Converting C-41/E-6 BLIX into Separate Bleach and Fixer

[Rudeofus]

Rudeofus submitted a new resource:

(there was a url link here which no longer exists) - Converting C-41/E-6 BLIX into Separate Bleach and Fixer

1 Introduction

Many C-41 and E-6 kits come with BLIXes to remove silver. These BLIXes sometimes don't work all that well, and some of the BLIX concentrates have limited shelf life. The main purpose of this document is to provide a brief introduction into the composition and inner working of bleaches and BLIXes. We then use this knowledge to convert BLIX concentrates and powders as provided by kit makers into separate bleaches and fixers, using only compounds that can be...

(there was a url link here which no longer exists)

 

[Rudeofus]

A quick update regarding identification whether a kit is bleach&fix vs. BLIX: There is a kit sold in the US under the "Rollei" brand which is a liquid BLIX kit, unlike the Rollei Digibase kits sold in Europe. To add to the confusion, there was a kit sold in the US under the Rollei Compard brand, which provided separate bleach and fixer.

 

[chazum0]

A quick update regarding identification whether a kit is bleach&fix vs. BLIX: There is a kit sold in the US under the "Rollei" brand which is a liquid BLIX kit, unlike the Rollei Digibase kits sold in Europe. To add to the confusion, there was a kit sold in the US under the Rollei Compard brand, which provided separate bleach and fixer.

I noticed this last night while I was searching around for separate bleach and fix C-41 kits. It appears that the only liquid 1-5L C-41 kits with separate bleach and fix chemicals are available exclusively in Europe.

 

[chazum0]

What are the visual signs of exhausted/ inadequate bleaching?

 

[Rudeofus]

What are the visual signs of exhausted/ inadequate bleaching?

Incomplete bleaching of slides shows up as brown background color, and this color in negatives is barely visible to our eyes, but will show up when you scan or print the negatives. Assume that bleaching is like fixation: it's very difficult to determine whether it is complete, so rather stick to established recipes and times unless you are willing to deal with the consequences of incomplete bleaching.

 

[Xmas]

What are the visual signs of exhausted/ inadequate bleaching?

I believe that some low budget movies 'held back' the bleach on some scenes to achieve a synthetic SiFi effect before post processing digitally was effective, but can't find a link, so you won't like what you get...

 

[bvy]

I believe that some low budget movies 'held back' the bleach on some scenes to achieve a synthetic SiFi effect before post processing digitally was effective, but can't find a link, so you won't like what you get...

http://en.wikipedia.org/wiki/Bleach_bypass

One such movie:
http://en.wikipedia.org/wiki/Her_Brother

 

[Xmas]

http://en.wikipedia.org/wiki/Bleach_bypass

One such movie:
http://en.wikipedia.org/wiki/Her_Brother

Thanks

 

[chazum0]

Incomplete bleaching of slides shows up as brown background color, and this color in negatives is barely visible to our eyes, but will show up when you scan or print the negatives. Assume that bleaching is like fixation: it's very difficult to determine whether it is complete, so rather stick to established recipes and times unless you are willing to deal with the consequences of incomplete bleaching.

If memory serves me correct, it seems as though PE once mentioned that it's possible to test the strength/ useful capacity by agitating a fully fixed black and white print in a tray of bleach and watching to see if the blacks fully turn to white. I'll have to do a search on the forum to find it. I'm also not sure if he was refering to RA-4 bleach or C-41 bleach.

 

[Photo Engineer]

That is the test for a good RA4 BLIX.

PE

 

[chazum0]

That is the test for a good RA4 BLIX.

PE

Thanks PE! I'd be overwhelmingly lost without your knowledge!

 

[Paul Verizzo]

This is amazing information, and perfect timing for me in my quests.

My only question is, is there anything particularly wrong with using potassium bromide instead of ammonium bromide with iron EDTA and PDTA? (Unicolor.) I just hate buying yet another chemical and paying more for shipping than the chemical!

Since potassium bromide is used with ferricyanide to make bleach, I'm jus' wunnering, ya know?

 

[Rudeofus]

My only question is, is there anything particularly wrong with using potassium bromide instead of ammonium bromide with iron EDTA and PDTA? (Unicolor.) I just hate buying yet another chemical and paying more for shipping than the chemical!

Since potassium bromide is used with ferricyanide to make bleach, I'm jus' wunnering, ya know?

When it comes to counter cation, the same rules apply that apply to fixation: Ammonium is better than Sodium, and Sodium is better than Potassium. If you compare the speed of Sodium Thiosulfate vs. Ammonium Thiosulfate (the latter has 2 1/2 times faster clearing time), you can imagine what will go on in a bleach that contains only Sodium and/or Potassium.

Now you could say "well, if it's that much cheaper/easier, I don't mind if bleaching takes 12-15 minutes". The problem with this is that neither of us knows, whether 12-15 minutes are enough, and neither of us has access to equipment (read: X-ray fluorescence apparatus) that could tell us reliably if bleaching was complete. With Ammonium Ferric EDTA plus Ammonium Bromide there are many commercial products which all work within 6 minutes at 38°C/100°F, so we can assume if we mix something similar, that we will get similar results. While retained silver will initially show of as neutral density (which we may not care about), it will eventually convert into Silver Sulfide, and that conversion will not happen uniformly.

So that's what we are up against, and that's why I suggested we have as much Ammonium ion vs. Sodium or Potassium ion as possible in our bleach and fixer. If you look at patent US5275923, fixer can have 60:40 ratio of Sodium to Ammonium and still act as rapid fixer. Hence, the combination of Ammonium Ferric EDTA and Potassium Bromide can be expected to work, and indeed, that's what (there was a url link here which no longer exists) use. Likewise I would expect a bleach based on Sodium Ferric EDTA and Ammonium Bromide to work well.

If you plan on doing lots of C-41/E-6 work, you can order a larger amount of Ammonium Bromide to make shipping worthwhile, it's a stable compound which should last you a long time.

 

[Paul Verizzo]

@ rudeofus: thanks for your reply. I only had HS chemistry and have been self-taught on photochemistry since then. Not so much at the molecular level, more macro-ish.

A few years ago I did a lot of simple research on fixers, might be of interest: (there was a url link here which no longer exists)

OK, so when using Blix, the ammonium is supplied by the fixer, I take it, for the EDTA. And w/o wash, bromide coming from the developer?

I'm on a very modest retirement budget, so for me, whatever I don't have to spend is good. I see Artcraft as 50g of ammonium bromide for $13, plus shipping. One time Mike there sent me ammonium sulfate by accident, he said to just keep it. Is this what I've been saving it for? Could it work? The Unicolor Bleach has sodium sulfite in it, too, FYI, but you probably know that. Ammonium sulfate and potassium bromide?

I know, I just shotgunning ideas w/o any solid knowledge here. It's been a half century, I no longer remember which things would do what.

Thanks for your help.

 

[Photo Engineer]

Sulfate ion slows both bleaching and fixing.

Mees shows that too much Potassium can stop fixing.

Bromide is not coming from the developer in any substantial quantity so I am not sure what you mean here. I can assure you that the solution is balanced from an ionic standpoint.

PE

 

[Paul Verizzo]

@ rudeofus: OK, now I'm really going to go out on the weird limb. What about non-sudsing cleaning ammonia (dissolved hydroxide, right?) and potassium bromide?

Ouch, ouch, stop hitting me!

 

[Photo Engineer]

At this point, Sodium Bromide or Sodium Chloride would be better.

Potassium slows down fixation. Actually, due to the way things are arranged atomically, Potassium salts are slower to react due to the larger size of the Potassium ion in many cases.

Check with Rudi on this though, as he has done these experiments.

PE

 

[Rudeofus]

A bleach uses a "push" and a "pull" component: the oxidizer "pushes" the silver towards silver ion, and a good counter anion "pulls" the silver ion out of the equation. Since Ferric EDTA is a very weak oxidizer, we need a counter anion with decent "pull". From this perspective alone, Sulfide or Iodide would be the ideal counter anions, but don't even think about fixing Silver Sulfide, and even Silver Iodide would require a very strong fixer. Bromide strikes the perfect balance between "strong pull" and "reasonably easy to fix". While Silver Chloride is very easy to fix, Chloride would not create enough "pull", bleaching would never be complete.

How does one know about the "pull" of a counter anion? It's mostly determined by how tightly the counter anion binds silver ions, i.e. takes them out of the reaction. Compounds which form very insoluble silver salts, or which form very tight silver complexes, have stronger "pull". "Pull" also becomes stronger the higher the concentration of that counter anion.

Another thing we need to consider is ionic strength: the more ions you stuff into a solution, the less effective they will be. As a result, I predict lower bleaching speed from Potassium Bromide plus Ammonium Sulfate than from Ammonium Bromide. Your fixer experiments show the same trend: Ammonium Thiosulfate is faster than Sodium Thiosulfate plus Ammonium Chloride/Sulfate, and excessive Ammonium Chloride slows down fixation.

Now since I related several bleach properties to fixer properties, and since cost appears to be of concern: whenever we want to know how long fixer needs to properly fix film, we measure clearing time and say "double it!" for proper fixation. We could try the same thing with bleach: bleach a test clip long enough that no retained silver is visible, then say "double it!". At least with E6 this should work, as the clear base will reveal brown silver residues. Note that is method is unproven, and that we have no method accessible to us amateurs which could verify complete silver removal, so you are out on your own.

One final thing: if you add Ammonia to your bleach, you raise its pH, and above pH 7 it will stop working.

 

[Paul Verizzo]

I knew going into this that ammonia solution (hydroxide) is high pH, but I won't try to pretend I can take my questions and derive an answer from your gracious, thought out post!

Ammonium sulfate?

Ammonium hydroxide in cleaning product?

 

[Rudeofus]

Ammonium sulfate?

Ammonium hydroxide in cleaning product?

Ammonium Hydroxide is the same as Ammonia, so you're back to square one. I have made one experiment, where I bleached slides with a mixture of 200 ml/l Ammonium Ferric EDTA 50%, 100 g/l Ammonium Chloride and 100 g/l Ammonium Bromide, and after 10 minutes of bleaching I still had a visible brown silver residue in my slides. Ammonium Ferric EDTA with only the 100 g/l Ammonium Bromide left no such residue. I would expect even worse nastiness from Sodium Ferric EDTA, Potassium Bromide and Ammonium Sulfate, but have no experimental data to back up my claim.

The best method for avoiding an Ammonium Bromide purchase is getting a liquid kit. Now you'll ask "but why should I throw away my powder kit?", to which I say: "you don't have to throw it away". A bleach mixed from liquid BLIX part 1/A and 100 g/l Potassium Bromide will last much longer and has much, much higher capacity than a BLIX made from the same concentrate, therefore you can use the bleach you make from the liquid kit to bleach slides/negs developed by both your powder and your liquid kit.

 

[Paul Verizzo]

Continuing thanks, Rudeofus. One hundred grams of ammonium bromide from Artcraft is $26 plus shipping. digitaltruth doesn't list it, and I'm not familiar with any other chemical vendors.

The liquid kits are insanely priced, around $50 for a liter, $75 for five liters. Crazily non-linear. Yes, the five liter kits are reasonably priced, but for me, I can't justify that hit for something of just interest.

 

[Photo Engineer]

Can you get some Potassium Ferricyanide? If so, you can make a fine bleach - then fix process up that at least should serve you in color processes. Then you develop, clear in acid sulfite, wash bleach, wash and then fix and stab. This is C41 and is much the same for E6. This will probably affect image stability, but it will serve.

PE

 

[Rudeofus]

Paul, I agree that Ammonium Bromide is outrageously expensive in the US, so here is what I recommend:

1. Dilute the BLIX part A of your package in 0.8 liters of water
2. Take 400 ml of this solution and put it into a beaker which holds at least 500ml
3. add 50 g Ammonium Bromide from Artcraft to this mix
4. Then proceed with pH adjustment as described in this article and fill up to make 500ml

This sets you back US$ 13.50 plus shipping, and gives you a bleach which will bleach all the films you process with this kit, and then some. Once you start enjoying colour processing, you should look at liquid 5l kits and Potassium Bromide. Such a 5l kit will last for well over a year if you protect the opened concentrate bottles with inert gas.

 

[Paul Verizzo]

I've done some research on ferricyanide bleaches on C-41 and I think that's the way to go for me. I have a fair amount of the ferricyanide and bromide. I've pulled up an E6 suggestion and Kodak SR-29 bleach and replenisher. I like the latter concept. Simple.

PE, what is this acid sulfide bath you are referring to? Is this something like thiosulfate in B&W reversal to clear the highlights?

 

[Photo Engineer]

I said "ACID SULFITE" which is a different animal.

PE