Reversal processing: image tone

Hans Borjes · Mar 25, 2006

I am asking myself what ways are existing to marginally influence the image tone of b/w slides without nasty effects like split toning.

According to my taste, looking back to my last Scala slides, they are the reference and have a most pleasant image tone.

Light-reversing FP4 in Rodinal is already a big achievement over TMAX in the Kodak kit. However, the image tone is still cooler than Scala and in direct comparison it seems worth to think about closing that gap.

I have not tried potassium dichromate bleach, but is there a change in image tone compared with potassium permanganate?

Are there harmless chemicals I could add to the second developer to change the image tone? I even wonder what happened when I added 2ml of selenium toner to the second developer?

Alicouscous · Mar 25, 2006

You can use thiocarbamide with sodium hydroxyde as a fogging agent . If you change the ratio thio/hydro you can change the final image tone .

Jordan · Mar 25, 2006

Your final processed film can be chemically treated as you would a print -- theoretically, you could bleach-and-redevelop (with a sepia toner kit), do direct-toning (with Viradon or Kodak Brown Toner or something like that) or selenium tone your positives. I have no idea what times/concentrations to start with for any of these, though. The effects on image tone may be different than what you get with prints.

I seem to remember reading some speculation that Agfa included a selenium toning step as part of the Scala process. This may be worth trying first.

Tom A · Mar 26, 2006

Hi

For my reversal process, I use paper developer which comes with different tones, warm, neutral and cool.

For most of my processing, I have used Tetenals Variospeed W, which gives the slides a warme tone, which differes from filmtype to filmtype. I have just started to use Tetenals Eukobrom (have only made a couple for test developments), this developer gives FP4+ a nice neutral tone.

Hope this helps you or gives you some inspiration.

Tom

Hans Borjes · Mar 26, 2006

Alessandro Serrao said:
In what direction?

From yellow-green (with the emphasis on green) to a more neutral tone.

Hans Borjes · Mar 26, 2006

Alicouscous said:
You can use thiocarbamide with sodium hydroxyde as a fogging agent . If you change the ratio thio/hydro you can change the final image tone .

It seems to me that sodium hydroxide is contained in sewage disposal cleaner. How about thiocarbamide, how harmful is that?

I would be interested in more detailed info regarding creation of that fogging agent, concentration, processing time, etc.

David A. Goldfarb · Mar 26, 2006

For many print emulsions, selenium toning will turn prints from greenish to neutral. I'd try that.

David A. Goldfarb · Mar 26, 2006

Alessandro Serrao said:
But a print emulsion is not like a film emulsion: thus the outcome would be unpredictable.

True, but it would be an easy test to run, and most B&W printers have selenium toner on hand, and selenium toning of film is fairly common for intensification and archival purposes, so we know it will do something.

Hans Borjes · Mar 28, 2006

I have been continuing to experiment with light reversal, and I have found that it is possible to do an even fogging exposure of FP4 120 film with a relatively high amount of light (100W, 40cm, 2x3min), but: the entire film now shows a yellow image tone. I have increased the time for the first developer already to compensate for the density, but I have the feeling that this yellow tone could be related to remains of sulphur from the sodium metabisulphite clearing bath that gets "burned" into the emulsion by the light?

Is that a known effect that a yellow curtain is created by light reversal?

Gerald Koch · Mar 29, 2006

A 2% solution of sodium sulfide can be used as a fogging second developer. This is Kodak T-19 and produces a sepia image. You can also use sodium hydrosulfite (sodium dithionite Na2S2O4). This is used in Kodak FD-70 and FD-72. IIRC these formulas produce a black image.

Hans Borjes · Mar 29, 2006

Alessandro Serrao said:
Maybe you should carry the steps from mid-bleaching on in daylight so you can check the clearing time (could be also that, due to the increased area of 120 with respect to 35mm, you should increase the strenght or the clearing time).

The film is very white during second exposure. I once tried to re-use the clearing bath as suggested by the recipe of Kai Rechtenbach, but found the film to be very yellow (just like the clearing bath itself a few days after first use). Since then I make single use of the clearing bath.

Alessandro Serrao said:
Are you fully washing the film between each steps?

I have increased the number of rinse steps to 4x30sec after the bleach from 2x30sec at the beginning; the rinse water is clear at the fourth rinse step. However, rinse after clearing bath is only 2x30sec - this is maybe not enough, I have once noticed that the exposure bath is slightly acidic, as indicated by some prickling on my thumb.

Gerald Koch said:
A 2% solution of sodium sulfide can be used as a fogging second developer. This is Kodak T-19 and produces a sepia image. You can also use sodium hydrosulfite (sodium dithionite Na2S2O4). This is used in Kodak FD-70 and FD-72. IIRC these formulas produce a black image.

Thanks for the info, I will Google a little bit for it. Have you tried one of these formulas?

Gerald Koch · Mar 30, 2006

Sodium hydrosulfite was used in Kodak's reversal kit and I have used that in the past. I have not had any problems in the past with either sodium sulfide or sodium hydrosulfite. Modern emulsions are quite robust. However, I would suggest testing the film that you are using first.

Hans Borjes · Mar 30, 2006

Gerald Koch said:
Sodium hydrosulfite was used in Kodak's reversal kit and I have used that in the past. I have not had any problems in the past with either sodium sulfide or sodium hydrosulfite. Modern emulsions are quite robust. However, I would suggest testing the film that you are using first.

Hmm, does that mean you simply added the sodium (hydro)sulfi(d/t)e to the second developer? Or, solved it in water to have a fogging agent without any other additional substances? Can you share in detail what you did, which concentration, which processing time at which temperature?

I am so interested in the details because I am not enough chemically skilled to calculate myself how chemistry will interact.

Gerald Koch · Mar 30, 2006

No the sodium hydrosulfite is the second developer. The following is what Kodak supplied in their reversal kits. Despite the name thiobarbituric acid is not a narcotic. The role of the thiobarbituric acid and the cysteine is to clean up the highlights.

Kodak FD-70

Stock Solution A

Distilled water ....................... 750 ml
Sodium hydrosulfite .................... 5.0 g
Distilled water to make ................ 1.0 l
Stock Solution B

Distilled water ....................... 750 ml
Sodium metaborate ...................... 10.0 g
2-Thiobarbituric acid .................. 0.5 g
Distilled water to make ................ 1.0 l

Usage

For use mix equal parts of A and B. Use within two hours of mixing. Discard the working solution after use.

Another fogging developer

Kodak FD-72

Distilled water ....................... 750 ml
Sodium metaborate ...................... 10.0 g
L-(+)Cysteine HCl ...................... 0.3 g
Distilled water to make ................ 1.0 l

Usage

Just before use add 5 grams of sodium hydrosulfite to the above solution. Use within two hours of mixing. Discard the working solution after use.

Hans Borjes · Mar 31, 2006

Gerald Koch said:
Kodak FD-70 ...
Kodak FD-72 ...

Well, these formulas can be seen on various places of the web already. I was asking specifically what you are using. Without processing time and temperature, I assume you don't use this formula?

Hans Borjes · Mar 31, 2006

Alessandro Serrao said:
However to cut a long story short I've found that a concentration of 0.5% sulfide is quite sufficient provided the film is treated no more than 3 or 4 minutes...

In your process you describe "Secondo sviluppo: in solfuro di sodio 20g/500ml (30ml) per 3 minuti, 1 inversione di 5 secondi ogni 15 secondi".

So, 20g/500ml is for the stock solution? How do you dilute 30ml to make a working strength solution? Temperature is the same as for your first developer (20°C)?

Gerald Koch · Mar 31, 2006

Alessandro Serrao said:
Gerald,
the formula where it says 20g sodium sulfide in 1 liter of water refers to the "cine" reversal film processing, not the kind we are using (35mm or 120).
The "cine" film are hardened more at production while the "normal" counterparts are not (except T-Max).

Believe me, I've tried a 2% concentration of sodium sulfide and it just peel off any emulsion from the triacetate base of almost any film (T-Max is a little tougher than the rest).

However to cut a long story short I've found that a concentration of 0.5% sulfide is quite sufficient provided the film is treated no more than 3 or 4 minutes...

Thanks for that information. It has been many years since I did any reversal processing.

Gerald Koch · Mar 31, 2006

Hans Borjes said:
I was asking specifically what you are using. Without processing time and temperature, I assume you don't use this formula?

I have used FD-70 but it was so long ago that any film specific information would no longer be relevent.

There is a cleaning product called Pro Rust Out which contains sodium hydrosulfite and sodium metabisulfite. It is used to remove rust stains in fabrics. It is a powder with a strong sulfurous odor. I have always wanted to try it as a developer. If you have difficulty in finding sodium hydrosulfite you might give it a try. I think it's roughly equal parts of each chemical. You would have to neutralize the acidity of the metabisulfite. You can get it in grocery and hardware stores and it is not expensive, comes in a 1.5 lb container.

Hans Borjes · Apr 28, 2006

Hans Borjes said:
I have been continuing to experiment with light reversal, and I have found that it is possible to do an even fogging exposure of FP4 120 film with a relatively high amount of light (100W, 40cm, 2x3min), but: the entire film now shows a yellow image tone. I have increased the time for the first developer already to compensate for the density, but I have the feeling that this yellow tone could be related to remains of sulphur from the sodium metabisulphite clearing bath that gets "burned" into the emulsion by the light?

Is that a known effect that a yellow curtain is created by light reversal?

We have now the evidence that at least in the Foma reversal process with 2 subsequently processed Fomapan R100, less second exposure resulted in less yellow intensity. However from my experiments with FP4 and Rodinal I know that further reducing the second exposure results in yellow curtains, that appear on the heavier fogged parts of the film only.

But the good news is that by replacing the second exposure with a stannous chloride solution in potassium hydroxide, this yellow effect is completely gone, i.e. fogging has become controllable.

Hans Borjes · Apr 28, 2006

Alessandro Serrao said:
The Foma kit says to use the same solution as a first and second developer. It means that Foma doesn't put any halide solvent in the first developer so as to reuse it as the second one.

Try to use the first Foma developer with any halide solvent and just prepare a fresh second developer withou the halide solvent.

It can solve your problem.

This would be quite a logical explanation why Ilford recommends to add sodium thiosulphate to the first developer. Why don't they point out what it is good for, if that's used to prevent the yellow effect?

We intend to run a test reversal with Tetenal Eukobrom and FP4 tomorrow. Do you have experience with that developer/film combination? BTW, we will be running 24°C.

There is also another color phenomenon, that I could not get rid of so far. As opposed to my friend's experiments in the Foma kit, I was running Rodinal and first had to fiddle with the same yellow cast as in Foma. Now, even with stannous chloride fogging, in my custom process I cannot get rid of a brown tone. I guess that is because of the potassium permanganate solution's brownstone that gets into the emulsion? We have bought digiscales now to be able to create a fresh bleach for every film being processed. Hopefully that will create the same neutral result with chemical fogging as with Foma, where potassium permanganate also comes in small portions.

Hans Borjes · Apr 28, 2006

Alessandro Serrao said:
I would strongly suggest to avoid running the reversal process to 24°C, especially if you use a permanganate based bleach.
Infact permanganate, although being less toxic, has some disadvantages over the dichromate because it softens the gelatine (in reality it's not the permanganate that softens the gelatine per-se, it's the huge shift between a highly alkaline solution of the first developer and the highly acidic bleach).

I'd suggest to use a temperature between 18°C and 20°C maximum and be sure to have all solutions (including the washing steps) at THE VERY SAME temperature, and I means with no more than 0,3°C worth of difference (much the same as in E6 process).

The water in my Jobo CPE-2+ reaches a temperature of 21°C already when left at room temperature, even with the heating turned off. So I guess I would not be able to use the thermostatic feature of the machine when running the process at 20°C.

As I started my reversals with the Kodak kit, I chose 24°C and find it quite convenient. When I started implementing my own process based on the Rodinal recipe published by Kai Rechtenbach, I stayed on that temperature. I shortened the bleaching time to 2 minutes at 75rpm, 10ml of 38% sulphuric acid to 250ml destilled water, and very important: only 250mg potassium permanganate per film. 500mg as documented by Ilford or Foma will indeed kill the emulsion at 24°C, I have tried that.

With the less concentrated bleach even Ilford FP4 survives that without any damage when 5ml Tetenal hardener is added to the fixer. This is the only stage where I use hardener.

I wonder how we can 'guesstimate' FP4 times in Eukobrom from your data.

Hans Borjes · Apr 29, 2006

Alessandro Serrao said:
This is extremely interesting: I've never tried halving the permanganate concentration. Maybe your problems for yellow-cream image residues (which leads to image fogging) can derive from underbleaching that way?

I don't think so for the following reasons:

The Foma process shows the same yellow coloration with (and dependent on the intensity of) light exposure, and it uses 500mg potassium permanganate for 5 minutes at 20°C. More than enough bleaching. The coloration disappears there with chemical fogging.
The Rodinal process inherited from Rechtenbach also shows the coloration only with strong second exposure. By reduction of second exposure intensity I got the yellow coloration on the beginning and end of the film only; exactly the inner and outer windings on the reel where second exposure intensity is stronger by nature. Some few slides in the middle of the film that were shaded by the inner and outer windings are perfectly fine. The borderline of the yellow coloration was exactly matching the physical placement of film on the reel.

Hans Borjes · Apr 29, 2006

Alessandro Serrao said:
I'm just keep asking myself a thing: with the demise of Agfa, could one get his hands on Scala chemicals???

It would actually be very desirable that A&O Agfa adds to its portfolio of Rodinal and other chemicals a reversal chemistry set and a matching reversal process where all parts can be purchased separately. This is the common fault of the Foma and Kodak reversal process: you have to discard unused chemicals. In the Foma process the bottleneck is the first developer that cannot be stored long enough once the package was opened, in the Kodak process it is the bleach stock solution that gets oxidised.

Even under perfect conditions the results with both kits are not satisfactory:

Foma has this yellow coloration or uneven second exposure as long as the film is not removed from the reel or chemical fogged by own chemistry.
Kodak documents first developer times that by now way deliver comparable results with the density and contrast of Scala. Of course this can be easily adjusted by the user, but it is impossible to get rid of the too strong green cast without stealing brightness by brown toning.

Reversal processing: image tone

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