Bleach blend recipes for rehalogenating paper for toning and lith?

1kgcoffee · Nov 9, 2017

I'm interested in mixing up some of my own bleaches for toning and lith, mostly with Moersch and arista products.

My understanding is that there is silver bromide, chloride and iodide, each with special characteristics. I would like to mix some combination of these for deep rehalogenation of papers that I will then tone or lith.

Wondering what recipes you guys use? The most common is ferricyanide and potassium bromide. But could I also use potassium bromide and iodide and copper chloride together in one solution? What characteristics will these produce in the final image? Will they react or be unstable in solution? My knowledge of chemistry is severely lacking here.

Thanks in advance,
1kgcoffee

adelorenzo · Nov 9, 2017

For bleach I use:

Pot. Ferri. 50g
Pot. Bromide 10g
Sodium Carbonate 20g
Water to make 1 L

This is the formula from the Photographer's Formulary sepia toning kits. It also works well for me with other toners, lith, and for general reduction of prints (followed by fixer).

Gerald C Koch · Nov 9, 2017

The amount of rehalogenation cannot be more than the original silver content of the image. Ex nihilo nihil fit. In other words you cannot create something from nothing.

For the purpose of rehalogenation for toning it is pointless to use anything except potassium bromide.

1kgcoffee · Nov 9, 2017

about that.. if you rehalogenate from reduced silver to silver iodide or chloride instead of silver bromide, won't it affect the tonal qualities after redevelop or toning? I thought this is what makes up the character of the paper (type of halogens)

Rudeofus · Nov 10, 2017

Silver Iodide is much, much more insoluble than Silver Bromide, which is again much, much more insoluble than Silver Chloride. If you mix a bleach with equal amounts of Potassium Bromide and Potassium Iodide (plus the other stuff which goes in there), you will get 99.9 - 100 % Silver Iodide. That's likely why you haven't seen bleaches with a mix of halides. Note: emulsion makers intentionally do mix halides, but they have strict process control and equipment completely out of range to us amateurs.

Similar stuff happens if you mix bleach agent: the stronger one will dominate the bleach and the weaker one will just sit around. Neither Ferricyanide nor Copper are particularly attached to Silver, so you won't get superadditivity like MQ or PQ developers either.

There are/were toner kits which offer(ed) a variety of halide concentrates for mixing different bleaches with different toning results, so I am not sure whether Bromide is all one needs.

Anon Ymous · Nov 10, 2017

Rudeofus said:
... There are/were toner kits which offer(ed) a variety of halide concentrates for mixing different bleaches with different toning results, so I am not sure whether Bromide is all one needs.

I've asked this question in the past and the answer I got was that different halides will give different results, with chloride giving warmer tones. My question didn't involve mixing different halides in the same bleach though, and the explanation you gave involving solubility of silver halides makes sense. Apart from that, I remember Kodak selling two different sepia toners, both of them having a ferricyanide - bromide bleach and a sodium sulfide redeveloper. One was supposed to be warmer (I only used one of them) and the only difference I could spot when checking their MSDS was the ferricyanide/bromide ratio. I haven't tried this route, perhaps it's worth a try?

Rudeofus · Nov 10, 2017

MSDS doesn't show all the ingredients. If the "warmer" sulfide toner contains small amounts of strong but non-toxic silver solvent, it won't show up in MSDS yet give different results.

That's also a likely explanation, why Chloride bleach gives warmer results: high amounts of Chloride in bleach will form soluble [AgCl3]-- or [AgCl4]--- complex ions, thereby reducing amount of silver available for redevelopment/toning, which in turn gives warmer tones.

PS: it won't help if you mix copious amounts of Chloride into a bleach with Bromide, the Bromide will quickly precipitate all silver ions from these chloride complexes.

Anon Ymous · Nov 10, 2017

Rudeofus said:
PS: it won't help if you mix copious amounts of Chloride into a bleach with Bromide, the Bromide will quickly precipitate all silver ions from these chloride complexes.

Yes, until whatever bromide is added is used up. From this point on, it will likely change behavior.

Ian Grant · Nov 10, 2017

The ratio of Ferricyanide to Halide (usually Bromide) also affects the way the bleach works as can the addition of Carbonate. It's best to experiment.

Ian

M Carter · Nov 10, 2017

Here's one. Experiment with it, it can sort of "posterize" a print in strong dilutions. Usually comes back fine when redeveloping. can produce warmer tones in redevelopment.

BTW, when toning and you find you lose your most delicate highs - very dilute paper developer can bring them back, but it may change the toning color. Adding a bit of potassium bromide can add some warmth and slow it down more. If you first tone in lith developer or variable toner (or whatever) you need to wash the first-pass toner from the print before going on to the paper dev. Just another thing to experiment with.

If you plan on bleach and tone, it can be wise to add a half stop or so to your highs, or flash the paper to add an overall layer of barely visible fog - gives the bleach something to eat.

For copper bleach, I was able to mail order a small bottle of 48% sulfuric acid, i think from the Formulary - I did have to fill out the govt. paperwork though.

COPPER SULFATE BLEACH

Copper (Cupric) Sulfate..................................50 g
48% Sulfuric Acid (EXTREME CARE!)..............13ml
OR
Concentrated Sulfuric Acid (EXTREME CARE!)..............6.5 ml
Sodium Chloride (Common Salt)........................... 50 g
Water to make..........................................1000 ml

If you want to avoid concentrated acid (96%) use 13ml of 48% sulphuric acid instead.

IMPORTANT NOTE: Always add strong acids to water slowly and NOT water to acid. This formula makes a stock solution that is diluted 1+9 with water for tray use. The stock has a very long shelf life and the diluted working solution will bleach around 3-4 10×12″ prints before exhaustion.
Bleaching should be carried out on a thoroughly fixed and washed print. The use of hypo clearing agent after an initial wash, followed by further washing, is recommended.
Bleaching is initially slow at this 10% dilution, but suddenly proceeds rapidly. Using this dilution enables more control should only partial bleaching be required.

Rudeofus · Nov 10, 2017

I wonder whether such a Copper Sulfate bleach can not be reformulated with Sodium Bisulfate. The latter comes in powder form and it much easier/cheaper to ship. Even if that won't work at all, it is still easier to obtain Sulfuric Acid in 37% (aka battery acid) or 15% (even less hazard when mixing with water) concentrations than as 48% or higher.

Photo Engineer · Nov 10, 2017

With any acidic Sulfate bleach, you run the risk of losing Silver imagewise and making Silver Sulfate which dissolves. This is the reason that reversal B&W processes use an acidic Sulfate bleach, in order to remove the negative silver image. So, be careful.

Mixes of halides are ok in making emulsions, and can alter image tone, but in a rehal bleach for toning, again it is questionable as to the effect you would get.

PE

adelorenzo · Nov 10, 2017

Hi Ian,

Ian Grant said:
The ratio of Ferricyanide to Halide (usually Bromide) also affects the way the bleach works as can the addition of Carbonate. It's best to experiment.

As I mentioned above I am using 20g/L carbonate which I understand is optional as I have also mixed bleaches with only ferri and bromide. I am curious, what is the role of the carbonate in this situation?

Ian Grant · Nov 10, 2017

adelorenzo said:
Hi Ian,
As I mentioned above I am using 20g/L carbonate which I understand is optional as I have also mixed bleaches with only ferri and bromide. I am curious, what is the role of the carbonate in this situation?

It's not something I've really thought about, Agfa published 4 bleaches and 4 toners and the combinations could allow a lot of control in terms of colour.

One bleach uses Carbonate another Ammonia, it's about controlling the grain size of the re-halogenated halides. I've always used a plain Ferricyanide-Bromide or sometimes Chloride bleach as I have plenty of control with my actual toners, but for use for Lith work it may well be worth playing around more with the various bleaches.

Ian

adelorenzo · Nov 10, 2017

Ian Grant said:
It's not something I've really thought about, Agfa published 4 bleaches and 4 toners and the combinations could allow a lot of control in terms of colour.

One bleach uses Carbonate another Ammonia, it's about controlling the grain size of the re-halogenated halides. I've always used a plain Ferricyanide-Bromide or sometimes Chloride bleach as I have plenty of control with my actual toners, but for use for Lith work it may well be worth playing around more with the various bleaches.

I didn't think much about it either, I just started adding the carbonate based on the recipe that comes with the Formulary sepia kits. Maybe I'll try some experimentation to see if it has any impact on the final result.

Ian Grant · Nov 11, 2017

adelorenzo said:
For bleach I use:

Pot. Ferri. 50g
Pot. Bromide 10g
Sodium Carbonate 20g
Water to make 1 L

This is the formula from the Photographer's Formulary sepia toning kits. It also works well for me with other toners, lith, and for general reduction of prints (followed by fixer).

That is the Agfa 503 re-halogenating bleach. The great thing about the Agfa formulae is they are made up from stock 10% solutions so you mix which ever you want each time.

Ian

Doremus Scudder · Nov 11, 2017

I'm curious as to the role the carbonate plays in the rehalogenating bleach. I've always used simply ferricyanide and bromide for my rehalogenating purposes.

Best,

Doremus

Ian Grant · Nov 11, 2017

Doremus Scudder said:
I'm curious as to the role the carbonate plays in the rehalogenating bleach. I've always used simply ferricyanide and bromide for my rehalogenating purposes.

Best,

Doremus

All I can find is a reference that adding Sodium Carbonate or Ammonia to the bleach gives deeper (as in darker) and colder tones. My Agaf book just lists the 4 bleaches with no comments.

Agfa 501 is essentially the same as 503 without the Carbonate Same ratio/dilution of Ferricyanide/bromide). I should have better information somewhere in my darkroom library

Ian

Ian Grant · Nov 11, 2017

Now we can also add a different shift in terms of pH by adding Nitric acid to the bleach which is done in Dupont 6-T Varigram toner in the CB-3 bleach, this gives the coldest result despite using Sodium Chloride instead of Bromide.

Some bleaches add Ammonium Carbonate.

Ian

1kgcoffee · Nov 11, 2017

Thanks so much guys, this helps huge!

Going to do some experimenting...

Marco Buonocore · Nov 14, 2017

Doremus Scudder said:
I'm curious as to the role the carbonate plays in the rehalogenating bleach. I've always used simply ferricyanide and bromide for my rehalogenating purposes.

Best,

Doremus

I tried the formula above with the sodium carbonate added, and consistently got an unpleasant overall yellow staining. This was with Ilford and Agfa fibre papers. Under the same fixing and washing conditions , I had no problems with a plain ferricyanide and potassium bromide bleach.

This was a few years ago, but looking over my notes from the time, adding the sodium carbonate to the mix didn't bring me any joy at all.

Bleach blend recipes for rehalogenating paper for toning and lith?

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