EDTA Bleach

mrNeil · Post by **mrNeil** » Tue Dec 05, 2006 1:49 pm

I'm using the the Fuji holographic film with a 633nm laser diode to make reflection and transmission holograms.

I'm using the JD-2 developer and bleach combination. I would like to use the widely discussed EDTA bleach, but the formulas seem to vary and the ingredients are not easily translated to non chemistry majors.

The Ferric EDTA Bleach that I'm trying to make is:

Ferric EDTA 40g

Potassium Bromide 70 g

20g Sodium hydrogen sulfate crystals( or 20cc acetic acid)

Dissolved up in 1 litre water (tap water is OK here).

I purchased:

Ferric Ammonium EDTA

Acetic Acid, Glacial, USP

Potassium Bromide, Granular, Purified

I have several questions.

1. Is this a good formula for EDTA Bleach?

2. Have I purchased the correct ingredients?

3. Can people respond with your EDTA Bleach formula?

4. Can the formula please include part numbers from their supplier?

Thank you all in advance for any help you can give.

Neil

neil@redbeetle.com

Tony · Post by **Tony** » Tue Dec 05, 2006 2:46 pm

Here's what I use:

Ferric EDTA Bleach (from Jeff Blythe)

40g Fe Sodium EDTA

60 g KBr

70cc Glacial acetic acid

Water to make 1L

I buy these from Photographer's Formulary. Works great, lasts a long time!

MichaelH · Post by **MichaelH** » Tue Dec 05, 2006 2:56 pm

fwiw what I'm using with both PFG-01 and Fuji is:

start with 800mL distilled water, warmed to ~100 deg.

Add the chemicals in the following order and make sure each is completely dissolved before adding the next.

12g Ferric Sulfate.

12g di-sodium EDTA.

30g Potassium Bromide.

50g Sodium Bisulfate.

Add distilled water to 1L.

I haven't tried Jeff's formula so can't comment on differences in results.

Tom B. · Post by **Tom B.** » Wed Dec 06, 2006 4:00 am

The original Phillips ferric EDTA bleach recipe was

30g Ferric Sulfate.

30g di-sodium EDTA.

30g Potassium Bromide.

10 ml Sulfuric acid (conc.) or substitute 50g Sodium Bisulfate

1000 cc water

I've been told that the more expensive pre-made Ferric Sodium EDTA should work better, but I was unable to notice any difference at all in the results from a cursory A/B test that I once did.

Another recipe I like is ferric Brilland bleach:

30g Ferric sulfate (should be Fe III, which is what's usually sold)

30g Citric acid (readily available in drugstores)

30g Potassium Bromide

1000 cc water

This seems to work just as well for me as EDTA does.

I don't know what effect ferric ammonium EDTA would have. Since you have some anyway why not mix a small batch to compare with ferric sodium EDTA (or the sulfate + sodium EDTA) when you eventually get some?

I should mention that I have only found ferric rehalogenating bleaches to work well with fine-grained emulsions and metol-ascorbic developer as used in the devloper part of JD-4. With JD-2 (catechol) developer, results seemed murky and inferior to results from the standard JD-2 (dichromate) bleach. But your mileage may vary. It could be that I was not sufficiently careful about rinsing in DI water before bleaching or something else I overlooked.

Martin · Post by **Martin** » Wed Dec 06, 2006 6:38 am

Tom B. wrote:I don't know what effect ferric ammonium EDTA would have. Since you have some anyway why not mix a small batch to compare with ferric sodium EDTA (or the sulfate + sodium EDTA) when you eventually get some?

I've used ferric ammonium EDTA. Though it produced an ugly slurry stuff upon mixing, the bleach was just as good as a “normal” ferric EDTA.

Martin · Post by **Martin** » Wed Dec 06, 2006 6:50 am

Forgot to mention: Ilford used to recommend a slow-acting EDTA-bleach:

Ferric sodium-EDTA.............100g

Potassium bromide...............10g

Water to make .......................1L

MichaelH · Post by **MichaelH** » Wed Dec 06, 2006 10:19 am

Tom B. wrote:I should mention that I have only found ferric rehalogenating bleaches to work well with fine-grained emulsions and metol-ascorbic developer as used in the devloper part of JD-4. With JD-2 (catechol) developer, results seemed murky and inferior to results from the standard JD-2 (dichromate) bleach. But your mileage may vary. It could be that I was not sufficiently careful about rinsing in DI water before bleaching or something else I overlooked.

It's probably also dependent on the emulsion you're using. For PFG-01 ferric edta works better than the dichromate (IMO) bleach as it doesn't remove silver form the emulsion, so no shrinkage occurs and the brightness is at least the same.

Martin · Post by **Martin** » Wed Dec 06, 2006 11:26 am

MichaelH wrote:It's probably also dependent on the emulsion you're using. For PFG-01 ferric edta works better than the dichromate (IMO) bleach as it doesn't remove silver form the emulsion, so no shrinkage occurs and the brightness is at least the same.

As a side note, the Spanish group from Alicante reported excellent results with rehalogenating dichromate bleaches. I seem to remember they tested HRT and PFG-01 emulsions. Maybe Uli could elaborate on that.