Sourcing Ferric Ammonium EDTA in the US

[koraks]

Are Andrew's ingredients and amounts all that are needed for perfectly satisfactory C41 negatives

Yes. I've made similar developers. The differences in terms of image quality with official C41 formulas are very small.

2. Does what Andrew refer to as CD-4 come with different names in Europe and the U.K.?

No, it's referred to the same globally; as CD-4 or CD4. There are two CAS numbers that reflect a small difference, but the functional part of both molecules is the same. Shipping and duties can indeed make the material more expensive. I know of no domestic source in the UK. There are several sources in other parts of the world. They ultimately trace to China.

3. Would Andrew's amounts that he used for one film actually be OK for several films if used again within say a few hours ?

Yes; how many exactly will be a guess, but the capacity can be assumed to be the same as for commercial developers. This is usually considered to be in the 6-12 rolls per liter range.

 

[River Mantis]

Would like to make my own RA-4 and C-41 chems (mostly RA-4), but I cannot find a single source for the Ferric Ammonium EDTA anywhere. I’ve searched Artscraft, Photoforumarly, and major chemical suppliers like Flinn, CarolinaBio, and Fishers.

Without making my own, is my only option to use the alternative Ferric EDTA + Tetrasodium EDTA bleach that PE lists, or seeing if a ferricyanide bromide bleach from ECN-2 works?

It indeed works perfectly for both ECN-2 and C-41 (there is a commercial product which uses it) and allegedly for E-6 (because why shouldn't it)

 

[Rudeofus]

Following the developer, I have used a 2% acetic acid stop bath with 10 g/l sodium sulfite added to it for a couple of minutes, followed by a wash for a couple of minutes, followed by the ferricyanide bleach with no detectible staining. PE (Photo Engineer) has recommended this acid/sulfite bath many times.

There are two aspects to Ferricyanide, and both are there because Ferricyanide is a stronger oxidizer than Ferric EDTA:

1. potential staining, if Ferricyanide reacts with carryover CD-4. This is well addressed by your clearing bath.
2. loss of archival stability. Film dyes are attacked by aerial Oxygen, therefore they are typically protected by reducing agents in the emulsion. These stabilizers are potentially destroyed by out of spec bleaches. You negatives/slides will look perfect for a few years, and then fading may set in long before a properly processed negative/slide would fade.

I have no idea, why Ammonium Ferric EDTA is so hard to obtain right now, not even Sigma Aldrich seems to offer it any longer. Artcraft sells all kinds of crazy chems but not this one. Very strange indeed. The good thing is, that the procedure for making it is not that involved, it's certainly easier than mixing all 7 E-6 bathes.

 

[pentaxuser]

Yes. I've made similar developers. The differences in terms of image quality with official C41 formulas are very small.


No, it's referred to the same globally; as CD-4 or CD4. There are two CAS numbers that reflect a small difference, but the functional part of both molecules is the same. Shipping and duties can indeed make the material more expensive. I know of no domestic source in the UK. There are several sources in other parts of the world. They ultimately trace to China.


Yes; how many exactly will be a guess, but the capacity can be assumed to be the same as for commercial developers. This is usually considered to be in the 6-12 rolls per liter range.

Thanks for the reply, koraks. The Dutch seller I found will sell quite a large packet of CD4 for the same delivery charge and that way or even possibly buying others chems from him would reduce the cost proportionately and it certainly is the "for sure" way to be rid of any uncertainty about shelf life in terms of the liquid kits if your use of colour is very limited

pentaxuser

 

[RPC]

2. loss of archival stability. Film dyes are attacked by aerial Oxygen, therefore they are typically protected by reducing agents in the emulsion. These stabilizers are potentially destroyed by out of spec bleaches. You negatives/slides will look perfect for a few years, and then fading may set in long before a properly processed negative/slide would fade.

This has been addressed many times but I have yet to hear of any reports of any problems from long-time users of ferricyanide bleach for C-41. Personally, I have negatives more than 15 years old with no signs of change, and others even longer. Although not conclusive, it is encouraging, considering the aforementioned availability problems, and the wide use of scanning these days.

The rest of the process done properly is equally of concern.

 

[Rudeofus]

This has been addressed many times but I have yet to hear of any reports of any problems from long-time users of ferricyanide bleach for C-41. Personally, I have negatives more than 15 years old with no signs of change, and others even longer. Although not conclusive, it is encouraging, considering the aforementioned availability problems, and the wide use of scanning these days.

Kodak and Ilford spent decades trying to make Ferric EDTA bleaches work with their color processes. In its basic form "Ammonium Ferric EDTA plus Ammonium Bromide at pH 5" it doesn't work well, so they researched bleach accelerators and other means to produce viable bleaches. Patent over patent was written and shoved though the USPTO.

There must have been quite some incentive to create really mild yet effective bleaches.

 

[koraks]

it certainly is the "for sure" way to be rid of any uncertainty about shelf life in terms of the liquid kits if your use of colour is very limited

Yeah, that's what piqued my interest in DIY color developer mixing as well. Turns out that the commercially made developer stores very well, too. But it's a nice option to have at hand.

There must have been quite some incentive to create really mild yet effective bleaches.

I think much of it had to do with things unrelated to longevity of the negatives, though. Environmental and safety concerns, for instance.

 

[Rudeofus]

I think much of it had to do with things unrelated to longevity of the negatives, though. Environmental and safety concerns, for instance.

Environmental concerns could have been addressed much more elegantly and economically with persulfate bleaches, but these were never brought to C-41 and E-6.

 

[RPC]

Well, since ferricyanide bleaches have never been officially tested with modern C-41 films (according to PE), all we have to go by is existing empirical evidence, which can be equally good. Take it for what you will.