Copper Sulphate B&W Reversal Bleach

Athiril · Jun 8, 2016

Something I've thought about but only finally gotten around to trying, looks like it was successful on the very first try. This avoids the damage and unreliability of Permanganate, and the toxicity of Dichromate (And the difficult some people have of getting their hands on it).

I used my standard developer recipe for T-Max reversal on some Delta 100 as a first developer, wash etc.

Then I used a copper sulphate and sodium chloride bleach.. a rehal bleach. The idea here to bleach the negative portion back to silver chloride so that we can selective fix the silver chloride and leave the rest of the silver bromide and silver iodide intact.

I cleared the bleach with sodium sulphite and washed the film.

Then I sat the film in undiluted store bought household cloudy ammonia which is 2% Ammonia Hydroxide.. we can take advantage of the solubility difference in weak ammonia solutions between the silver halides..

Then I just washed and redeveloped in some print developer. Worked like a charm.

The important part here is you use sodium chloride and not a bromide salt, and also that you follow it up with an ammonia bath.

(Keep in mind I've only done the 1 test)

Developed Negative:

Bleached Negative:

After Ammonia and Re-Developing:

Gerald C Koch · Jun 8, 2016

I have only used a copper sulfate-sodium chloride bleach once many years ago. It caused severe softening of the emulsion. There was frilling showing that the emulsion was separating from the base layer. My advice would be for thorough testing with a number of films.

DarkroomExperimente · Jun 8, 2016

very interesting...where do you get the copper sulphate?

I might have to try this

EdoNork · Jun 9, 2016

Copper sulfate is added to tomato plants. So it will be readily available on farm supplies stores (sorry, I don't know the correct English term).

sfaber17 · Jun 9, 2016

Fantastic idea! Impressive.

Rudeofus · Jun 9, 2016

I really like this! Any suggestions whether this AgCl fixer could be made from Ammonium Chloride instead of smelly Ammonia?

Also, when I looked at Copper Sulfate bleach for E6 film some time ago, it worked fine but left a tiny reddish stain behind. Can you detect something similar on these B&W slides?

DarkroomExperimente · Jun 9, 2016

how much copper sulfate/NaCl ? and for how long...I gotta try this...I loved BW reversal back in the day

Rudeofus · Jun 9, 2016

This thread mentions a Copper Sulfate based bleach presented in Grant Haist's book. Boiling this formula down to 1l working solution gives you:
12g Copper Sulfate (presumably the pentahydrate)
15g Citric Acid (presumably the monohydrate, but probably won't matter)
0.75g Potassium Bromide
3g Sodium Hydroxide
water ---> 1l

For the purpose of regular B&W reversal one would replace the 0.75g Potassium Bromide by a few grams of Sodium Chloride.

PS: Tim Rudman's book also appears to contain a Copper Sulfate bleach recipe, this one uses Sodium Chloride from the onset.

Gerald C Koch · Jun 9, 2016

One recipe that I have which states its use for reversal processing is

Copper sulfate 50 g
Sodium chloride 50 g
Water to make 1 l

Use FS

BTW the common name for copper sulfate is copperas or "blue stone." It might be easier to find under this name.

DarkroomExperimente · Jun 9, 2016

Gerald C Koch said:
One recipe that I have which states its use for reversal processing is

Copper sulfate 50 g
Sodium chloride 50 g

Use FS

BTW the common name for copper sulfate is copperas or "blue stone." It might be easier to find under this name.

is this 50g per liter? and what is "FS" ? thanks

(btw you saved me about $25 today...I almost bought a chemical to test...but in my heard I heard your voice and PE's screaming "NO...check the K-P rule first")

Gerald C Koch · Jun 9, 2016

Sorry every once and awhile my computer gets busy doing other things and drops characters and full lines of input.

The formula is for 1 liter. The solution can be used again and again.

There is also

Water 750 ml
Copper sulfate 10 g
Concentrated sulfuric acid 20 ml
Water to maker 1 l

Use FS. (full strength)

Gerald C Koch · Jun 9, 2016

Glad to hear that the K-P has been helpful.

DarkroomExperimente · Jun 9, 2016

well I hope it works great 'cause I just ordered a pound from Photoformulary...if not I can always use it to make pretty blue crystals or practice electroplating...

Gerald C Koch · Jun 9, 2016

DarkroomExperimente said:
well I hope it works great 'cause I just ordered a pound from Photoformulary...if not I can always use it to make pretty blue crystals or practice electroplating...

You can always use it to make Bordeaux mixture for black spot on your rose plants.

Rudeofus · Jun 10, 2016

Alessandro Serrao said:
permanganate is not much more toxic than copper, much less than chromates...
So why not use it?

it contains lots of oxygen which it freely dispenses to any compound willing to take it on, which means it could soon end up on the "you can't get it here" list
it softens gelatin, which means some film stock is incompatible with bleaches made from permanganate

Gerald C Koch · Jun 10, 2016

A dilute permanganate rinse was once used for oral infections.

Manganese is an interesting element as it is in column VIIB of the periodic table which means that its chemistry sometimes mimics that of chlorine and the other halogens which are in column VIIA. Both elements form a heptoxide Cl2O7 and Mn2O7 which are the anhydrides of perchloric and permanganic acids. These are oily liquids that are shock sensitive explosives. Chlorine heptoxide is colorless but manganese heptoxide is brownish green forming a violet vapor when heated. So now you know what the letters mean beside the column numbers in the table.

Athiril · Jun 13, 2016

I've never has a copper sulphate bleach damage film. I have with permanganate every time.

You just need a rehalogenating bleach, so ferricyanide bleach with sodium chloride should work. I haven't tried it though.

You want to bleach all the developed negative to silver chloride then use that AgCl selective fixer (ammonia) to remove it.

Athiril · Jun 13, 2016

I eyeballed the amounts as I didn't think it'd matter since it's to completion, unless it converted some of the AgBr to AgCl which would be a problem. I also bleached in quite warm/hot water and just inspected until it was done. Which was quite quick.

Ammonia was room temp, and inspected until done.

You'll also probably want to test this side by side with a dichromate bleach or successful permanganate bleach to check the quality holds up. I've only done the 1 test.

It also might be possible to bleach the negative to AgI usingan iodide salt in the bleach, clear the bleach then develop the film and pull it when the positive is developed and fix the AgI off using normal fixer (guessing it may develop orders of magnitude slower than the rear od the emulsion and would not develop in the time the rest of the emulsion does)

sfaber17 · Jun 13, 2016

Gerald C Koch said:
Manganese is an interesting element as it is in column VIIB of the periodic table which means that its chemistry sometimes mimics that of chlorine and the other halogens which are in column VIIA. So now you know what the letters mean beside the column numbers in the table.

Nice. Seems like this is something that is missed in most Chemistry courses.

DarkroomExperimente · Jun 13, 2016

so does this sound close to what you did:

Copper sulfate 50 g
Sodium chloride 50 g
1 liter water

maybe 5 minutes or so?

Rudeofus · Jun 13, 2016

You can try this easily without sacrificing precious shots. Develop a test clip in broad daylight until it is completely black, then watch it in dim daylight as you bleach it back. If you wash and fix the bleached clip, you can see how much silver was left and adjust bleach time accordingly. One or two tests should at least get you into the ball park.

sfaber17 · Jun 13, 2016

Be careful with ammoniacal silver solutions since they form explosive silver compounds such as an ammonia silver oxide. This maybe too dilute to worry about, but if you let it set and evaporate... I'm thinking if you neutralize it with stop bath and add fixer, you would be OK

Athiril · Jun 14, 2016

Alessandro Serrao said:
There should be no silver left so the fix isn't necessary.
I will say that also permanganate doesn't ruin any emulsion as long as it's used at 18°C and its concentration is halved in relation to the Ilford pdf.
This way I've succesfully reversed all eFKe and Foma films without the slightest damage.
I'm also considering the fact that every reversak kit uses permanganate and not copper sulfate so there must be a valid point to do this.
I'll stick with it.

Ammonia won't remove any undeveloped silver iodide however. A fix it shouldn't hurt it.

Rudeofus · Jun 14, 2016

Alessandro Serrao said:
There should be no silver left so the fix isn't necessary.

DarkroomExperimente's suggested bleach is a rehal bleach. I recommended the fixer, because silver halides have this milky appearance which may hide retained metallic silver.

Alessandro Serrao said:
I will say that also permanganate doesn't ruin any emulsion as long as it's used at 18°C and its concentration is halved in relation to the Ilford pdf.
This way I've succesfully reversed all eFKe and Foma films without the slightest damage.
I'm also considering the fact that every reversak kit uses permanganate and not copper sulfate so there must be a valid point to do this.
I'll stick with it.

I have a tiny container of Permanganate, and this container has a very specific warning label on it that freaks out people. Potassium Nitrate is/was a popular fertilizer and used by the metric ton, yet a trained chemist with decades of Kodak experience, whom we all know and value here at APUG, can't buy it to build a salt bridge for pH measurements. I would therefore conclude my statement with "use whatever works for you, but don't act surprised when you suddenly can't buy it any longer".

DarkroomExperimente · Jun 17, 2016

has anyone been experimenting with this?

my copper sulfate just arrived in the mail...gonna try it soon

Copper Sulphate B&W Reversal Bleach

Privacy & Transparency

Privacy & Transparency