More on C41 fix for B&W

Photo Engineer · Apr 29, 2006

I have been working on chemistry related to the C41 RA Fixer with B&W films, and find that with incorrect dilution (using it too concentrated), I can reticulate some B&W films.

So, this is a warning.

Use of C41 RA Fixer, without proper dilution, may severely reticulate some B&W films depending on film, dilution and temperature.

This is not about the normal Flexicolor C41 fixer. This applies to the RA C41 fixer used at high concentration.

I have tested this with Ilford and EFKE films, and they reticulate. I have not tested it with Fuji B&W nor Kodak B&W. I have none of the former, and just sheet film of the latter. I have to get a few rolls of EK 35mm and test it out.

AGAIN-- This applies only to the RA fixer used at higher than normal concentrations.

PE

dancqu · Apr 29, 2006

Photo Engineer said:
This applies to the RA C41 fixer used at high concentration.
I have tested this with Ilford and EFKE films, and they reticulate.
PE

A case of high ionic strength and osmotic pressure.
Pressure builds up in the emulsion on transfer to a solution
of low ionic strength. Film and paper emulsions do not exactly
qualify as semi-permeable membranes but do posses some
of that character. The small swift H2O molecules will
diffuse quickly into the emulsion. The emulsion
expands in three dimensions.

Personally I can't think of any reason to use film fixer
other than very dilute, one-shot. Dan

Photo Engineer · Apr 29, 2006

dancqu said:
A case of high ionic strength and osmotic pressure.
Pressure builds up in the emulsion on transfer to a solution
of low ionic strength. Film and paper emulsions do not exactly
qualify as semi-permeable membranes but do posses some
of that character. The small swift H2O molecules will
diffuse quickly into the emulsion. The emulsion
expands in three dimensions.

Personally I can't think of any reason to use film fixer
other than very dilute, one-shot. Dan

Dan, if this were the case, it would happen in any concentrated fix, but it only seems to occur in the presence of some chemicals that promote swell. It is related to the specifica RA C41 chemistry and does not affect color flms in any way.

It does not appear to be related to osmotic pressure or ionic strength per se. It appears to be related to the hardness of B&W materials, and may also be related to the presence of polymers in B&W coatings.

PE

donbga · Apr 29, 2006

Photo Engineer said:
I have been working on chemistry related to the C41 RA Fixer with B&W films, and find that with incorrect dilution (using it too concentrated), I can reticulate some B&W films.

Use of C41 RA Fixer, without proper dilution, may severely reticulate some B&W films depending on film, dilution and temperature.

This is not about the normal Flexicolor C41 fixer. This applies to the RA C41 fixer used at high concentration.

I have tested this with Ilford and EFKE films, and they reticulate. I have not tested it with Fuji B&W nor Kodak B&W. I have none of the former, and just sheet film of the latter. I have to get a few rolls of EK 35mm and test it out.

AGAIN-- This applies only to the RA fixer used at higher than normal concentrations.

PE

This is great news PE. I've been looking for an easy reliable way to reticulate B&W film.

Thanks!

john_s · Apr 29, 2006

I assume that you would want to use RA fixer only if you wanted to fix very quickly? Where I live, Kodak RA is about 3.5x the price of their ordinary Flexicolor C-41 fixer. At one stage, I was considering a blend of the two for paper (suitably diluted), since fixing can be a bottleneck for me, but I decide that it might be risky, and testing for long term stability too difficult.

Of the colour fixers generally available, which would be suitable for B+W paper? From Kodak there is Flexicolor, Flexicolor BNP and Flexicolor RA and at least one E-6 fixer.

I've been using Agfa FX-Universal for years, but now I've got some ordinary Flexicolor fixer which I've not yet used. It has pH of 6 or so, whereas the Agfa was just over pH=7.

Photo Engineer · Apr 29, 2006

John;

Any of the color fixers will work at the proper dilution, and as long as you don't mix color and B&W film in the same fix. It would probably be best though just from economics to avoid the RA film fix, then you would not have to worry about reticulation.

PE

Photo Engineer · Apr 29, 2006

donbga said:
This is great news PE. I've been looking for an easy reliable way to reticulate B&W film.

Thanks!

I would suggest using it without dilution then, on a processed strip of negatives that you want to reticulate. Just dunk the negatives into the fixer for about 2' at RT. Take them out and wash them then treat in photo flo and dry.

Unlike some reticulation, this is very smooth and regular and appears to intensify during drydown. You can hardly see it while wet.

PE

srs5694 · Apr 30, 2006

What would be the appropriate RC paper fixing times when using Flexicolor fixer? (I know I can test for proper fixing and figure this out myself, but it'd be helpful to have some ballpark figures with which to start.) Also, by "proper dilution," do you mean the dilution as specified on the bottle, or something else for paper?

Photo Engineer · Apr 30, 2006

srs5694 said:
What would be the appropriate RC paper fixing times when using Flexicolor fixer? (I know I can test for proper fixing and figure this out myself, but it'd be helpful to have some ballpark figures with which to start.) Also, by "proper dilution," do you mean the dilution as specified on the bottle, or something else for paper?

RA paper fix is quite different than RA film fix. RA paper fix is more akin to the regular C41 fixer.

Paper fix is much more dilute than film fixer. I would hesitate to give you a specific. When I use a color fixer for paper, such as C41, I dilute as normal and then use the retained silver test to determine the time for each paper I use. I find that I get different fix times for EK papers than I do for Ilford papers for example. So, my suggestion is that you have to dilute and test.

PE

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