Copper Sulphate B&W Reversal Bleach

Anon Ymous said:

I just tried the copper sulfate bleach, followed by an ammonia and an ammonium chloride bath, with some Retro 80S, Delta 100 and HP5 Plus pieces of already developed film.

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@Anon Ymous: just curious to know if these pieces of film developed with a reversal first developer? Or with normal B&W negative developers? If it's the latter then these pieces might or might not have a high enough density to test a reversal bleach.

@Raghu Kuvempunagar Delta 100 and HP5+ were developed in Xtol. Retro 80S was reversal processed and it certainly was very dense.

Raghu Kuvempunagar said:

@Anon Ymous: just curious to know if these pieces of film developed with a reversal first developer? Or with normal B&W negative developers? If it's the latter then these pieces might or might not have a high enough density to test a reversal bleach.

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I don't know what Anon tried, but a lot of my testing is not with reversal first developer. However, I did test with my full reversal setup here: https://www.photrio.com/forum/threads/copper-sulphate-b-w-reversal-bleach.137943/page-4#post-2416390 and Ilford Delta 100 clears in 5 mins @ 19C for me. It's possible a bit more density could be achieved there: I fixed first since I was testing the bleach and not the developer time.

EDIT: @Anon Ymous posted at the same time answering that

@relistan Thanks for the further explanation, understood!

Raghu Kuvempunagar said:

I'm interested in knowing the longevity of this bleach as compared to Rudman's Copper Sulphate bleach which has a very long shelf life. I'll keep the bleach stored for a month and revisit it.

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@relistan: I tested the bleach today on a scrap negative. It worked well except it was marginally slower than before. Cheers!

Raghu Kuvempunagar said:

@relistan: I tested the bleach today on a scrap negative. It worked well except it was marginally slower than before. Cheers!

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Hey good to know. So that’s what, almost a month so far?

Finally gave it a try: Adorama VCRC pinhole paper negative ( about a 5 minute exposure of an oak tree ), post-flashed. Developed as usual in LPD, negative looked very nice. Acetic acid stop for about 30s then wash. Bleached with 5g copper sulfate, 5g salt, and 1g CA in 100 ml water... bleach was fast... appeared to be done in less than 45s, I left it for 90 seconds. Rinsed a couple times, then I poured in enough household ammonia to cover it... ( I think household ammonia is around 5% ammonium hydroxide, but the bottle does not say ). I didn't know how long this step should take, so I put it in a box and stuck it outside for 20 minutes. Then I poured off the ammonia and treated it with some saturated salt solution.

At this stage there was about a 1/2 or 3/4 inch strip on each end of the paper that had printed out... it had a nice dark purple-grey color and stronger than usual printout for adorama paper ( I make lumen prints and retina prints and have a good sense of how this paper behaves when prints out ). It had been inside a box in the shade, so not much light, but the ammonia fumes must have really helped it along. ( I was surprised how much it printed out... silver chloride alone would not print out that strongly with that little amount of light.. silver bromide fumed with ammonia must be pretty darned fast! ) The printout was reversal, and the part of the image I could see looked nice. I can only guess that the paper curled and these two ends were above the shallow ammonia. Now in light, I could see that the bleached areas had a light yellow color, and the areas of the negative that were originally white were still white.

Anyway, I washed it, and redeveloped in light, and the printed out areas turned black/grey normal color for developed paper, but the rest of the paper that had been under the ammonia didn't do anything at all. I stopped and fixed and washed and it's hanging to dry right now.

My conclusion is that maybe it sat in the ammonia for too long and managed to remove the silver bromide? Definitely good strong reversal on the two end strips that ( presumably ) weren't immersed the whole time. I have another negative to try, and I'll try a much shorter ammonia bath next time, just a minute or two. Probably tomorrow. I'll also see if sulfite will remove the yellow at this stage.

All in all, even if this works well, it's fussy compared to using H2O2 + CA bleach... on the other hand, the printed out section looked kinda cool.. so I want to know more about that and if maybe I could take that further. More later!

Silver Bromide is also soluble in Ammonia but dissolves much slower than Silver Chloride. 20 minutes in 5% Ammonia is a little too long. 2 minutes in 2% clears all Silver Chloride and up to 5 minutes does no harm.

Raghu Kuvempunagar said:

20 minutes in 5% Ammonia is a little too long. 2 minutes in 2% clears all Silver Chloride and up to 5 minutes does no harm.

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Excellent. Thank you!

relistan said:

Hey good to know. So that’s what, almost a month so far?

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Yes, almost a month. Good thing is no precipitate formed.

BTW I managed to get hold of Copper Chloride from a lab. Initial impression is very positive. pH of aqueous Copper Chloride solution is ~3.5, i.e. acidic, and hence addition of an acid is not necessary for it to function as a bleach. And no need to add Sodium Chloride either. Will use it in reversal when the weather gets a little better.

Raghu Kuvempunagar said:

2 minutes in 2% clears all Silver Chloride and up to 5 minutes does no harm.

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That did the trick. Today's try worked just fine. Good strong blacks after 2nd development, so there must have been plenty of silver bromide left. So, I got this working just fine with paper negatives.

Differences from yesterday:

• I didn't bother washing after first stop in acetic acid, just drained and poured in the CuSO4 solution.
• Used the same 100ml of CuSO4 from yesterday and it seemed just as fast.
• I used less ammonia, poured in just a little, put a tray cover on, and gently rocked the tray for 90s.

After the ammonia step I brought it into the light, washed, and then develop/stop/fix/wash

Two observations:.

1. I did not see the same strong printing out like I saw yesterday. After the ammonia step, but before rinsing, I even let it sit in bright light for a little while to see what would happen... the silver bromide areas slowly turned a light lavender color, with some hints of orange in some areas, but pretty much just like what would happen if you take a piece of fresh photopaper and put in in the light. Nothing dramatic and certainly nothing like what I saw yesterday. I think being in the box with the ammonia ( being fumed ) must have had a lot to do with what I saw yesterday.
2. Twice now I've had the impression that as soon as I added strong salt solution to the ammonia discard, the strong ammonia smell disappeared. I didn't stick my nose in it to really test, but I wonder if that impression is right.

Still todo: I didn't test using sodium sulfite to clear the yellow cast. With H2O2 + CA bleaching, I found that using very weak pot ferri followed by hypo ( like Farmer's reducer ) removed the yellow cast and makes the image "pop"... I'll see about both of these approaches later.

Today's negative wasn't nearly as good a photograph as yesterday's, but it proved the process works. I'll post a digi-snap of it later if I don't mess it up trying the sulfite and/or reducer.

I'm off now with my re-loaded coffee can cameras to make some more negatives to play with

Small update. On fully processed and dried paper, I couldn't clear the yellow/orange color with sodium sulfite, or I mean, a 5% solution made no visible difference after 30 minutes. If you use sodium sulfite to clear, it might be important to do it right after the bleach step and before additional processing. A very weak Farmer's reducer removed the yellow/orange color and left pure white, without noticeably affecting the image. I used about 0.2% pot ferri for about 30 seconds, then another 30 seconds or so in 4 or 5% sodium thiosulfate. That left the lights pure white, with no yellow or orange remaining.

NedL said:

Twice now I've had the impression that as soon as I added strong salt solution to the ammonia discard, the strong ammonia smell disappeared. I didn't stick my nose in it to really test, but I wonder if that impression is right.

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Depending on the pH, you might well be correct. If you add sodium chloride to an ammonium hydroxide solution, you'll get a equilibrium between that pair and (odorless) sodium hydroxide plus ammonium chloride. If the equilibrium goes far enough toward ammonium chloride, the odor will drop right off.

That yellow-orange color you report was most likely silver grains of a size to show that color (i.e. a very, very warm tone). You should be able to avoid that color by avoiding excessive white light exposure after bleaching. You want enough to fully expose the silver bromide left after the ammonia bath, but not enough to make it print out. Likely that level will be a matter of seconds in full room light. Or, as you noted, Farmer's Reducer removes it because the finest silver gets dissolved before the bigger grains (which we see as black) shrink enough to notice.

Donald I think you're right about the yellow/orange. I didn't mention it, but I did notice that when I first took it out of the ammonia, the visible yellow image was quite faint.. it strengthened after exposed to light, as you guessed. I had an ulterior motive for exposing it to lots of light, because I was curious about the strong print-out I saw yesterday. I'm still curious about that and it's got me thinking about some other directions this process might go in

Here it is. Not a good photograph and not a good negative, but it shows the process worked. There is some mottling that I've also seen with H202 bleached paper negatives when exposed to light and redeveloped... but not so much when redeveloped in thiourea.

@NedL: congratulations!

If you use Sodium Sulphite clearing bath right after the bleach step and in darkness or highly subdued light, there shouldn't be yellow coloration. Maybe Sulphite solubilizes the finest grain halides which give the warm tone.

Today I tried using the sodium sulfite right after the bleach ( and before the ammonia -- and still under safelight ) and it did indeed clear. Under my dark red safelight, I could just barely see the light yellow image on the paper, and the sulfite bath removed it, and there was no hint of color or any faint visible image after the ammonia bath when I brought it into the light.

The final result, after 2nd development, has a very subtle salmon-colored cast in some of the highlights. The brightest highlights are white, but this color makes the upper highlights look slightly dingy. I think ( if it was a good enough photograph to care about! ) it would still benefit from just a touch of reducer. This color cast is so subtle that you might not notice it on film... but you can see it against the white paper if you look carefully.

Oh, and the saturated salt solution definitely does make the ammonia discard stop smelling

NedL said:

The final result, after 2nd development, has a very subtle salmon-colored cast in some of the highlights. The brightest highlights are white, but this color makes the upper highlights look slightly dingy. I think ( if it was a good enough photograph to care about! ) it would still benefit from just a touch of reducer. This color cast is so subtle that you might not notice it on film... but you can see it against the white paper if you look carefully.

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Something similar happens sometimes when using dichromate bleach. Best explanation I could find was that the dichromate bleach leaves a weakly light sensitive chromium-silver deposit in the gelatin which gets developed after light exposure and second development. When developed, the deposit gives the highlights a light yellow or yellow-brown tint. Haist says the tint is generally observed with poorly formulated and/or excessively reused dichromate bleach. I wonder if there is an analogous copper-silver deposit formation in your case which is exacerbated by light exposure.

That's interesting. It would have to be something insoluble in both sodium citrate and insoluble in ammonia.
I guess since Haist mentioned poorly formulated or reused bleach, there's a possible analogy there too: this was the 3rd time I reused the same 100ml of CuSO4 bleach... I'll try to remember to look for it again when I make fresh bleach.

Haist quotes Miller, Russel and Crabtree: "The extent of staining rises with the pH of the bleaching, and the pH increases with exhaustion. Therefore, frequent replacement of the bleach, or its revival by the addition of a little sulfuric acid, is helpful in lessening stain troubles." This is, of course, in the context of dichromate bleach.

NedL said:

That's interesting. It would have to be something insoluble in both sodium citrate and insoluble in ammonia.

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i wondered about this as well. But all the bleaches I’ve messed with needed a clearing bath. The result without one varies from yellow staining to darker than expected results.

Hello all,
This is my first post on this forum, hope it is OK (and sorry for bumping this thread).

I've just tried out a copper chloride bleach (I use it for etching circuit boards). With Tri-X reversal (Kodak 7266), it produced a good image, however my ammonia turned very bright blue, and I am not quite sure how this occurred. Might it have been because I was worried about insufficient bleaching (probably not a concern, I bleached initially for 3 minutes) and bleached the film twice?

With 7266 I have had permanganate bleaches completely strip the emulsion (following the second dev), but no such problem occurs with Cu chloride bleach. I will try the bleach with Foma R100 at some future point.

A question: I made the Cu chloride by first mixing H2O2 and HCl, and then dissolving Cu metal in that solution. Could that potentially have impacted the working of the bleach?

aussiedev said:

g this thread).

I've just tried out a copper chloride bleach (I use it for etching circuit boards). With Tri-X reversal (Kodak 7266), it produced a good image, however my ammonia turned very bright blue, and I am not quite sure how this occurred.

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Did you wash the film in water after bleaching followed by a clearing bath in Sodium Sulphite solution?

aussiedev said:

my ammonia turned very bright blue, and I am not quite sure how this occurred.

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This is due to carry-over of a small amount of copper chloride solution into the ammonia, which then forms a copper amido complex. Be careful, this blue stuff is potentially explosive if allowed to dry to crystals (but like most other photo chemicals, will degrade quickly in the environment of a sewer or septic, at least in small quantity).

Raghu Kuvempunagar said:

Did you wash the film in water after bleaching followed by a clearing bath in Sodium Sulphite solution?

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First bleaching - washing between chloride and ammonia, followed by sodium metabisulfite clearing bath (normally I would do it between but I forgot). Second (unnecessary) bleaching - no/less washing and no clearing bath (hence the carry-over of the chloride). There is no yellow stain on the film which is why I think the second bleach was unnecessary.

Also I am using cloudy ammonia because where I live clear stuff is unavailable, no apparent change to how well it works but I did wash extra carefully after the ammonia to remove the soap.

aussiedev said:

First bleaching - washing between chloride and ammonia, followed by sodium metabisulfite clearing bath (normally I would do it between but I forgot).

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If you skipped the clearing step between bleach and ammonia steps, then it's probably carry over as Donald suspected.