Can EDTA replace PDTA in ECN-2 bleach?

[pcren1212]

Hello everyone,I recently researched ecn-2 to process movie film.In the official SR-33, SB-34, and SR-35 bleaching formulations, it can be seen that KODAK Chelating Agent No. 1 is actually PDTA.I asked the PDTA price and found it too expensive to bear,About $70 per 100 grams.I want to know if I can use EDTA instead of PDTA? What is the replacement amount?Please forgive my English grammar：）

 

[koraks]

I haven't tried it, but I'd say that it is possible but with extended bleaching time.
I myself use a ferricyanide/bromide bleach for ECN2 with sufficient rinsing before and after the bleach step. The advantages are that it's cheap and very effective. The disadvantages are the risk of dichroic fog and formation of Prussian blue (mitigated by sufficient rinsing before and after the bleach) and higher environmental impact (somewhat mitigated by the good longevity of the bleach and the potential of regeneration/replenishment).

 

[Rudeofus]

Ammonium Ferric PDTA is a much stronger bleach agent than Ammonium Ferric EDTA, and the latter needs a bleach accelerator to work in finite time frames. A direct substitution will likely not bleach to completion.

However: on page 7-32 in this H2407 document there is a very simple bleach formula based on Potassium Ferricyanate. That has to be the cheapest and simplest bleach formula imaginable, and if Kodak says "it works" then what else can you ask for? I am very sure that you can substitute the Sodium Bromide with Ammonium Bromide - the latter would actually make it faster.

 

[pcren1212]

[QUOTE =“Rudeofus，发布时间：2183891，成员：34922”] Ammonium Ferric PDTA是一种比Ammonium Ferric EDTA强得多的漂白剂，后者需要漂白促进剂才能在有限的时间范围内工作。直接替代可能不会完全消失。

However: on page 7-32 in this H2407 document there is a very simple bleach formula based on Potassium Ferricyanate. That has to be the cheapest and simplest bleach formula imaginable, and if Kodak says "it works" then what else can you ask for? I am very sure that you can substitute the Sodium Bromide with Ammonium Bromide - the latter would actually make it faster.[/QUOTE]

It is true that the formulation of potassium ferricyanide is the cheapest and chemicals are readily available.It's just not very environmentally friendly, and I am worried that the substance decomposed by potassium ferricyanide will cause harm to the human body.It's just not very environmentally friendly, and I am worried that the substance decomposed by potassium ferricyanide will cause harm to the human body.

 

[doctorpepe]

• I am posting an original review, well done, from a few years' back. It is not my review, and may have been done by Rudeofus or Photo Engineer. My apologies if this is incorrect, but my main concern is to get a source out to interested menbers.
• Overview Kodak's latest ECN-2 publication lists a color developer ingredient called AF-2000, or "Kodak Antifog AF-2000", with no explanation of what this ingredient may consist of. It took me some investigative effort to hunt down the likely composition of Kodak AF-2000: 70 g/l 3-Nitrobenzene Sulfonic Acid Sodium Salt. I would like to present the way I arrived at this conclusion, since other people may know of other and better sources of information, and some of my sources are a bit ambiguous. There is no public document I know of which provides an authoritative composition of Kodak AF-2000. If you go here, you can search Kodak for SDS of their products. If you enter "AF-2000" as "Product Name / Keyword:", it will return two products, and the SDS for United States / English will list "Substituted aromatic acid salt (proprietary)". Uh, boy, big secret here! If you ask for the SDS for Sweden / Swedish, you get an SDS which lists 3-Nitrobenzene Sulfonic Acid Sodium Salt. Concentration in both SDS says "5-10%". Now, that we know the compound in AF-2000, two questions remain: "SDS don't always list everything, so is this all?", and "5-10% is quite a range, how much is actually in there?". These questions are answered in US patent US20010046648. The ECN-2 recipe in that patent matches the official ECN-2 recipe here up to what I think are typos (26.6 g/l Na2CO3 instead of 25.5 g/l), and the patent recommends 0.30 g/l of their old AF-9. Since 0.22 g/l AF-9 are claimed to be equivalent to 0.233 g/l AF-2000, we can assume that 0.30 g/l correspond to 0.318 g/l. The Kodak ECN-2 manual asks for 5 ml/l Kodak AF-2000, therefore I would expect to find about 63.5 g/l 3-Nitrobenzene Sulfonic Acid Sodium Salt. The patent repeatedly mentions a stock solution with 70 g/l 3-Nitrobenzene Sulfonic Acid Sodium Salt, so my bets are that Kodak AF-2000 is shipped as 70 g/l 3-Nitrobenzene Sulfonic Acid Sodium Salt .

The chemical, 3-Nitrobenzene Sulfonic Acid Sodium Salt, is available from Antec in Louisville, KY. Their url is www.kyantec.com. Ask for Billy, the owner.