - 2 min
~~3. Reexposure under 100W bulb in cca 10cm distance - 5 min~~
3. Reexposure under 11W 4000K LED bulb in cca 10cm distance - 3 min
4. RA-4 color developer (Bonavolta formula) - 6 min at 40°C
5. Wash with lukewarm water - 2 min
6. Ferricyanide bleacher - 5 min at 40°C
7. Wash with lukewarm water - 2 min
8. Rapid fixer - 3 min at 40°C
9. Wash with lukewarm water

In the images we can see heavy orange cast/fog. This cast is also present at the film tail, which was heavily exposed with daylight - see pic.
Question is what to do to be fog-free.
In the exposed tail is visible, that the cast is not uniform and is less near the edges of the film and in the middle is stronger. This suggests that maybe agitation during 1st development was insufficient - I used agitation 10sec every minute, which is maybe too little as in reversal development the reaction is much stronger than at negative development.
But I feel that even at stronger agitation the cast will probably still be there.

I am unable to isolate the problem. Do I need longer 1st development? More thiocyanate? Unsuitable formulation of the 1st developer? More light? Or do I need something to do with color dev? For instance Kodak recipe puts thiocyanate also into color dev...

Rudeofus · Apr 21, 2024

Before I delve into the thicket of E-6 processing: if you want anyone to debug your process, then please don't start with some oddball product as first developer. We can vaguely guess, which this "Foma GD-L" thing does and have no idea, how it is formulated. Please start with some powerful B&W film developer (the real E-6 FD is extremely powerful) or paper developer, ideally a well known product.

Back to E-6: if your highlights don't turn out mostly transparent, then most likely your FD soup is too weak. Raise its pH, add more thiocyanate, use higher concentration - do something! - to make it more active. Once you have black shadows and white highlights, we can take a closer look at colors.

PS: the film leader of E-6 film is notoriously bad for judging highlights. There is some effect, in which excessive exposure leads to less developability, so it's quite common, that the film leader is denser than the highlights of my images. It's also anything but uniform, so don't waste time on agitation experiments until you have black shadows and white highlights.

koraks · Apr 21, 2024

@Osmdesat great to see you here, welcome aboard!

I'm not of much help, but the picture of the leader suggests that the fogging exposure may not be sufficient. I see 'flames' of lower density extending from the top and bottom of the film, which I would expect with the film on a reel and the light somehow not penetrating the emulsion across the entire film surface. An 11W bulb isn't that super bright (even with LED); maybe something brighter and/or longer exposure would help. Personally, I'd be inclined to try a chemical means of fogging instead so that the geometry of the reels and the spiral of the film casting a shadow onto itself ceases to be a problem.

Rudeofus said:
We can vaguely guess, which this "Foma GD-L" thing does

In principle I agree with your comment and I had to Google as well. But this is what it turns up: https://www.foma.cz/fr/fomagdl
Apparently it's a PQ developer for line art, so I expect it's a high-activity developer and might in fact be quite an appropriate choice.

Rudeofus · Apr 21, 2024

koraks said:
An 11W bulb isn't that super bright (even with LED); maybe something brighter and/or longer exposure would help.

If the reexposure is incomplete, then he still gets white whites, it's just the shadows which suffer from bad reexposure.

koraks said:
In principle I agree with your comment and I had to Google as well. But this is what it turns up: https://www.foma.cz/fr/fomagdl
Apparently it's a PQ developer for line art, so I expect it's a high-activity developer and might in fact be quite an appropriate choice.

It may be a good chance, but I can't remember anyone using it, and we don't know its formula. This is very different from e.g. Dektol, which some people have used and which can easily be compared to Watkin's E-6 FD formula. People have tried Rodinal and posted results. Rodinal will not be easy to compare to Watkin's E-6 FD, but it's such a universally available developer, that it has been tried by many before, so there's at least a body of knowledge. People have had some success with HC-110. HC-110 is another such developer, which almost everybody has used at some point in time.

Osmdesat · Apr 21, 2024

Thank you guys for your replies and thoughts. Here is further explanation to the issues you mentioned:

First developer Foma GD-L, as Koraks found, is Phenidone-Hydroquinone based, high contrast very active concentrated developer, suitable also for print materials. The developer is known for producing high contrast paper prints with very deep blacks, so I decided to test it in BW reversal process, although not yet with definitive results. But even without thiocyanate it gave decent results. The developer is affordable and here in Czechia widely available, since it's Foma product. But I cannot tell anything about its formula or even whether it's a clone of some big K's formula.
Reexposure was made by directly shining onto the surface of the film, removed from the tank reel. However during my last test I realized that in my previous tests I shone onto emulsion side of the film only. So I got suspicious that deeper layers of the film were illuminated unsufficiently. So in my last test I shone on both sides of the film. But it didn't prove to be a cause of the orange fog, as I'll explain later.

Today I did another two tests, with changes concerning BW stage of the process.

In the first test I increased the concentration of the First developer (Foma GD-L solution 1:2, 40°C, 6 min, thiocyanate 1g/l added). Other steps remained the same. However the film came out similar to the previous test, where the concentration was only 1:4. Similar overall density, similar orange fog everywhere.

In the second test the concentration of Foma GD-L was again 1:2, but thiocyanate of amount 5g/l was added. The other parameters of the process remained the same. The images in the film appear burnt out, with lost drawing in highlights and midtones, only with a hint of shadows. The unexposed areas which should be black came out as dark orange. However everything is covered with a strong fog again, though not orange anymore, but rather magenta.
It looks like the overdose of thiocyanate caused the extreme brightening of the image, which suggests that BW stage works fine. However even then the film is covered with a colour fog. So it seems to me that something is wrong in colour stage.
I have two ideas - the color developer is maybe wrong. Or can it be that wrong stopping can cause the color fog? I use only water stop. Maybe I should use acid stop...
The resulting images from the second test are attached. Again the flower box, which was exposed quite darkly, so it show at least something. Other two open space scenes are almost burnt out (but with magenta fog). And again the exposed leader and beginning of the frame.
All the images posted are taken in RGB LED backlight set for neutral white.

Osmdesat · Apr 27, 2024

In next test I used as 1st developer 1+3 solution of Foma GD-L w. 1g per Litre of thiocyanate.
Because I vaguely remember reading somewhere that lack of proper stop bath can also cause color fogging, I tried to mix proper stop bath in this iteration.
I used stop bath consisting of 1% acetic acid after 1st and 2nd developer. Other parameters stayed the same.
The result is in the attachments. Color cast is pretty away, however some hint of orange fog is still there. But even now the images start to be quite usable. I reckon that due to usage of substitute developers, color saturation and purity is gonna be compromised, and probably some crossover will be induced, but this doesn't necessarily need to be a bother for me. We can embrace the imperfections if we like them.
Of course I must verify if the lack of acid stop bath was the cause of orange fog, or if it was only a coincidence (for example RA-4 developer I mixed is now one week old, so it could change its characteristics).
Question is if 1% acetic acid is enough. Maybe I should use 2%, as is recommended in BW positive materials. E-6 recipe for stop bath reads 6ml acetic acid and 30g sodium acetate for 1 litre water.
I also didn't come to definite conclusion how much of thiocyanate should I use in 1st developer.
And do you know the purpose of thiocyanate in 2nd color developer - recipe mentions 1,3 g per litre.

koraks · Apr 28, 2024

Osmdesat said:
Question is if 1% acetic acid is enough.

I'd be inclined to give it a try with a stronger acid; e.g. 1% sulfuric acid instead of acetic. Note that in ECN2 processing, sulfuric acid is also prescribed, and Photo Engineer has hinted several times on the importance of a strong acid stop bath as opposed to a weak acid. Perhaps in your experimental process this difference is even more relevant than in regular processing.

The difference with the stop bath is remarkable!

Rudeofus · Apr 28, 2024

Osmdesat said:
Because I vaguely remember reading somewhere that lack of proper stop bath can also cause color fogging, I tried to mix proper stop bath in this iteration.

Proper E-6 process does not use a stop bath, but a thorough water wash between FD and the consecutive steps. Did you do that "thorough water wash" step after FD, before you reexposed the film?

@koraks if it turns out, that the weak/missing stop bath was indeed solely responsible for this massive orange cast (which I still doubt, although the now introduced stop bath may well cover up the lack of water wash), then a strongly buffered stop bath will be more effective than a dilute low pH one. Bill Troop has some very effective suggestions in his Film Developing Cookbook.

koraks · Apr 28, 2024

Rudeofus said:
then a strongly buffered stop bath will be more effective than a dilute low pH one.

If you say so...Ron was always quite adamant about the matter. He never offered a mechanism for it, just stated it as fact that a strong acid stop bath (although dilute) would be more effective in pulling the developer out of the film. I'm not a chemist, so I can't argue.

Osmdesat · Apr 28, 2024

Rudeofus said:
Proper E-6 process does not use a stop bath, but a thorough water wash between FD and the consecutive steps. Did you do that "thorough water wash" step after FD, before you reexposed the film?

I meant unofficial E-6 recipe, sorry. Real E-6 doesn't use acid stop bath, you are right.
In real E-6 there's chemical fogging there, so maybe some residues of FD don't bother here.
Before re-exposure I did wash the film at least for 2 mins with water in my tank, shaking, with 3 exchanges of water. Maybe it was still not enough.
My theory is that after my waterwash there were still some remnants of FD in bottom layers of the film and they were still active during re-exposure.

lamerko · Apr 28, 2024

Also, PE offered the VNF-1 process as a basis for such non-standard attempts. There is a stop bath 3% acetic acid and some hydroxide for 30 seconds.

Osmdesat · Apr 28, 2024

lamerko said:
Also, PE offered the VNF-1 process as a basis for such non-standard attempts. There is a stop bath 3% acetic acid and some hydroxide for 30 seconds.

VNF-1 has an advantage of being publicly available, while E-6 is "secret". However count of chemicals in the formulas is really generous, with some obsure specialties like "Kodak Reversal Agent", which is discouraging.
Ferricyanide bleach with 5 compounds is just ridiculous. I am no chemistry freak, so not for me.
However stop bath there is interesting. Seems like Hydroxide acts here as "opposite" buffer?

Osmdesat · Apr 28, 2024

koraks said:
...Ron was always quite adamant about the matter. He never offered a mechanism for it, just stated it as fact that a strong acid stop bath (although dilute) would be more effective in pulling the developer out of the film. I'm not a chemist, so I can't argue.

I think acid stop bath simply pulls down pH, which stops developer developing, as developer needs high pH to develop. Mere water is not enough to quickly stop the developing and some development maybe continues during re-exposure, which causes my color cast.
I tried also 2% acetic acid in my further tests and it gave no difference against 1% acetic acid.
I will try sulphuric acid in next test.

Rudeofus · Apr 28, 2024

koraks said:
If you say so...Ron was always quite adamant about the matter. He never offered a mechanism for it, just stated it as fact that a strong acid stop bath (although dilute) would be more effective in pulling the developer out of the film. I'm not a chemist, so I can't argue.

There are two distinct issues, which will be addressed by different properties of a stop bath. If you just want to pull pH down to levels where development comes to a complete stop, then a buffered stop bath will be the right choice. If you want to clean out oxidized and potentially polymerized developer from your emulsion, then a strong but dilute acid will be the better choice. From looking at common process chemistry for E-6: the lowest pH encountered in the process chain is somewhat above 4, so any pH below that level will be at least "out of spec".

BTW I was wrong in my assessment, that carryover FD would trigger fogging in the CD step. If the FD worked correctly, there should be no developable silver halide left in strongly exposed areas, and formation of this dense orange colored fog should only be possible, if someone else oxidized the CD in the process. So either the FD did not do its job in your first test runs, or something oxidized the CD.

Ben Hutcherson · May 16, 2024

Osmdesat said:
VNF-1 has an advantage of being publicly available, while E-6 is "secret". However count of chemicals in the formulas is really generous, with some obsure specialties like "Kodak Reversal Agent", which is discouraging.
Ferricyanide bleach with 5 compounds is just ridiculous. I am no chemistry freak, so not for me.
However stop bath there is interesting. Seems like Hydroxide acts here as "opposite" buffer?

Mixing sodium hydroxide with acetic acid quite literally gives you the textbook definition of a buffer. The sodium hydroxide will react with the acetic acid to give sodium acetate, which mostly exists in its dissociated form in water as an acetate ion. Acetic acid, a weak acid, mixed with acetate ions, the conjugate base of acetic acid, most certainly will set up a buffer system.

With that said, the pH specified here of 3.5 is at the very edge of the buffering range of an acetate buffer. The usual rule of thumb is that a buffer is most effective when pH=pKa, and the buffering region is usually specified as +/-1 of the pKa. The pKa for acetic acid is 4.74.

Some back of the envelope math say that this solution would have an acetic acid concentration of about .48M and an acetate concentration of about .04M. Using the Henderson-Hasselbach equation, which is iffy with a 10-fold concentration difference between the two, gives a calculated pH of 3.66, which is not that far off from what recipe says the pH should be.

Just using 30mL of glacial acetic acid in 1L water would give a pH of about 2.5.

Here's the key that I see with this, though. This is a poor buffer in the sense that if you wanted to keep the pH from going lower, it would not be particularly resistant. With that said, it should keep the pH from RISING very much.

Given that the whole point of a stop bath is to decrease the pH of any carry-over developer, this seems almost a perfect solution for that purpose...

smclennan · Jun 2, 2024

Thanks @Osmdesat for this timely post. I had overlooked the strength of the stop bath in the ECP2 recipes and, using water or water with a splash of vinegar, was getting monochrome colour. Your sample images going from orange monochrome to full colour were literally an eye opener. I then used 300ml grocery store vinegar (5% acetic acid) in 1L so a 1.5% solution and got a variation in colours (not necessarily “realistic”).
By the way, context is Kodak 3383 print stock (16mm) shot in camera. As you said: “we can embrace the imperfections if we like them”. Experimental filmmaking, indeed. Back on track here. Merci.
PS, I did a Double 8mm Fomapan shoot/process/project workshop at the university in Ústi nad Labem and much enjoyed my time in Czechia

Sonynolta User · Jun 4, 2024

Just a guess here... I wonder if the color cast is due to the LED bulb for reexposure. Depending on the bulb, if it is not a high CRI, it may have 'holes' in the spectrum, and may not be re-exposing all the colors evenly / enough. People often post on reddit why their RA4 darkroom prints are uncorrectable of a hideous color, and it usually boils down to using some cheapo LED bulb in their enlarger.

koraks · Jun 4, 2024

Sonynolta User said:
People often post on reddit why their RA4 darkroom prints are uncorrectable of a hideous color, and it usually boils down to using some cheapo LED bulb in their enlarger.

Meh.
Meh meh.

I'm taking a WAG and contend that in 95% of the cases it's just people struggling with the basics of color balancing. It's a skill that has to be learned. But it's of course very convenient for all involved if the LED bulb pops up and "aahhhh, there you go, that must be it" and nobody loses face in the process...

Osmdesat · Jun 4, 2024

@smclennan Nice to hear you visited Czechia for film shooting. I have also done some experiments with Fomapan R motion film, but they are suspended for now. But I plan to come back to motion film since time allows.
To the problem with the color cast - the images were not monochrome, just the color cast was so strong that the colours got drowned. According to my recent knowledge, the colour cast was in my case caused perhaps by missing acid stop after the colour (second) developer. In my last test I forgot to use stop bath after color developer (I did use it after 1st dev however) and color cast came out the same as in my first attempt posted. To verify it, I should probably omit acid stop after 1st dev and use it after color dev. I must resume my experiments as soon as possible. I must find out exact time and temperature of first dev for box speed and times for push, too, because slide film pushes very willingly, so why not to use it.

Sonynolta User said:
Just a guess here... I wonder if the color cast is due to the LED bulb for reexposure. Depending on the bulb, if it is not a high CRI, it may have 'holes' in the spectrum, and may not be re-exposing all the colors evenly / enough. People often post on reddit why their RA4 darkroom prints are uncorrectable of a hideous color, and it usually boils down to using some cheapo LED bulb in their enlarger.

My LED bulb was CRI 90, I don't use anything lower in my house. I chose LED for higher color temperature. With incadescent bulb I had problem with blue cast due to insufficient reexposure of blue-sensitive layer. Yes, I can fry the film (and myself) with 500W halogen floodlight, but high kelvin LED is IMO much more efficient for reexposure, needing only fraction of watts for full fogging.

Sonynolta User · Jun 4, 2024

koraks said:
Meh.
Meh meh.

I'm taking a WAG and contend that in 95% of the cases it's just people struggling with the basics of color balancing. It's a skill that has to be learned. But it's of course very convenient for all involved if the LED bulb pops up and "aahhhh, there you go, that must be it" and nobody loses face in the process...

Sorry I tried to help. Maybe I'll avoid that in the future.
But sometimes people don't always have years of experience or someone to help that grew up with this stuff. You see that a lot on reddit. It can be a goofy place, but it's where people are. Turns out, you put a blue daylight-ish bulb in a color head, and it will be difficult to correct out that blue. Another example is the time some poor noob couldn't figure out why all her prints from a Jobo drum were strangely fogged with orange streaks. Got all kinds of advice about needing new chemistry or paper. Turned out she was using a film cap with the open funnel, and didn't have a cup cap.
Sometimes the simple solutions are just that.

Sonynolta User · Jun 4, 2024

Osmdesat said:
....

My LED bulb was CRI 90, I don't use anything lower in my house. I chose LED for higher color temperature. With incadescent bulb I had problem with blue cast due to insufficient reexposure of blue-sensitive layer. Yes, I can fry the film (and myself) with 500W halogen floodlight, but high kelvin LED is IMO much more efficient for reexposure, needing only fraction of watts for full fogging.

Ok. Good to see you eliminated that possibility. Glass lightbulbs are not always friendly to environments with liquids.

I was in Czechia for vacation last summer. Drove in by bus, and got to see Chesky Krumlov and Prague. Very beautiful cities, towns and countryside. I'd like to go back sometime, very beautiful country you've got there. The art deco buildings in Prague are stunning (Much better than my experiences with with Foma 400 - haha) I've got some R100 I'm going to try reversal with soon.

Osmdesat · Jun 4, 2024

@Sonynolta User I am glad you liked it here. Next time you visit us, try some non-tourism regions and towns. You will relax more and your pocket will get less ransacked, too ( ; Prague and Český Krumlov are fine, but massive tourism there spoils the experience.

Yeah, I just happen to shoot Fomapan 400 now ( : It's not very perfect, but it's plain old-style film, which is fine for me. In meterware it's very cheap. I can enjoy shooting it without bad feeling of wasting too much money.

koraks · Jun 4, 2024

Sonynolta User said:
Sometimes the simple solutions are just that.

I agree that sometimes, problems track down to fairly basic/simple things. Good thing, too -makes them easier to solve! I also acknowledge that Reddit in particular attracts a lot of newcomers to darkroom work, which is great - but not all that many experienced printers seem to contribute, at least in the threads I've seen over the years. That makes it sometimes a bit of a 'funny' place in terms of troubleshooting. I've considered chiming in, but I focus my energies.

And sorry to pick on your comment the way I did. It's just that I have a really hard time believing that a white LED bulb, even a poor one, will make prints uncorrectable. I've done a lot of work on RA4 paper and the one thing it really doesn't care about, is discontinuous light sources. The filter settings may (will) have to be different, and you may end up with subtle differences compared to a tungsten bulb, but it'll print OK in the end. Using something like a 5000K LED bulb in an enlarger will definitely throw off your blue/yellow filtration by a mile - but it just means you end up with a kind of weird filter setting relative to an old-fashiioned bulb.

Concerning the re-exposure - you may have a point, but again, given sufficient exposure, you'll hit the peaks of all three layers even if you use a poor white bulb. There may be odd stuff going on if you (a) use a discontinuous light source with a very unfortunate spectrum (nothing real-world comes to mind though) and (b) the re-exposure is on the verge to begin with.

MattKing · Jun 4, 2024

Just a caution here.
CRI is a very poor indicator of how appropriate a light source might be for these things.
It is oriented to human visual response, not the sort of response that film, paper or sensors have to light.
There are standards that are much more accurate - the ones used by some in the motion picture industry being one example - but most easily accessible "bulbs" don't have test results respecting those standards associated with them.

Osmdesat · Jun 4, 2024

MattKing said:
Just a caution here.
CRI is a very poor indicator of how appropriate a light source might be for these things.
It is oriented to human visual response, not the sort of response that film, paper or sensors have to light.
There are standards that are much more accurate - the ones used by some in the motion picture industry being one example - but most easily accessible "bulbs" don't have test results respecting those standards associated with them.

That's right, in this case only cumulative energy hitting the three layers is decisive and the spectral distribution doesn't matter here. Important here is that only enough energy is delivered to all the three layers to get them fully exposed.

Alternative "E-6" process using RA-4 developer

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