Bromide free Ferricyanide bleach?

Athiril · Feb 2, 2010

Hey APUG members,

I was wondering if I can simlpy replace sodium bromide in a ferricyanide with something else like you can in developers,

ie: Benzotriazole? or Sodium Chloride or Ammonia Chloride?

Seeing as benzotriazole and NaCl are dirt cheap for me here, and I cant find one place (pool shops and all) that sell bromide.. just bromine tablets, and Ammonia Chloride is dirt cheap as well to make.

Are there any suggestable amounts/ratios to which to replace it to?

Mike Wilde · Feb 2, 2010

My understanding on bleaching is a bit fuzzy, and no texts are handy at the moment, so I may have it all wrong.

I am pretty sure that that the K ferri becomes K ferro and thus gives up an electron.

The electron goes to the elemental silver, which becomes ionic silver, before in turn getting bound up with the available halogen ion to then become a photo sensitive compound.

Soduim bromide or pottasium bromide as you noted in a round about way are the most common halogen sources used here; it depends where you are which is cheaper, and then you adjust for the effective part of the compound (the bromide) versus the differnet molecular weight of Na or K that came along for the ride.

Silver bromide is moderately light sensitive, so by bleaching in room light all the silver bromide formed gets light stuck, and thus will develop in the next stage, when the bleached print is introduced to a developer/toner.

Silver chloride is not as light sensitive as silver brimide, so it may take more light to get the chloride all 'fogged' and ready to redevelop. I'm not sure, but it may also take UV energy to allow the silver and chloride to form.

I'm not sure how iodide would react; it is faster than bromide I believe, but has other issues.

Benzotriazole is an organic antifoggant, and will not supply any halogen ions to allow a silver halide to form if it alone is with the Ferri.

Anon Ymous · Feb 2, 2010

Mike Wilde said:
...Silver chloride is not as light sensitive as silver brimide, so it may take more light to get the chloride all 'fogged' and ready to redevelop. I'm not sure, but it may also take UV energy to allow the silver and chloride to form...

Some time ago, I asked why potassium chloride isn't used in bleaches, instead of KBr. IIRC, PE said that it's not that it won't rehalogenate silver, but it has a mild blixing effect. In other words, information in low density areas will be lost. My intention was to bleach - redevelop BW prints and that was obviously problematic. I don't know what exactly Athiril wants to do, but it might not be critical in his case.

Photo Engineer · Feb 2, 2010

Bromide is the only halogen that can be used if you wish to redevelop or preserve the original image that you had before the bleach. The Chloride ions and the Ammoniium ions turn the solution into a mild blix as stated by Anonymous. The image is bleached but also destroyed pretty much.

Benzotriazole is pretty much non-ionic and useless in this case.

PE

Marco B · Feb 2, 2010

Mike Wilde said:
Silver bromide is moderately light sensitive, so by bleaching in room light all the silver bromide formed gets light stuck, and thus will develop in the next stage, when the bleached print is introduced to a developer/toner.

As far as I know, light sensitivity has nothing to do with toning (or at least very little), I am pretty sure you can tone in complete darkness. It is just a chemical (redox) reaction in which the available silver cation (Ag+) formed during the bleaching, reacts with the redeveloper to form another substance (e.g. Ag2S in case of sepia type redeveloper).

A good document on some of the chemistry behind toners is here:

http://www.woelen.nl/photo/toner.pdf

It is about an uncommon Vanadium toner, but it discusses metal ferrocyanide toning chemistry as well, see the section "Chemistry of the toner" starting at page 8.

By the way, reading that document, Wilco refers to the possibility to have a bleach without a halogenide in it, so just ferricyanide, as in that case all of the silver is converted to a silverferri/ferrocyanide complex, which is a very yellow light to almost colorless complex. With bromide in it, a big part of the silver complexes to AgBr too.

I am not sure how well or at all it will redevelop though, and if it has any bleaching speed. However, it is interesting that the formation of silverferri/ferrocyanide complex during bleaching is often ignored in discussions here on APUG and the net. Most people just think AgBr is formed, and nothing else. However, if you've ever dumped a fully bleached print in fixer, you will notice that actually not all of the very lightly colored image is removed, as it would in case it was simply all AgBr! The latter is what fixing is based on as we all know. The remaining stuff is the silverferri/ferrocyanide complex, which is pretty stable by itself and a substance a bit similar to the prussian blue of cyanotypes. In fact, I think you can keep such a "bleached but fixed" print almost indefinetely. Here is an example that I - funny coincidence - posted yesterday:

(there was a url link here which no longer exists)

Of course, in this particular example, I did no full bleaching to retain some of the blacks, but the yellowish tone is from the remaining silverferri/ferrocyanide complex. The image was deliberately quite heavily overprinted before the bleaching, so as to have quite a lot of that light colored stuff formed and to remain in the print after the fixing.

Marco

Ian Grant · Feb 2, 2010

Yes, despite the warning above you can use Sodium Chloride in a re-halogenating bleach, it forms finer grain and so when re-developed or toned gives a lighter/warmer toned image. You can also use Potassium Iodide in a bleach bathe before toning.

Strangely Ammonia is used in some Toners and Ammonium Chloride in Intensifiers and film, as well as warm tone paper, developers, so it's worth a try with same scrap prints in a bleach for toning.

Ian

Photo Engineer · Feb 2, 2010

With NaCl in a bleach, you can lose detial in highlights and with KI, you can experience incomplete redevelopment in shadows, due to the AgI which is formed. I have experienced both effects. So, test first.

PE

Ian Grant · Feb 2, 2010

Photo Engineer said:
With NaCl in a bleach, you can lose detial in highlights and with KI, you can experience incomplete redevelopment in shadows, due to the AgI which is formed. I have experienced both effects. So, test first.

PE

With many Toners you need a denser than normal print to start with anyway, a smaller number though intensify and one uses Ammonium Chloride.
I neveer found any benefits of a KI based bleachm but an NaCl one works extremely well for warmer browner tones than a similar Bromide bleach.
So it's a case of testing as Ron says.

Ian

Anon Ymous · Feb 2, 2010

Photo Engineer said:
With NaCl in a bleach, you can lose detial in highlights...

I haven't tried bleaching with NaCl bleach, but I found a (there was a url link here which no longer exists). Assuming that the prints were identical before toning, the effect is quite obvious. Maybe snallan can elaborate on that.

Ian Grant · Feb 2, 2010

My results have always been the other way around in terms of image colour compared to the first two of Steve's, and that's how Tim Rudman and others describe it too.

Ian

Photo Engineer · Feb 2, 2010

In your reference, note the loss in detail using the NaCl bleach. It looks just like a contrast increase due to the scooping out of the highlights.

Just as I have seen.

PE

Ian Grant · Feb 2, 2010

Except that the results look the WRONG way around, a Chloride bleach gives a yellower colour and LESS contrast compared to a Bromide bleach with the same toner. Which is something I've used commercially when toning & hand colouring images in the 80's and early 90's.

Ian

Photo Engineer · Feb 2, 2010

I took the photos at face value with the explanation and they matched what I have seen in tone scale. OTOH, I did not compare them for the image color as that can be influenced by the redeveloper and by the paper type.

PE

Athiril · Feb 2, 2010

Thanks for the quality responses.

I merely ask at the frustration of a kilo of ferricyanide sitting here, and no bromide either sodium or potassium being available to buy it seems.

This is rather frustrating, its difficult to find and get simple common critical chemicals, but I can get potassium nitrate, ammonium nitrate, magnesium, aluminium powder all from the same place in bucket fulls.

In any case, it seems then ferricyanide+chloride would seem to be okay for non-redevelopment negs and colour reversals.

Edit: As per finer grain.. that is to mean to say I could pull the film out to the light, stick it in the tank, develop to maximum density, then give it a ferricyanide+chloride bleach, and re-load the film in the dark and have finer grain and slower film?

At the very least it would be interesting to shoot on a colour silver chloride film.

Marco B · Feb 3, 2010

Athiril said:
Edit: As per finer grain.. that is to mean to say I could pull the film out to the light, stick it in the tank, develop to maximum density, then give it a ferricyanide+chloride bleach, and re-load the film in the dark and have finer grain and slower film?

It seems highly impractical to me compared to switching on your computer to simply buy a package of slow speed film from the net

And I think you would lose a whole bunch of other important film characteristics determined by for example the dye sensitizers and other chemicals added by the manufacturer.

Marco

Marco B · Feb 3, 2010

Photo Engineer said:
In your reference, note the loss in detail using the NaCl bleach. It looks just like a contrast increase due to the scooping out of the highlights.

I have never used a chloride bleach, only the standard (bromide) bleach that came with my sepia toning kit, but that is an absolute huge amount of unwanted bleaching out of the highlights... I have never experienced anything like that with my bromide based bleach, and I am glad I didn't. In fact, I never have to deliberately overprint to keep my highlights. Yes, of course they are lighter because they are brown, but I do see all the detail coming back in the toner.

Marco

Ian Grant · Feb 3, 2010

Athiril said:
Edit: As per finer grain.. that is to mean to say I could pull the film out to the light, stick it in the tank, develop to maximum density, then give it a ferricyanide+chloride bleach, and re-load the film in the dark and have finer grain and slower film?

At the very least it would be interesting to shoot on a colour silver chloride film.

Athril, it doesn't work like that, you'd lose all speed and colour sensitisation, and it would give low contrast.

It's easier to just add 40g/litre Ammonium Chloride to D76/ID-11, it then gives a Super Fine Grain developer but half the film speed & needs twice the dev time, the technique was used by both Kodak & Ilford.

Alternatively add Iodide free NaCl (Common salt) instead that works well too, you'd need to experiment with the amount but 25gm/litre is a good starting point.

Ian

Athiril · Feb 3, 2010

I've used bleach before colour developer (regular EDTA stuff from Agfa) and the colour is fine, is there a significant difference between a ferricyanide-bromide and ferricyanide-chloride bleach that would remove colour sensitisation?

I've used salt in Rodinal to gain several stops of speed on colour negs as a first developer, which were then fixed, bleached, re-exposed and colour developed, bleached and fixed. Exposing slower than box speed resulted in poor results, box speed to +3 stops faster were quite good though.

I've seen some guys on one of the intensification groups using a similar technique to that except with Microphen and a ferricyanide-bromide bleach, sometimes with a mercury vapor bath before first development.

I dont really have any D-76/ID-11 to try that out with, just Rodinal and Xtol, though I have a stock of phenidone, ascorbic acid, hydroquinine, aminophenol to mix something up.

And its not easier to jump on the computer, b&w film, except GP3 and a few common others is extremely expensive, more so than Velvia, E100G and others.

Reason is, US, Thailand, Korea and China eBay sellers (real shipping costs) dont stock/sell it - which is where I usually get my film from, can get some bargains at $6-7 per roll for most colour stuff in 120.

Freestyle and all the others start at US$40 shipping, the local supplier (about 2500km away) that actually has that kind of film charge about $18 for domestic shipping, and they charge about $13/roll for 120 b&w stuff.

I've pulled colour up to 14 stops when I didnt have NDs via use of first developer and other techniques etc.

Ian Grant · Feb 3, 2010

If the bleach is just for colour work prior to fixing Salt, NaCl, will work perfectly well.

Ian

Athiril · Feb 3, 2010

Your 40 g/L of Ammonium Chloride suggestion, is that to concentrate or working solution?

Ian Grant · Feb 3, 2010

Athiril said:
Your 40 g/L of Ammonium Chloride suggestion, is that to concentrate or working solution?

Yes, it was Crabtree suggestion at Kodak in the early 30's, Ilford were still suggesting it in the mid 60's.

Ian

Athiril · Feb 3, 2010

Sorry I meant, is that to the concentrate, or to a working solution, like 1+3, 1+6, 1+9 etc?

Ian Grant · Feb 3, 2010

Sorry, to the concentrate.

Ian

Marco B · Feb 3, 2010

Athiril said:
I've pulled colour up to 14 stops when I didnt have NDs via use of first developer and other techniques etc.

:confused: Eh, 14 stops, that isn't 10 to many? I think we would like to see some results of that!

Athiril · Feb 3, 2010

Marco B said:
:confused: Eh, 14 stops, that isn't 10 to many? I think we would like to see some results of that!

No, when you have a b&w first developer, you can do as much as you want up to the point of when you form a visible b&w negative via the light itself.

Here is the example, the pull is worth around 14 stops, the exposure was only +10 stops though.

Bromide free Ferricyanide bleach?

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