Chromogenic B&W film ????

George Papantoniou · Aug 16, 2005

I just tried to develop a test strip of Dia-Direkt, the old Agfa B&W transparancy film. (remember, I had asked a while ago a question about it, noone answered that he/she knew how to develop it...).

It seems that there is some kind of problem. The film won't clear in the fixer (Tetenal) and I am beginning to suspect that it might have been a chromogenic film.

Does anyone know whether there are problems clearing a chromogenic film in B&W fixer (hypo) ? I know I could try to do it with a piece of colour film to see if it works, but to tell you the truth, I don't usually shoot colour (except for professional reasons) and I don't really want to waste an expensive roll of E100G 120 for the test... so some help from one of you chemistry whiz kids would be very welcome...

psvensson · Aug 16, 2005

I think chromogenic films would clear in regular fixer, it would just leave extra silver in the exposed areas, leading to higher contrast. There's probably something else wrong. Are you using reversal chemistry or just regular processing for negatives?

Helen B · Aug 16, 2005

Dia-Direct wasn't chromogenic as far as I remember, and as Peter says, chromogenic film would clear. Didn't D-D have a silver antihalation layer that would be removed during the bleach step but would not be removed during normal development to a neg.

Best,
Helen

srs5694 · Aug 16, 2005

I'll add that I've heard of people developing chromogenic B&W films as conventional B&W films, using B&W developers and fixers. I've not tried this myself, but it reportedly works, in the sense that the developer develops an image and the fixer clears the film as it should. By all accounts it doesn't work well, in the sense of producing optimum results, but AFAIK chromogenic films will clear in B&W fixers.

George Papantoniou · Aug 17, 2005

Helen B said:
Dia-Direct wasn't chromogenic as far as I remember, and as Peter says, chromogenic film would clear. Didn't D-D have a silver antihalation layer that would be removed during the bleach step but would not be removed during normal development to a neg.

Best,
Helen

Helen, this is quite possible... To answer peter's question too, the process I used was not reversal. I only wanted some negs to print... I guess now I have to try reversal processing... or just bleach the film after first developing it and then, instead of clearing, fogging etc, just redeveloping it and fixing. It might work, no ?

Helen B · Aug 17, 2005

"I guess now I have to try reversal processing... or just bleach the film after first developing it and then, instead of clearing, fogging etc, just redeveloping it and fixing. It might work, no ?"

Whatever you do needs to discriminate between the image silver and the AH silver. There are two features that may enable discrimination:

Before development the latent image silver may be protected from some bleach, suggesting pre-development bleaching. This doesn't strike me as a sensible way to go without a lot of experimentation.

During development: use a strongly staining developer, then select a bleach (like ferricyanide) that will not remove the stain image.

Best,
Helen

George Papantoniou · Aug 18, 2005

Helen B said:
"I guess now I have to try reversal processing... or just bleach the film after first developing it and then, instead of clearing, fogging etc, just redeveloping it and fixing. It might work, no ?"

Whatever you do needs to discriminate between the image silver and the AH silver. There are two features that may enable discrimination:

Before development the latent image silver may be protected from some bleach, suggesting pre-development bleaching. This doesn't strike me as a sensible way to go without a lot of experimentation.

During development: use a strongly staining developer, then select a bleach (like ferricyanide) that will not remove the stain image.

Best,
Helen

This is beginning to get complicated... What about developing, fixing, then bleaching (ferricyanide bleach) and lastly redeveloping ???

raucousimages · Aug 18, 2005

Developing chromogenic film in B&W chemistry will not work. I have had several students try it after purchasing chromogenic film at the grocery store instead of going to a photo store. It gives a VERY VERY thick uncleared neg. you just can't print through it.

Helen B · Aug 18, 2005

"This is beginning to get complicated... What about developing, fixing, then bleaching (ferricyanide bleach) and lastly redeveloping ???"

Traditional ferricyanide bleach produces insoluble silver ferrocyanide, which is then usually removed by hypo. Ferricyanide with potassium bromide instead of hypo will act as a rehalogenating bleach, as will an acidic solution of copper sulphate in the presence of halide ions.

But how will the redeveloper distinguish between the silver halide formed from the AH silver and that from the image silver?

How will developing in a staining developer then fixing then bleaching (develop-fix-bleach) be any more complicated than develop-fix-bleach-redevelop?

Raucousimages' comment about chromogenic B&W film suggests that whichever film is being referred to might also use silver for the antihalation layer. Which film was it, by the way? I haven't tried developing chromogenic B&W film in normal B&W chemistry since the days of XP-1. That worked OK.

Best,
Helen

terot · Aug 19, 2005

When I shot Agfa DD 12 (and 32) many years ago (when it was last available),
I did, indeed, reverse it to a nice B&W slide using the following chemistry:
Tetenal Black & White Slide Kit (cat. nr. 0204) - and of course no longer available.
It was sufficient for 4 * 135-36 films and fogging was done by (white) light.
DD was an (ordinary) silver halide film and the 1st development time was 3 mins,
temperature 20 C. I rated it DD 12 at EI 20 for this purpose, with some bracketing around. Results were good, with a very slight brownish cast, i.e. seemingly the film
hadn't a clear base and/or AHU which would completely clear out during reversal.

As many of us know, the reversal goes like this (after exposure):
- 1st dev.
- bleach
- clear (neutralize the bleach)
- fogging by light (or chemically !)
- 2nd dev.
- fix
- HCA
- wet

If you want to shoot B&W slides you should prefer films with a clear base and an
AHU which clears out completely (or no AHU at all !). Then you will get all the
wonderful luminosity which only a B&W slide can have !
During the years I have experimented a lot with various B&W films and their
reversal processes. Now I use a "standardized" method and "clear" films only (like
Maco ORT or PO or Cube or Agfa Scala)...

rgds
TT

George Papantoniou · Aug 19, 2005

Helen B said:
But how will the redeveloper distinguish between the silver halide formed from the AH silver and that from the image silver?

How will developing in a staining developer then fixing then bleaching (develop-fix-bleach) be any more complicated than develop-fix-bleach-redevelop?

Helen, the only silver left after fixing will be the image silver... thus the second developer could only redevelop the image silver... I can use the (rehalogenating) bleach from the first bath of Kodak Sepia toner... (easy to find).

The dual developing method I propose is far superior to the one with the staining developer because it's really hard to find a staining developer here in Greece... unless I use instant coffee (+alkali) to develop my film, something that has worked in the past but is not considered a reliable method...

George Papantoniou · Aug 19, 2005

terot said:
DD was an (ordinary) silver halide film and the 1st development time was 3 mins,
temperature 20 C. I rated it DD 12 at EI 20 for this purpose, with some bracketing around. Results were good, with a very slight brownish cast, i.e. seemingly the film
hadn't a clear base and/or AHU which would completely clear out during reversal.

TT, thank you for the info. I can imagine that using the usual (as you described) B&W reversal process (that I have used with Tech pan, FP4 and Tmax with varying degrees of success) the results will be OK. I just wanted to have negs instead of slides. There was a couple of DD12 rolls in my fridge for the last decade that I wanted to get rid off... I took them with me and the Leica for a trip, and that is how I ended up asking around for help...
I know that DD12 didn't have a very clear base, I had used it too, but always sent it to AGFA for processing. If I wanted B&W slides now, I would surely use Scala. It's got great contrast and gives brilliant-looking images.

Helen B · Aug 19, 2005

"Helen, the only silver left after fixing will be the image silver... '

If the AH layer is silver, at what stage would it be removed in a standard develop-fix negative process? I understood that you were proposing develop-fix-bleach-redevelop, in which case a silver AH layer will survive through the fix.

Best,
Helen

George Papantoniou · Aug 19, 2005

Helen B said:
"Helen, the only silver left after fixing will be the image silver... '

If the AH layer is silver, at what stage would it be removed in a standard develop-fix negative process? I understood that you were proposing develop-fix-bleach-redevelop, in which case a silver AH layer will survive through the fix.

Best,
Helen

I am sorry, Helen. I just didn't realize that you meant that the AH silver would be metallic silver. Not very good in chemistry (hated it at school). So, this only leaves the staining developer possibility... too bad for me :-(

Chromogenic B&W film ????

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