Copper Sulphate B&W Reversal Bleach

[iandvaag]

Super cool -- thanks for trying this out Athril!

Gerald's formulation uses 50g CuSo4 at full strength, while the quoted Tim Rudman formula calls for 5g CuSo4 in the working strength solution. Could this tenfold disparity between formulae be the reason some have experienced softening while others have not?

Alessandro asked what the advantages a copper sulphate bleach might have over permanganate. One additional advantage I can see is that the copper sulphate bleach is stable in solution, whereas permanganate is not. This might not matter much for film, but if you want to do a longer printing session using a reversal process, this could make a difference. (In a related thought, I guess that this process would not work with azo/chloride containing emulsions, since the weak silver solvent couldn't distinguish between AgCl in the positive unexposed image and the AgCl in the bleached image.)

Also, I'm wondering, since we're making a rehal bleach, why not use ferricyanide with chloride? It might not cause the emulsion softening of permanganate bleaches (or even copper), plus it is readily available due to its use for other photographic processes. [Edit: Just saw Athril already suggested this] Normally, a rehal bleach using chloride has the problem that chloride ions cause a blixing effect, reducing density. However, in the application of reversal processing film, you normally add a silver solvent somewhere in the process anyways, to clear the highlights, so perhaps a mild blixing would be fine if the solvent effect elsewhere in the process was reduced to compensate.

Likewise, as Athril suggested, a rehal bleach using iodide normally has the deficiency of incomplete redevelopment in the shadows, but this could potentially be used to differentiate between the bleached negative and unexposed positive by developing incompletely.

This all really fascinates me, someday soon I think I'm going to try a ferricyanide bleach with NaCl and removing the bleached image with dilute ammonia (after thorough rinse of course).

Thanks also for the safety warning on ammoniacal silver solutions. The amount of ammonium is far in excess of the amount of silver (but still remains at a low concentration -- 2%), so I think Ag2O will predominate over Ag3N. Even so, I did a rough calculation of the worst case scenario and found that even if I processed 4 rolls of 120, and all of the silver of a very silver-rich (x-ray) emulsion were converted to Ag3N, 0.01 mol of Ag3N would be produced. Using the standard energy of formation of 315 kJ/mol, about 3.2 kJ (or 0.75 Calories, equivalent to the energy in about 1/10 of a potato chip) could be liberated, so I'm thinking this wouldn't be too much of a risk. Is that right?

 

[DarkroomExperimente]

gonna try this tonight:

1st dev
wash
(1) copper sulfate and sodium chloride
(2) sodium sulfite
(3) ammonia
wash
2nd dev
wash
fix
wash

any suggestions on grams/liter of the chems & times?

film will be either Tri-x or FP4+....dev will probably be HC110

 

[mrred]

A dilute permanganate rinse was once used for oral infections.

So was radium...... off point......

I look at the 3 choices as availiability issues. Permanginate is used as an explosive ingrediant. It's a big deal, here in Canada. You can get it, but the government needs you to create a paper trail (set yourself up as a corp) before venders will sell it seperately. I was lucky with Pot. Dichromate. I convinced a local chemical company to sell me some, if my order was at least $300 or more...... I bought a lot. They since have gotten sold, but I bought a lot I found the English sold Copper Sulfite willingly on EBay and I baught 500g. With a recipe similar to what Gerry posted, it never worked for me. I am still using my expensive Dichromate.

I have noticed that Permaginate is being blamed for breaking down the emulsion, and I have to disagree, as it equally happens with Dichromate. I found it's the streingth of the bleach that does the damage (likely the acid). I have been using half streingth bleach for the last 5 years with little to no emulsion loss. I just bleach a little longer.

 

[mrred]

I was going to use amonia for another formulation, a while ago. I was put off beceause of the inability to get a consistent streingth, as it evaperates out of solution quickly. I think Gerry (sorry if I was wrong here) told me I would have to use a hydromiter to accuratly mesure the specific gravity of the amonia concentration. My head started to hurt and I just nixed the project...

 

[DarkroomExperimente]

did a quick test the other day...didn't seem to work...should probably try it again sometime...however I am having fun experimenting with copper plating with the copper sulfate

 

[Athiril]

did a quick test the other day...didn't seem to work...should probably try it again sometime...however I am having fun experimenting with copper plating with the copper sulfate

Make sure you use an established working first developer and film combination that works with a normal bleach first.

I washed after sodium sulphite before ammonia solution.

 

[DarkroomExperimente]

Make sure you use an established working first developer and film combination that works with a normal bleach first.

I washed after sodium sulphite before ammonia solution.

I used Tri-x in HC110 and also used the sodium suphite step

I just used a small bit of fogged film, not a normal image, and was just looking for the film to get more clear

 

[Gerald C Koch]

So was radium...... off point......

I look at the 3 choices as availiability issues. Permanginate is used as an explosive ingrediant. It's a big deal, here in Canada. You can get it, but the government needs you to create a paper trail (set yourself up as a corp) before venders will sell it seperately. I was lucky with Pot. Dichromate. I convinced a local chemical company to sell me some, if my order was at least $300 or more...... I bought a lot. They since have gotten sold, but I bought a lot I found the English sold Copper Sulfite willingly on EBay and I baught 500g. With a recipe similar to what Gerry posted, it never worked for me. I am still using my expensive Dichromate.

I have noticed that Permaginate is being blamed for breaking down the emulsion, and I have to disagree, as it equally happens with Dichromate. I found it's the streingth of the bleach that does the damage (likely the acid). I have been using half streingth bleach for the last 5 years with little to no emulsion loss. I just bleach a little longer.

Here in the US permanganate is used to recharge water softening systems. Restricting the sale of permanganate is typical of bureaucratic muddled thinking. You can make a much better explosive from acetone and hydrogen peroxide. I would assume that neither of these chemicals is interdicted. Didn't they watch Terminator 1 where the Kyle Reese character goes shopping at a big box store and brings back the ingredients to make bombs. This is reality not fantasy, no special exotic ingredients are necessary.

Concerning copper sulfate it can be used along with acetylene gas to make a VERY shock sensitive explosive, copper acetylide.

 

[mrred]

I wound up using my copper sulfate as a root killer in my driveway. Not a total waste.

 

[Rudeofus]

You can make a much better explosive from acetone and hydrogen peroxide. I would assume that neither of these chemicals is interdicted.

I am afraid to verify your first claim, and have no intention to build such a device. I can contradict your second claim, though. People who buy unusual quantities of these compounds do generate a blip on the radar, such as this gentleman. AFAIK the existence of this compound is the main reason why we can't bring liquids through airport security any more.

 

[Gerald C Koch]

Ppermanganate is not very good for making bombs. Make a small mound of it and place a drop or two of glycerin on it. The glycerin will fizzle and catch fire but no bang. Both this and the copper acetylide are common chemistry 101 demonstrations. The acetone peroxide however is an entirely other matter. VERY dangerous and non-nitrogen based so bomb sniffing dogs cannot detect it. As I said government entities make regulations for things that they do not fully understand. Case in point here in Florida. Drain cleaner is used to make meth. Ergo if we ban the sale of drain cleaner people will not be able to make meth. Another problem solved. To hell with the poor smuck with a clogged drain. Let him hire a plumber at > $100 an hour. BTW people seem to be still making meth.

Charles Dickens skewered the idea of governments really solving problems. In Little Dorrit he describes the Circumlocution Office. I will politely refrain from making any observations as regards the event of a few days ago other than to say that the Office still carries on.

The following is a very funny but also very insightful read.

http://www.panarchy.org/dickens/circumlocution.html

 

[Rich Ullsmith]

Question: why all the noodling around with chemistry to get a reversal? Why not just contact print or enlarge onto ortho film, or even xray film?

 

[flavio81]

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)

Hi Athiril,

This post makes me very happy. However, on the steps you mention, you are not including the typical "expose the film to a bright 100 watt bulb" step. Is this correct? Do we still require re-exposure to light, as in any typical BW reversal process?

The steps you mention would be:

1. first developer (paper developer or any strong developer)
2. typical stop bath
3. copper sulphate + sodium chloride bleach
4. clearing with sodium sulphite and then wash
5. reexposure to light? are you skipping this step?
... i understand that you are carrying most steps with the lights on, but usually the reexposure to light needs to be strong
6. clearing with 2% Ammonia Hydroxide
7. redeveloping
8. (perhaps) fixing

So additional questions are...
a. How much time do you need for bleach in step (4) ? Do you raise the temperature or just use typical dev temperature (20-24°C)?
b. what happens if i skip the clearing step? (sodium sulfite is not that easy to find here)

Greetings,
Flavio.

 

[Athiril]

If you skip the clearing step you risk staining. can you Kodak Hypo Clear from a photographic reseller? That'd be fine too.

I only re-expose with room light, I dont use a dedicated bulb. Pulling it out in room light is enough to sufficiently fog the film for development (i take the film off the reel and put it back on usually).



Time.. I forgot, I prefer to raise temps to keep them short, but you'll be able to see by eye when you inspect the film.


Are there are any wine making or brewing shops? Sometimes liquor stores will carry that stuff too, you can get sodium metabisulphite there, and you can raise the pH with something if needed (not sure if an acidic pH acid clear with copper sulphate bleach would pose any issue or not).

 

[flavio81]

If you skip the clearing step you risk staining. can you Kodak Hypo Clear from a photographic reseller? That'd be fine too.

I only re-expose with room light, I dont use a dedicated bulb. Pulling it out in room light is enough to sufficiently fog the film for development (i take the film off the reel and put it back on usually).



Time.. I forgot, I prefer to raise temps to keep them short, but you'll be able to see by eye when you inspect the film.


Are there are any wine making or brewing shops? Sometimes liquor stores will carry that stuff too, you can get sodium metabisulphite there, and you can raise the pH with something if needed (not sure if an acidic pH acid clear with copper sulphate bleach would pose any issue or not).

Thanks Athiril for your response!! I do have a hypo clear product at home: "Tetenal lavaquick"

 

[Athiril]

I have no idea whether that will work or not.

 

[Rudeofus]

Thanks Athiril for your response!! I do have a hypo clear product at home: "Tetenal lavaquick"

According to Tetenal's MSDS for this product it contains Na4-EDTA and K2CO3 and has a pH of 11.2. I doesn't appear to contain Sulfite in sufficient amounts to work as step 4 clearing bath in Dan's procedure, and given its high pH it would likely precipitate Copper Carbonate, something you definitely do not want to happen.

 

[flavio81]

According to Tetenal's MSDS for this product it contains Na4-EDTA and K2CO3 and has a pH of 11.2. I doesn't appear to contain Sulfite in sufficient amounts to work as step 4 clearing bath in Dan's procedure, and given its high pH it would likely precipitate Copper Carbonate, something you definitely do not want to happen.

Thanks!!

 

[Rudeofus]

@flavio81 : When we do special purpose film processing, we need all kinds of compounds, some of which can be very hard to obtain depending on our place of residence. We may have to find substitutes, or commercial products containing whatever we need for a particular purpose. But there is one compound which is IMHO not negotiable: Sodium Sulfite. This is the red line in the sand, or whatever you want to call it. If you have any plans of self mixing photo chemistry, you need to establish a reliable and affordable supply for Sodium Sulfite. AFAIK Sodium Sulfite plays no prominent role in illicit operations (explosives, drugs, you name it), therefore it should not be overly difficult to legally obtain Sodium Sulfite from a place near you. You may also add Sodium Carbonate to that list of 'must have a local source for' compounds, but Sodium Sulfite is even more critical IMHO.

 

[RauschenOderKorn]

Sorry for reviving this older thread, but I have been researching on bleaches (and especially the differences between the various bleaches), and this thread surprised me a bit (or a lot to be honest).

In this thread, the bleaching stage for a B&W reversal process is proposed by means of a rehal bleach. According to the literature I have, this is not supposed to work and should only result in overall fogged film.

The formula quoted from Grant Haist´s book by Rudeofus contains a very small amount of bromide which probably helps keeping control of contrast and does not create significant fog. I could not access the link to Tim Rudman´s formula, but the one I know from his Lith Printing book is a rehal bleach intended for direct redevelopment and not reversing. From my understanding, reversing requires a (almost) complete & permanent removal of the developed silver after the first development while protecting the undeveloped AGhal. Any rehal bleach would not remove the developed silver, but just convert it back to AGhal. Therefore, during the second exposure the film would be fogged completely.

Has anybody made this work with a rehal bleach, if yes: which formula have you used for bleaching?

 

[Anon Ymous]

... From my understanding, reversing requires a (almost) complete & permanent removal of the developed silver after the first development while protecting the undeveloped AGhal. Any rehal bleach would not remove the developed silver, but just convert it back to AGhal. Therefore, during the second exposure the film would be fogged completely...

It seems you missed the point where an ammonia solution is used to remove the silver chloride image. Yes, it is a rehalogenating bleach, but one that turns metallic silver to AgCl. This salt is insoluble in water, but soluble in ammonia solution. Once removed, you are left with the positive image to fully expose and develop.

 

[Rudeofus]

That's the genius of Athiril's copper sulfate bleach for B&W reversal processing: it's a rehal bleach, but works with chloride instead of the more common bromide. This allows fixation with Ammonia, which will clear the Silver Chloride created by the bleach, but not the Silver Bromide/Iodide from the unexposed film grains. The Haist bleach I quoted uses Bromide, this will likely not work for reversal, but still gives Copper Sulfate amount and operating pH for such a bleach. The 0.75 g/l Potassium Bromide in Haist's bleach can likely be substituted by a few g/l Sodium Chloride, then it should work for B&W reversal.

 

[RauschenOderKorn]

Thanks for spelling it out, don't know how I missed that point.

Cool solution to the problem!

 

[NedL]

I'm glad this thread bumped up to the top again, because I remember reading it but had forgotten the details and couldn't find it again.
I want to try this idea with paper, and I have everything I need already here, so it's just a matter of finding time! ( so sometime in the next few years )

 

[Europan]

Question: why all the noodling around with chemistry to get a reversal? Why not just contact print or enlarge onto ortho film, or even xray film?

Let me answer the justified question. Reversal processing was known since the 19th century. It gained new interest with the manufacturers of motion-picture film when the giant sleeping market of home movie making was recognized. After WWI Pathé, Eastman-Kodak, Gevaert, and Agfa began making mixed-emulsion films that yield pleasing positive pictures (am I not being poetic?) by reversing. The 9½mm, 16mm, and 8mm systems (rather than mere formats) rely on that. No need of printing. Beautiful slides could be made on corresponding film, I remember well Agfa-Gevaert’s Dia-Direct.



Tonality of a reversal film can be stunning. You also have positives free from dust imprints and you don’t have to worry about good contact between negative and print stock. On the other hand exposure must be spot on whereas with the negative-positive system you can control density and contrast and colours. A printing device is necessary.

My 2 frames