Ferric Ammonium EDTA / Disodium EDTA?

Oscar Brown · Jan 23, 2017

I have been interested in making my own c-41 and ra-4 chemicals for a while now, but I'm only just started to get back around to it using the recipes from http://www.bonavolta.ch/hobby/en/photo/c41_ra4_chemicals.htm
One thing that has stumped me, is what is Ferric Ammonium EDTA? And where can I buy it in Australia (or overseas as long as it can be shipped here) without it costing an arm and a leg.
For whatever reason, my shopping list which i created months ago, lists Disodium EDTA as i think an alternative, is that the case? Or did i just write that down for whatever reason. If it is an alternative, where can i also get Disodium EDTA?
Any help is much appreciated for an amateur
Cheers,
Oscar

dE fENDER · Jan 23, 2017

Oscar Brown said:
I have been interested in making my own c-41 and ra-4 chemicals for a while now, but I'm only just started to get back around to it using the recipes from http://www.bonavolta.ch/hobby/en/photo/c41_ra4_chemicals.htm
One thing that has stumped me, is what is Ferric Ammonium EDTA?

It's one of the salts of EDTA (A means acid). A critical component of the color bleach.

Oscar Brown said:
And where can I buy it in Australia (or overseas as long as it can be shipped here) without it costing an arm and a leg.
For whatever reason, my shopping list which i created months ago, lists Disodium EDTA as i think an alternative, is that the case? Or did i just write that down for whatever reason. If it is an alternative, where can i also get Disodium EDTA?
Any help is much appreciated for an amateur
Cheers,
Oscar

You can use Ferric-Ammonium or Ferric salt, but Disodium salt has no ability to dissolve metallic silver. You may try to prepare it by yourself, using one of this recipes:
1. Ferric-Ammonium salt from EDTA (not salt): (there was a url link here which no longer exists)
2. Ferric salt from EDTA Disodium: dissolve 200g EDTA Disodium in 800 ml hot water. Then add 160 g FeCl3 * 6H20. Boil the mix while 1/6 part is left then put it to dry for a week in enamel/glass tray.

Photo Engineer · Jan 23, 2017

Here, for the first time, is my original blix, which became the RA4 blix.

Water 800 ml
Sodium Ferric EDTA 45 g (Purchasable at many places that supply chemicals)
Sodium Sulfite 10g
Ammonium Hypo (60% solution) 100 ml
Tetra Sodium EDTA 5 g
Dilute to 1L

pH 6.5 at 20C.

In some cases, you can substitute the following if you cannot get Sodium Ferric EDTA

Water 800 ml
NaOH 40% 26 ml
EDTA (free acid) 40 g
Ferric Chloride (FeCl3 . 6 H2O) 12 g
Sodium Sulfite 15 g
Sodium Hypo 150g
Water to 1L

pH 4.7 for paper.

This latter is very much slower. Take care adding the EDTA to the NaOH solution.

I will not vouch for image stability using either one.

PE

Halford · Jan 26, 2017

FWIW EDTA stands for ethylene-diamine-tetraacetic acid. It is a chelating agent, which is to say it's an organic compound that 'wraps around' a biggish metal ion like FeIII and reduces its tendency to react with anything else in the surrounding matrix and, for example, form insoluble hydroxides. If you take an iron supplement it will usually be listed on the ingredient list as 'iron chelate' -- and is generally an EDTA complex like sodium ferric EDTA (You find it included in fertilizers / hydroponics media for the same reason). Also if you need treatment for heavy metal poisoning that is often done by injecting you with a bunch of EDTA to sequester the heavy metal ions and keep them from disrupting your nerve cell membranes etc.

So it's a really common chemical that you'll find from most any chemical supplier, though not typically from your local hardware store.

Rudeofus · Jan 26, 2017

You can use Sodium Ferric EDTA maybe for RA-4 as shown by PhotoEngineer, but I doubt it will properly bleach C-41 film. Due to its orange mask it will be hard to detect even egregiously incomplete bleaching.

If you can't get either EDTA free acid or Ammonium Ferric EDTA in Australia, there is a procedure for making EDTA free acid from EDTA Disodium Salt:

Dissolve as much Na2-EDTA as possible in tap water. Solubility tables state something about 100g/l, in my experience you will get a bit less
pour about 800ml of this solution into a beaker which can hold 1l or more
add concentrated mineral acid, e.g. battery acid, muriatic acid, whatever you can get your (gloved) hands on
EDTA free acid will form as white powdery precipitate, allow it to settle
Pour out the clear liquid on top into some container for hazmat
set up a funnel with a coffee filter, and filter the remaining liquid with the EDTA free acid powder
Use deionized water to wash the filtrate. Don't wash too much, since EDTA is sparingly soluble in water.
Dry the filtrate, then crush it into little chunks

With this method you should be able to obtain about 50-60 grams of EDTA free base, repeat or scale down at will to match your needs.

In order to turn this into Ammonium Ferric EDTA you need to do the following:

Calculate how much Ammonium Ferric EDTA you need for your task
Calculate how much EDTA free acid and how much Ferric ion this is equivalent to
Calculate how much ferric salt (Ferric Nitrate, Ferric Sulfate, Ferric Cloride) this is equivalent to
Add 3-5 % to the calculated EDTA amount
Add that amount of EDTA into a beaker, fill with water up to 80% of required volume (or less of your ferric salt is too dilute)
Add the ferric salt. The EDTA will not dissolve yet, don't worry.
While vigorously stirring, slowly add Ammonia until all the EDTA is dissolved. Add some extra Ammonia to make sure you don't precipitate EDTA if another acid is added later. If you have a pH meter, try to get at or above pH 4.5.

Photo Engineer · Jan 26, 2017

It turns out that the method outlined for making Ammonium Ferric EDTA does not work as well as desired. It can be done but not very well. We had to use Ferric Oxide and Ammonia gas with EDTA at high pressure and temps with some water to just dissolve the ingredients.

PE

Rudeofus · Jan 27, 2017

Photo Engineer said:
It turns out that the method outlined for making Ammonium Ferric EDTA does not work as well as desired. It can be done but not very well. We had to use Ferric Oxide and Ammonia gas with EDTA at high pressure and temps with some water to just dissolve the ingredients.

It has worked very well for me, and the resulting mixture of Ammonium Ferric EDTA and Ammonium Nitrate, together with Ammonium Bromide and a suitable bleach accelerator does a great job bleaching my slide film. I have used Ferric Nitrate Nonahydrate as source of Ferric ion, but will try the much more available Ferric Chloride soon. Some Ferric Oxide precipitates while I add Ammonia, but it dissolves within a few minutes. Funny thing is that the resulting mixture very closely resembles the bleach from (there was a url link here which no longer exists).

Obviously Ferric Oxide would work just as well, if one can find a good source for it. I would, however, strictly advise against using gaseous Ammonia outside special facilities, not to mention the combination of high pressure and high temperature.

Anon Ymous · Jan 27, 2017

Rudeofus said:
...Obviously Ferric Oxide would work just as well, if one can find a good source for it...

Ferric hydroxide is practically a hydrated form of ferric oxide. You can probably precipitate it from ferric chloride by reacting it with a hydroxide. NaOH should be fine, the resulting salt is very soluble. Ferric chloride is a pcb etchant and can be easily sourced (in the hexahydrate form IIRC).

Murray Kelly · Jan 27, 2017

Oscar Brown said:
I have been interested in making my own c-41 and ra-4 chemicals for a while now, but I'm only just started to get back around to it using the recipes from http://www.bonavolta.ch/hobby/en/photo/c41_ra4_chemicals.htm
One thing that has stumped me, is what is Ferric Ammonium EDTA? And where can I buy it in Australia (or overseas as long as it can be shipped here) without it costing an arm and a leg.
For whatever reason, my shopping list which i created months ago, lists Disodium EDTA as i think an alternative, is that the case? Or did i just write that down for whatever reason. If it is an alternative, where can i also get Disodium EDTA?
Any help is much appreciated for an amateur
Cheers,
Oscar

Oscar, I know exactly how you feel. I bought a 1L kit to experiment with and stuffed up the bleach. After a lot of looking I ended up the KodacolorII rehalogenating bleach.

Iron chealate 100g Bunnings garden section)
KBr 50g Vanbar when they have it back in stock
Cloudy Ammonia 6ml Bunnings cleaning section
Water to 1L
(the end product is meant to be that awful colour)

To adjust pH (~6) I used pool lowering chems (Bunnings again) as either HCl or Sod. Bisulphate. You won't need much.
While you are at it pick up a tub of Borax to adjust the pH meter. It is Monohydrate in Oz. 1 pinch in 10ml. Very scientific.

Scales are cheap on the 'net as you doubtless know, but not everything needs the accuracy of the developer mix.

If you want to go down the Ferric chloride path Alltronics still stock it In my old books IIRC ferric chloride and oxalic acid (Bunnings) make a fair bleach but cannot comment on its usefulness in C-41.

I retreat into the bunker.

Photo Engineer · Jan 27, 2017

Rudi, it works, but does not give the pure compound. It carries along the extra ions such as nitrate, chloride and etc.

PE

Rudeofus · Jan 27, 2017

Photo Engineer said:
Rudi, it works, but does not give the pure compound. It carries along the extra ions such as nitrate, chloride and etc.

I don't know about the chloride, but the nitrate definitely doesn't hurt. See my above comment:

Rudeofus said:
Funny thing is that the resulting mixture very closely resembles the bleach from (there was a url link here which no longer exists).

I will definitely try the Ferric Chloride at some point in time, since that's the compound which I can get by far most easily. Ferric Oxide shouldn't be too difficult either, Keten has it listed for 10€/kg.

Photo Engineer · Jan 27, 2017

E6 does not use a stop and does use HQMS-K. So, these recipes are not "exact" and may not work well with all films.

As for the extra salts such as Nitrate and Chloride, they work for E6 but are not used for C41. That is all I can say now.

PE

RPC · Jan 27, 2017

Oscar Brown said:
I have been interested in making my own c-41 and ra-4 chemicals for a while now, but I'm only just started to get back around to it using the recipes from http://www.bonavolta.ch/hobby/en/photo/c41_ra4_chemicals.htm
One thing that has stumped me, is what is Ferric Ammonium EDTA? And where can I buy it in Australia (or overseas as long as it can be shipped here) without it costing an arm and a leg.
For whatever reason, my shopping list which i created months ago, lists Disodium EDTA as i think an alternative, is that the case? Or did i just write that down for whatever reason. If it is an alternative, where can i also get Disodium EDTA?
Any help is much appreciated for an amateur
Cheers,
Oscar

Search APUG and you will find better formulas, particularly C-41 developers, than at the link given.

Rudeofus · Jan 27, 2017

Photo Engineer said:
As for the extra salts such as Nitrate and Chloride, they work for E6 but are not used for C41.

Modern C-41 process uses Ammonium Ferric PDTA, not EDTA. I mix my Ammonium Ferric PDTA from Ferric Nitrate, PDTA and Ammonia, any my bleach does its job. Since Ammonium Ferric PDTA is a stronger oxidizer than Ammonium Ferric EDTA, and the Ammonium Ferric PDTA based bleach is much more dilute, the extra Ammonium Nitrate in my concoction should hurt much less than in E6 bleach (less ionic strength to begin with).

Photo Engineer · Jan 27, 2017

Rudi, I know that PDTA is used. It gives a stronger bleaching action compared to the old EDTA, and by using home made EDTA bleaching is slower. Bleaching is so hard that modern films need the activity. In fact, bleach accelerators are added to the films to assist.

So, unless you can get the developed silver in a Dmax area below about 1 - 3 mg / ft square, your image will be adversely affected. This is why I suggest using the 6 - 8 min bleach and then fix times with films if an EDTA bleach is used.

PE

Ferric Ammonium EDTA / Disodium EDTA?

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