FPP’s 3-Bath Powder C-41 Kit with Separate Bleach and Fixer

1. There appears to be no source for powder Ammonium Ferric EDTA, therefore all these powdered kits rely on Sodium Ferric EDTA. I have not found an MSDS for this particular kit, but all the other powder kits use the sodium salt. Sodium Ferric EDTA will work, but it is weaker than its ammonium counter part.
2. Chromogenic film needs a bactericide in the final rinse. These bactericides in concentrated powder form are very toxic and are therefore kept out of hands of ordinary people. Thus it is quite difficult to supply these in a powder kit. That final rinse is still needed, though, and serious amateurs will have to mix something from Formalin and a wetting, thereby reducing the convenience of these kits.

woodlandSerenade said:

From what I can tell, the FPP kit is ECN-II, not C-41. That explains the higher than normal development temp and IMO poor shelf life once mixed. The developer went off in under two months in sealed, inert-gas buffered glass bottles. However, I did get good results before the developer died, and I'm sure the bleach and fixer were nowhere near exhausted.

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Rudeofus said:

I, for one, welcome a new powder kit, since it is much easier to ship powders compared to liquids, and I especially welcome a new powder kit with separate bleach and fixer. However, as a powder kit it still suffers from two weaknesses which one should be aware of:

1. There appears to be no source for powder Ammonium Ferric EDTA, therefore all these powdered kits rely on Sodium Ferric EDTA. I have not found an MSDS for this particular kit, but all the other powder kits use the sodium salt. Sodium Ferric EDTA will work, but it is weaker than its ammonium counter part.
2. Chromogenic film needs a bactericide in the final rinse. These bactericides in concentrated powder form are very toxic and are therefore kept out of hands of ordinary people. Thus it is quite difficult to supply these in a powder kit. That final rinse is still needed, though, and serious amateurs will have to mix something from Formalin and a wetting, thereby reducing the convenience of these kits.

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pentaxuser said:

Does that mean it is ordinary hypo powder that you can buy in bulk for b&w film?

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cmacd123 said:

their is at least one way (see the AGFA 304 formula) to make a dry powder Rapid fixer.

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halfaman said:

Cinestill C41 powder chemistry uses indeed sodium ferric EDTA attending to the MSDS file but for a Blix. They give the same processing time than the liquid chemistry with ammonium ferric EDTA, 8 minutes. I have some concerns about Cinestill powder efficiency after reading your comment.

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1. If you look at ion size in hydrated form, you have Li+ > Na+ > K+ > NH4+. Larger cation/hydration clusters move slowlier through gelatin, therefore from this point of view you want predominantly ammonium or maybe potassium (more on those later) ions in your solution. There are studies, which require no more than 50% ammonium ions to reach optimum speed, this is how Sodium Thiosulfate based fixers gain their speed. In other words: Cinestill's BLIX may be just as fast as a BLIX mixed from mostly ammonium salts.
   
2. There are mixed salts of alkali ion, silver, halide and thiosulfate, some of which are very poorly soluble. This means, if you have certain alkali ions present in high amounts, even relatively small quantities of silver halides will form these mixed salts and thereby end the useful life of fixer. This effect is most pronounced for potassium, but it also happens with sodium, whereas ammonium ion does not suffer from this. Obviously this does not affect performance of bleaches, but it does affect BLIX and fixer. If you have lots of sodium or potassium in your bleach (e.g. Potassium Ferricyanide, or now with this new FPP kit bleach), you must at least provide a good wash between bleach and fixer. A BLIX with lots of sodium ions will have lower capacity than a correctly formulated one made from mostly ammonium salts.

AgX said:

You might reconsider your wording for better understanding of the difference in effect of using Sodium- or Ammonium-salts at point 1.

Also at first reading one might overlook that the difference lies in speed versus capacity. If that is what you mean at point 2.

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• Ron's Superfix I recipe is all ammonium, except for 10 g/l Sodium Sulfite. These 10 g/l do not seem to degrade fixer capacity.
• A quick fixer made from Sodium Thiosulfate and 0.5-1M of some ammonium salt can be as fast as rapid fixer, but its capacity will be degraded.
  
• A bleach based on Sodium Ferric EDTA and Ammonium Bromide will be fine (i.e. normal speed and capacity), but using Sodium Ferric EDTA and Potassum Bromide will give a slower bleach, and Sodium Ferric EDTA plus Sodium Bromide would be even slower (remember the size comparison for hydrated ions).
• A BLIX made from Sodium Ferric EDTA and Ammonium Thiosulfate will be as fast as one made from Ammonium Ferric EDTA and Ammonium Thiosulfate, but the capacity of the former version will be lower.

1. C-41 and E-6 emulsions use the most advanced silver halide grain technology, which means in practice, that they are rather high in iodide. Capacity degradation due to presence of sodium or potassium ions is more pronounced with bromide and iodide.
2. C-41 and E-6 products use three times the number of emulsions to support three colors, therefore silver and halide load is three times that of B&W films.
   
3. C-41 (but not E-6) emulsions use DIR couplers. These are like color couplers, but their purpose is not to form dyes, but to release powerful restrainers like PMT (Phenyl Mercaptotetrazol). These released PMT molecules will immediately form highly insoluble silver salts, which are very hard to fix, especially if the fixer is already loaded near its capacity. These DIR couplers are our friends: they allow a hard push, giving excellent shadow speed, while keeping contrast in check (since development is restrained mostly where development already released these restrainers). They also create the same edge effects which we know from dilute developers. So we want these DIR couplers in there, even if they require us to use slightly more expensive fixers.

Rudeofus said:

Yes, (1) addresses speed of action, whereas (2) is meant to address capacity. You can reach good speed of action with up to 50% sodium and just 50% ammonium ion, but capacity will always be poor with more than let's say 10% sodium or potassium ion in solution.

Allow me to provide some examples:

• Ron's Superfix I recipe is all ammonium, except for 10 g/l Sodium Sulfite. These 10 g/l do not seem to degrade fixer capacity.
• A quick fixer made from Sodium Thiosulfate and 0.5-1M of some ammonium salt can be as fast as rapid fixer, but its capacity will be degraded.
  
• A bleach based on Sodium Ferric EDTA and Ammonium Bromide will be fine (i.e. normal speed and capacity), but using Sodium Ferric EDTA and Potassum Bromide will give a slower bleach, and Sodium Ferric EDTA plus Sodium Bromide would be even slower (remember the size comparison for hydrated ions).
• A BLIX made from Sodium Ferric EDTA and Ammonium Thiosulfate will be as fast as one made from Ammonium Ferric EDTA and Ammonium Thiosulfate, but the capacity of the former version will be lower.

Color film wants a rapid fixer for three reasons:

1. C-41 and E-6 emulsions use the most advanced silver halide grain technology, which means in practice, that they are rather high in iodide. Capacity degradation due to presence of sodium or potassium ions is more pronounced with bromide and iodide.
2. C-41 and E-6 products use three times the number of emulsions to support three colors, therefore silver and halide load is three times that of B&W films.
   
3. C-41 (but not E-6) emulsions use DIR couplers. These are like color couplers, but their purpose is not to form dyes, but to release powerful restrainers like PMT (Phenyl Mercaptotetrazol). These released PMT molecules will immediately form highly insoluble silver salts, which are very hard to fix, especially if the fixer is already loaded near its capacity. These DIR couplers are our friends: they allow a hard push, giving excellent shadow speed, while keeping contrast in check (since development is restrained mostly where development already released these restrainers). They also create the same edge effects which we know from dilute developers. So we want these DIR couplers in there, even if they require us to use slightly more expensive fixers.

If you have an extremely cheap source of Sodium Thiosulfate, you can use it to make a neutral fixer for color film, but be prepared to use it single shot.

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woodlandSerenade said:

From what I can tell, the FPP kit is ECN-II, not C-41. That explains the higher than normal development temp and IMO poor shelf life once mixed. The developer went off in under two months in sealed, inert-gas buffered glass bottles. However, I did get good results before the developer died, and I'm sure the bleach and fixer were nowhere near exhausted.

Click to expand...