B&W Reversal using a Chromogenic Process?

ChrisGalway · May 5, 2025

Has anyone tried B&W reversal processing using a chromogenic (black) dye process?

Might it offer any advantages (reduced grain?) or disadvantages? I note that Ilford XP2 for example uses a chromogenic process ... but it's a negative, not positive, process.

lamerko · May 5, 2025

For some reason they come out with a strong magenta tint...

Donald Qualls · May 5, 2025

XP2 Super is easy to reverse.

First, develop in any convenient B&W developer with a very little thiosulfate or thiocyanate added (this can be adjusted to get the final density you want).
Second, expose the film to light (still on the reel generally works) -- and give it lots of light, to be sure it's completely fogged.
Then run through a standard C-41 process. Result: slightly pink B&W slides. Shoot tests to get the correct EI, first developer fixing level, and first developer time.

ChrisGalway · May 5, 2025

Donald Qualls said:
XP2 Super is easy to reverse.

First, develop in any convenient B&W developer with a very little thiosulfate or thiocyanate added (this can be adjusted to get the final density you want).
Second, expose the film to light (still on the reel generally works) -- and give it lots of light, to be sure it's completely fogged.
Then run through a standard C-41 process. Result: slightly pink B&W slides. Shoot tests to get the correct EI, first developer fixing level, and first developer time.

Thanks for this info ...

I confess when I asked the original question I was thinking more in terms of any normal B&W film, and a reversal process analogous to Kodachrome but involving only one black dye. One of the problems of reversal processing is getting a good dark black and I thought that a dye might give an improved result.

But thanks again.

Donald Qualls · May 5, 2025

If you could obtain a "black" dye coupler, that would work -- dye couplers from a color toning kit (combined with C-41 or RA-4 color developer) could do the job, but the color toners only come in single color, and mixing the toners would dilute the couplers and give a gray (it might be okay combined with retained silver, or it might not). But color toners for B&W prints aren't easy to find any more, either.

Raghu Kuvempunagar · May 5, 2025

ChrisGalway said:
One of the problems of reversal processing is getting a good dark black

Why do you think so? I can undertsand if DIY reversal didn't produce great results as it is very operator dependent but has anyone complained about either Scala process or Dr5 not producing a good dark black?

ChrisGalway said:
I was thinking more in terms of any normal B&W film, and a reversal process analogous to Kodachrome but involving only one black dye.

I would be interested in seeing your results if you take this route. IIRC @Ian Grant has posted useful info on dye couplers which might be helpful to you.

Augustus Caesar · May 5, 2025

ChrisGalway said:
Has anyone tried B&W reversal processing using a chromogenic (black) dye process?

Might it offer any advantages (reduced grain?) or disadvantages? I note that Ilford XP2 for example uses a chromogenic process ... but it's a negative, not positive, process.

You can run XP-2 through E-6.

Raghu Kuvempunagar · May 5, 2025

Raghu Kuvempunagar said:
IIRC @Ian Grant has posted useful info on dye couplers which might be helpful to you.

Here it is: https://www.photrio.com/forum/resources/toning-by-colour-development.256/

ChrisGalway · May 6, 2025

Augustus Caesar said:
You can run XP-2 through E-6.

I never thought of that! Have you (or anyone else) tried that? Any tips to suggest?

ChrisGalway · May 6, 2025

Raghu Kuvempunagar said:
Why do you think so? I can undertsand if DIY reversal didn't produce great results as it is very operator dependent but has anyone complained about either Scala process or Dr5 not producing a good dark black?

I've reversal processed Rollei Superpan 200 using the Scala kit. The results are quite nice but the blacks could be darker. (I use 120 size, and the Scala 50 film is not available in that size.)

As for Dr5, everyone says it was excellent, but the processing procedure still appears to be secret. (Is there any update on this I wonder?). Because it is said to work so well on all films, not just high silver content films, perhaps it uses a chromogenic process?

abruzzi · May 6, 2025

ChrisGalway said:
I never thought of that! Have you (or anyone else) tried that? Any tips to suggest?

Not with XP2, but I have tried with a few old rolls of Kodak T400CN, and it worked. I had to over expose (not sure if this is just negative to positive or the fact the the film was 20 years old.) The result was very green. I'd be curious if XP2 is also green, or some other color.

Raghu Kuvempunagar · May 6, 2025

ChrisGalway said:
I've reversal processed Rollei Superpan 200 using the Scala kit. The results are quite nice but the blacks could be darker. (I use 120 size, and the Scala 50 film is not available in that size.)

As for Dr5, everyone says it was excellent, but the processing procedure still appears to be secret. (Is there any update on this I wonder?). Because it is said to work so well on all films, not just high silver content films, perhaps it uses a chromogenic process?

It's unlikely that Dr5 used any such thing. You can always use Chromium intensification to add imagewise density to the slide if the blacks are not dark enough.

alecrmyers · May 16, 2025

I have been researching this idea from the point of view of diffusion transfer printing (and wondering whether there is a dye-developer that gives a black image). Things I have read suggest that nobody has ever found the holy grail of a real black dye coupler. Does anyone know different?

Raghu Kuvempunagar · May 17, 2025

alecrmyers said:
I have been researching this idea from the point of view of diffusion transfer printing (and wondering whether there is a dye-developer that gives a black image). Things I have read suggest that nobody has ever found the holy grail of a real black dye coupler. Does anyone know different?

There is a patent that @dE fENDER brought to my notice in a previous dicussion:

https://patentimages.storage.googleapis.com/5d/d0/6e/b9f0201d5c6367/EP0568777A1.pdf

B&W Reversal using a Chromogenic Process?

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