E-6 Blix

[thuggins]

I just mixed the fifth (final) batch of Tetenal. The first dev and color dev had been decanted into smaller bottles but the blix and stabilizer were in the original 500ml bottles. Part 2 of the blix had formed a yellowish film where it filled the bottom of the bottle, I assume it had oxidized. I saw no indication of this on the previous batch mixed about five weeks ago. I've developed a roll of Velvia 50 and it looks fine.

What does part 2 do, and what is the worse case if some portion of it has oxidized?

 

[Rudeofus]

Tetenal BX2 is the Thiosulfate component of your BLIX, i.e. the component which dissolves the Silver ions created by the bleach part. If Thiosulfate disintegrates, it forms small Sulfur particles which you saw as yellow precipitate. Decanting/filtering won't help against minuscule particles, at least not with filters which amateurs are going to afford, and these tiny Sulfur particles can end up in your emulsion. Tetenal uses a poor formula for their BLIX concentrates, therefore BX2 is typically one of the first concentrates to go bad

There is no ready made replacement for Tetenal's BX2, although one could be easily made from Ammonium Thiosulfate and Acetic Acid if you are willing to invest in a pH meter. If you have no ambitions towards home brewing, throw out the remaining concentrates and start with a fresh kit.

PS&warning: I was in strict "I will never homebrew" mode until I ran into precisely your problem with Tetenal's BX2

 

[darkroommike]

Back in the early days of E6 the Imagemaker used a hybrid chemistry to process E6, the machine had no way to recover and reuse BLIX and E6 bilix was expensive. We used E6 chemicals for the first half of the process then the separate E4 bleach and Fix cycle then E6 stabilizer after washes. If you go the DIY route the separate bleach and fix are more manageable.

 

[Photo Engineer]

The C41 fix or TF5 fix will work as a replacement if you use it for about 2x the suggested blix time.

It is NOT advisable to use a blix with any color film. It is OK with paper.

PE

 

[Rudeofus]

TF-5 is near neutral, whereas Tetenal's BX2 is acidic (MSDS lists pH of 5.4 - that's why its concentrate shelf life is so poor. That's why I suggested Thiosulfate and Acetic Acid - and a pH meter, since BLIX is the final concentrated process bath and needs to be at pH 6.5.

Another option would be to convert BX1 into a rehal bleach and then use TF-5 fixer, see my article.

 

[Photo Engineer]

Well, I don't suggest the use of any blix with film as I have said over and over.

PE

 

[trendland]

Well, I don't suggest the use of any blix with film as I have said over and over.

PE

Blix from my understanding is just a concept from tetenal and others to state : This is your best and easiest way.
The same method comes against all powder developers : "This is much more easy to you - use liquit concentrates"
But what is so complicate to people when they use powder developers and mix. their shell ?
What is so complicate to use bleach and fix seperately.
In both issues limited shell live is more the trouble case.

with regards

 

[thuggins]

Thanks for all the responses; it was interesting to see I'm not the only one who has run across this.

As I had mentioned, the first roll of Velvia came out fine, so it appears the fixing is still active. If my limited understanding of the development process is correct, between the first and color developers pretty much all of the silver halide in the film is reduced to metallic silver. The bleach then oxidizes this back to silver bromide, which is dissolved out by the fix. So if the fix is not working at all, the film should darken as soon as it is exposed to light, just like undeveloped film. If the fix is partially working I could see that this might take some time. Days perhaps? A couple of weeks at the most? At any rate I will continue to use this mix on a few more rolls, just to see how it behaves. The film I'm shooting now is just camera testing stuff so it is no big deal if a roll doesn't come out.

I already have the new Tetenal kit ready to mix up for the vacation pictures. And there are a whole bunch of 100ml bottles on the way. This time I'll be able to repackage all the chemicals once they've been opened.

 

[Photo Engineer]

And, if the oxidation step is not working correctly, colloidal sliver can remain which can darken the image and can gradually yellow degrading your slides!

There are hidden dangers.

Also, make sure there is formalin in the process as there is in the E6 process.

PE

 

[thuggins]

Hi PE, thank you for your comments. They are always insightful and helpful.

But this situation has got me thinking about the chemical reactions going on, especially in the BLIX. Your objection to BLIX is well documented on these pages. But it seems to me that if you are going to combine any two steps, mixing the bleach and the fix seems like pretty sound combination.

The bleaching and fixing are both complimentary and interactive. That is to say, there is no need for the bleaching to be complete before the fixing starts. As I mentioned above, after the color developer is complete there should be little to none of the original silver halide in the film. So when you first put the film into the BLIX, there is nothing for the fix part to operate on.

Then, as the bleach oxidizes one silver atom into a silver bromide molecule, it becomes soluble and the fix dissolves it out. It essentially becomes a one to one relationship - one oxidized silver atom becomes one dissolved silver bromide molecule. This actually seems like it would be more effective than a separate bleach and fix.

 

[Photo Engineer]

Tim, let us assume that Bleach III from Kodak is an example of a good bleach. It is used as-is and is needed at that strength to oxidize all of the silver metal. Just fine, as is. Now, to make a blix out of it you have to add some level of hypo. This dilutes the oxidant! It is now less effective. In addition, hypo is a reductant. With the strong oxidant used for films, this combination is not ideal for a long shelf life. Once mixed, it goes bad fast.

With paper, this is much simpler. The blix is much more dilute and lower in oxidation potential and so such a blix is possible.

Film blxes are possible, but would be very expensive.

PE

 

[thuggins]

Hi PE, thank you for that information. You confirmed the two thoughts that I had, which was dilution of the chemicals and the potential for reaction between the two.

If I may pose one more question, in several places you have stressed the importance of formalin with E-6. I assume this is for a stabilizer. From what I have read Tetenal uses miconazol in their stabilized. Miconazol is an antifungal, but I can believe that formalin would do a better job.

As the Tetenal stabilizer also contains a surfactant, it can't just be replaced with formalin. If one were to add a formalin step to the Tetenal process, should this be done after the blix and before the stabilizer? I am assuming that you want the surfactant to be in the last bath before drying.

Alternately, could one skip the Tetenal stabilizer entirely and mix a wetting agent with the formalin? Or even have a separate wet bath after the formalin? I have a lifetime supply of Ilfotol and am trying to come up with ways to use it.

 

[Rudeofus]

I just reviewed the MSDS for Tetenal's Colortec E6 kits and their STAB lists Ethanl and Formalin. I suppose it contains a surfactant as well, and that its concentration is too low to warrant listing in MSDS. If you mix your own E6 STAB, you may use PE's formula stated here, but you'd get nothing much different than from Tetenal's STAB. PE's formula is a great first aid formula for newcomers who mix their first batch of STAB with tap water instead of deionized water.

@Blix vs. bleach&fix: Bleach III is a very powerful but quite dilute bleach, and not rated for E6, and with an ingredient which make it incompatible with Thiosulfate. As far as real E6 bleaches, fixes and BLIXes are concerned, their individual component concentrations are actually fine, it is the interaction between the components which makes it much weaker than the already weak E6 bleach:

1. Any photographically inactive or weakly active component added to fixer makes it weaker: try adding Sodium Sulfite, or Sodium Bicarbonate, or Ammonium Chloride, or Sodium Chloride to Rapid fixer in 20 g/l increments and observe its clip clearing times as sulfite content goes up. At 100 g/l either of them will at least double clip clearing times, guess what 100 g/l Ammonium Ferric EDTA will do to fixer?
2. PE already described the adverse interactions between oxidizer bleach and reducer fixer.
3. Don't overestimate bleaching power of Ammonium Ferric EDTA, this is a really really weak oxidizer, which barely bleaches silver and even then needs an accelerator to get reasonable bleaching times. There is a reason why most amateur published E6 home brew formula collection end with "you should bleach E6 with Ammonium Ferric EDTA, but here is a Hexacyanoferrate formula which always worked great yadda yadda".

 

[Photo Engineer]

Bleach III was only used as an example, but it is quite strong in spite of not being recommended for E6 films. Basically, E6 films form silver from virtually all of the silver halide coated, but negative films only form sliver from about 1/2 of the silver coated. That being said, one must remember that C41 films form powerful bleach inhibitors during development in order that the color correction chemistry be active. They are so powerful, that bleach accelerators are also coated in C41 films. None of this is present in E6 films. Other methods are used, that are not so draconian in terms of silver retention. So, in the end, both bleaches must be powerful, but in different ways.

In spite of the above paragraph, my comparison as an example still stands.

And, E6 films appear to still need formalin to preserve dyes and emulsion. More recent films use an antifungal agent for the same purpose. In older films, the couplers needed formalin to protect them from yellowing and dye fade.

PE

 

[thuggins]

I ended up developing 5 rolls in that batch before tossing it and mixing a new batch from a new kit for my vacation pics. The batch was about three weeks old and I was cross processing XP2 to make b&w slides.

I let the blix go several minutes longer than rated and the film came out with noticeable brown spots. I assumed it was the fix. It has now set for a little over two weeks and the brown spots have cleared. The images look fine now. So it must have bleached and fixed to completion.