C41, bleach and fix already processed films.

Nehalem501 · Nov 20, 2014

I recently came across the threads talking about BLIX vs bleach and fix. As PE explained that separate bleach and fix is much better for film longevity, I'm thinking about the lifetime of my first C41 films I processed with the Tetenal kit.
I was wondering if the C41 films I processed a few months ago could could be bleached and fixed again.

Rudeofus · Nov 20, 2014

Absolutely yes. You can bleach and fix as often as you want, both processes run to completion.

PS: yes, there are frequent postings here claiming that BLIXes are inferior to separate bleach&fix, but once you dig deeper you often find that Tetenal's BLIX is considered quite good. I wouldn't bother unless you have strong reason to believe that your negs/slides need more complete desilvering.

pentaxuser · Nov 20, 2014

Rudeofus said:
Absolutely yes. You can bleach and fix as often as you want, both processes run to completion.

PS: yes, there are frequent postings here claiming that BLIXes are inferior to separate bleach&fix, but once you dig deeper you often find that Tetenal's BLIX is considered quite good. I wouldn't bother unless you have strong reason to believe that your negs/slides need more complete desilvering.

Quite so. It appears and maybe even PE agrees with this that the danger with Blix is not that it is inferior to Bleach and Fix per se but that it runs more risks in terms of how effective it remains even in the medium term. Indeed I think it was PE himself that said he had produced a blix as effective as bleach, fix but it had never got to market

So as an extreme example, using blix once and dumping might well be as good a separate bleach and fix but would be very expensive this way.

Others here with a reasonable pedigree in terms of skill and knowledge that I have seen respond to the debate, remain much more "agnostic" on the weaknesses of blix if properly used and not overused.

Time will no doubt tell but it may not be telling yet as not enough time has passed with the current crop of films to say what if any problems will occur with blix processed film.

pentaxuser

Nehalem501 · Nov 21, 2014

OK thank you for your answers.
I will try this with one film and will scan it afterwards to check if I see a difference with the scan I made before.

I was also wondering if the C41 bleach and fix baths could be used for ECN2 and E6 films too ? (Of course the developer baths used would still be the ones specific to each process)

Rudeofus · Nov 21, 2014

@pentaxuser: the issue with BLIX seems to be storage. The Ferric EDTA will oxidize the Thiosulfate, and as a result it will be a weaker bleach with a weaker fixer. Unfortunately it is not within our amateur means to measure retained silver in film clips, therefore we can't really test reliably whether BLIX did its job unless the fault is very obvious.

@Nehalem501: there are different C-41 bleaches, some are based on Ammonium Ferric EDTA, others are based on Ammonium Ferric PDTA. In case you aren't sure what you have: Ammonium Ferric EDTA based bleach looks like the Tetenal BLIX you used, whereas Ammonium Ferric PDTA based bleach is green and more dilute. Only those based on Ammonium Ferric EDTA are rated for E-6 film. While lots of people (including me) have reported success with E-6 film and Ammonium Ferric PDTA or even Ferricyanide based bleaches, emulsion makers won't test their E-6 stock against these stronger bleaches.

Nehalem501 · Nov 25, 2014

I was thinking about trying the Digibase C41 kit because it is possible to buy the products separately.
From the photos I've seen, the bleach seems to be Ammonium Ferric EDTA in this kit. (As the solution looks red on these photos)

Rudeofus · Nov 25, 2014

If you mean this kit, its MSDS suggests that the bleach is based on Ammonium Ferric PDTA.

Nehalem501 · Nov 26, 2014

Well, I'll see for myself when I'll buy the kit.
However the product doesn't look green for me on these photos (as you said PDTA bleach have a green colour).
https://www.flickr.com/photos/32856926@N06/5500855642/
http://www.macodirect.de/chemistry-...ollei-digibase-ebrbleacher-1000ml-p-1205.html

Rudeofus · Nov 26, 2014

The first image shows bleach that has been put through a lot of use. It is obviously Ammonium Ferric PDTA because it is fairly clear. Ammonium Ferric EDTA bleach is much more concentrated and therefore fully opaque. The second image shows an original bottle which contains a liquid with a distinct green/yellow/brown cast. That's Ammonium Ferric PDTA bleach.

As I mentioned before, most likely your E6 slides will survive this bleach, but there is no guarantee.

Nehalem501 · Nov 27, 2014

Ok.
One last question, is there a difference between B&W fixer and the fixer used in colour processes ?
For example would it possible to use this fixer in C41/ECN-2/E6 processes ?
http://www.macodirect.de/chemistry-...tenal-tetenal-superfix-plus-liter-p-1430.html

Rudeofus · Nov 27, 2014

One important property of color fixers (both C-41 and E-6) is their pH: 6.5. Most B&W rapid fixers have lower pH, IIRC about 5.5. Of course, with a pH meter, you can dial in pH 6.5 by adding the correct amount of Ammonia.

Truzi · Nov 28, 2014

I have read that color fixer can be used for B&W, and that TF-5 can be used for both, having the correct pH for color (search APUG for this).

Rudeofus · Nov 28, 2014

Truzi said:
I have read that color fixer can be used for B&W, and that TF-5 can be used for both, having the correct pH for color (search APUG for this).

TF-5 is indeed suitable for both B&W and color work, but you should be careful with color fixer for B&W. The Ammonium Thiocyanate commonly found in color fixer may weaken the emulsion, and unhardened film could potentially suffer from this. B&W films made by Kodak, Fuji and Ilford (and possibly others) are properly prehardened and should be fine.

C41, bleach and fix already processed films.

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