Wanting to try reversal processing but also not die

mohmad khatab · Apr 18, 2020

Anon Ymous said:
I added sodium bisulfate, not sulfate. This is a substitute for sulfuric acid and works fine. Instead of using H2SO4, I used NaHSO4. This might also reduce emulsion softening from permanganate a bit, but I can't be sure about it, I haven't made any side by side tests.

Yes ,,
I understand your smart trick,
But it won't work, I think in the long run,
Sulfuric acid is essential and indispensable, and you cannot add any ingredient to replace it.
- I only read it five minutes ago, a post written by the great man Ron Murray, who said that without sulfuric acid you wouldn't get a good reverse image.
It was easier for him to say that he used sodium bisulfate and get rid of sulfuric acid.
I know you are afraid of sulfuric acid, but it is (an evil that must exist) in that formula.

Lachlan Young · Apr 18, 2020

mohmad khatab said:
Yes ,,
I understand your smart trick,
But it won't work, I think in the long run,
Sulfuric acid is essential and indispensable, and you cannot add any ingredient to replace it.
- I only read it five minutes ago, a post written by the great man Ron Murray, who said that without sulfuric acid you wouldn't get a good reverse image.
It was easier for him to say that he used sodium bisulfate and get rid of sulfuric acid.
I know you are afraid of sulfuric acid, but it is (an evil that must exist) in that formula.

In this role it is an acceptable substitute for sulphuric acid.

mohmad khatab · Apr 18, 2020

Lachlan Young said:
In this role it is an acceptable substitute for sulphuric acid.

What is the evidence for the validity of your hypothesis?
I am ready to accept Uncle Maori’s hypothesis because all formulations of whitening permanganate were never devoid of sulfuric acid at all.

Lachlan Young · Apr 18, 2020

mohmad khatab said:
What is the evidence for the validity of your hypothesis?
I am ready to accept Uncle Maori’s hypothesis because all formulations of whitening permanganate were never devoid of sulfuric acid at all.

If you have appropriate handling procedures and knowledge to work safely with it, sulfuric acid is ideal because you need a lot less of it. Bisulphate is a lot safer for average home users, although you need to use more of it. At the end of the day all you need is to get to the appropriate pH - both will do that, it's the trade-off between safety and efficiency that is the difference in this case.

Raghu Kuvempunagar · Apr 18, 2020

Mohmad,

Bisulphate is a known substitute for sulphuric acid in many formulas. This is how you do the substitution:

Gerald C Koch said:
For every gram of concentrated sulfuric acid or equivalent substitute 2.40 grams of anhydrous sodium bisulfate. If the recipe calls for concentrated sulfuric acid then 1 ml of acid weighs 1.84 grams. Therefore for 1 ml of concentrated acid substitute 4.42 grams of anhydrous sodium bisulfate.

https://www.photrio.com/forum/threa...r-sulfuric-acid-w-v-calculation-query.127462/

mohmad khatab · Apr 18, 2020

Lachlan Young said:
If you have appropriate handling procedures and knowledge to work safely with it, sulfuric acid is ideal because you need a lot less of it. Bisulphate is a lot safer for average home users, although you need to use more of it. At the end of the day all you need is to get to the appropriate pH - both will do that, it's the trade-off between safety and efficiency that is the difference in this case.

I understand well the concerns that always surround sulfuric acid, and I implicitly agree with you.
However, sulfuric acid may contribute in one way or another to prolonging the life of the bleaching solution.
- Permanganate is a very valuable element, and getting it is hard-won, so it makes no sense for me to prepare a liter and get rid of it after a week or two as a result of the sudden end of its effectiveness.!
- Therefore, I advise amateurs who are anxious about dealing with sulfuric acid to use any other bleaching solution that is inexpensive and can be prepared without the need for sulfuric acid (such as copper bleach) 100 copper sulfate + 100 sodium chloride (without iodine) half a liter of deionized water, ,, can be used for one shot and get rid of it after use, and there will be no problem. It will only cost a quarter of a dollar and a little less.

mohmad khatab · Apr 18, 2020

Raghu Kuvempunagar said:
Mohmad,

Bisulphate is a known substitute for sulphuric acid in many formulas. This is how you do the substitution:

https://www.photrio.com/forum/threa...r-sulfuric-acid-w-v-calculation-query.127462/

It will not work with the same force,
This method is called patching.
- I do not resort to patching unless you have to.
In that case - there is no rationale for me to have this patch.
Resorting to patching is not a crime, but there must be some strong justifications:
A - The high price of the chemical element (the chemical)
B - The chemical component is not completely available in the country.
Seriousness or fear is not a strong justification.
You basically decided to do chemical experiments and tests in order to prepare the formula from scratch, and this will not happen without some of the risks that you implicitly agreed upon.
Everything in life has some risks.
- If you do not accept some risks, you should buy pre-prepared chemistry from ADOX or any other company and do not trouble yourself with those adventures.

Lachlan Young · Apr 29, 2020

I have now acquired some PEG 1500 - it is definitely a solid at room temperature. I'll probably eventually get round to testing the disclosed Agfa MQ first developer formula in the next few weeks or so.

Raghu Kuvempunagar · Apr 30, 2020

Lachlan Young said:
And then check post #4 & #24 in the thread you link to.

It's an easy mistake to make when typing too fast.

I checked with Jim Noel. He did use Polyethylene Glycol for Pyrocat HD a couple of times when Propylene Glycol wasn't temporarily available to him. He didn't notice any difference in the activity of the developer.

Lachlan Young · Apr 30, 2020

Raghu Kuvempunagar said:
I checked with Jim Noel. He did use Polyethylene Glycol for Pyrocat HD a couple of times when Propylene Glycol wasn't temporarily available to him. He didn't notice any difference in the activity of the developer.

I would not be surprised by this as the preconditions necessary for the behaviour of the first developer in Scala are likely not there in working strength Pyrocat. It would have to be a pretty low molecular weight PEG compared to the one in the Scala MQ first developer to be fluid at room temperature.

It is worth remembering that Pyrocat is not as clever in its mechanisms as its proponents assume. It seems to be a set of simple direct substitutions on the core D-76 developer component relationships, which has then been modified into a non-solvent staining developer (eliminating grain solvent and buffer) with enough alkali to get it to stain reliably & deliver a moderate development time. The Scala developer is suggestive of a considerably more involved body of work on the necessary mechanism of a BW reversal first developer.

Ian Grant · Apr 30, 2020

Lachlan Young said:
It is worth remembering that Pyrocat is not as clever in its mechanisms as its proponents assume. It seems to be a set of simple direct substitutions on the core D-76 developer component relationships, which has then been modified into a non-solvent staining developer (eliminating grain solvent and buffer) with enough alkali to get it to stain reliably & deliver a moderate development time. The Scala developer is suggestive of a considerably more involved body of work on the necessary mechanism of a BW reversal first developer.

Pyrocat is essentially a newer twist on older staining developers and \Hans Windisch's Pyrocatechechin compensating developer and similar from Perutz and Mimosa etc. The idea of dilution of staining developers comes after slight changes in Rodinal in the 1930's for use with 35mm films and then Windisch etc using dilute Pyro developers for finer grain etc. So no remote relevance to D76

Ian

Lachlan Young · Apr 30, 2020

Ian Grant said:
Pyrocat is essentially newer twist on older staining developers and \Hans Windisch's Pyrocatechechin compensating developer and similar from Perutz and Mimosa etc. The idea of dilution of staining developers comes after slight changes in Rodinal in the 1930's for use with 35mm films and then Windisch etc using dilute Pyro developers for finer grain etc. So no remote relevance to D76

Ian

I'd suggest that the extent of its superadditivity relates to the ratio of the phenidone to catechol relationship which, when corrected for the metol-phenidone substitution, is exactly the same as D-76's ratio of metol to hydroquinone relationship. Arguably Pyrocat should use Dimezone-S for long term keeping properties.

Ian Grant · Apr 30, 2020

Lachlan Young said:
I'd suggest that the extent of its superadditivity relates to the ratio of the phenidone to catechol relationship which, when corrected for the metol-phenidone substitution, is exactly the same as D-76's ratio of metol to hydroquinone relationship. Arguably Pyrocat should use Dimezone-S for long term keeping properties.

Yes Dimezone developers have a reasonable shelf life however ironically much shorter than if using Phenidone, it's a Kodak marketing myth like US books saying Phenidone (powder\0 doesn't have a long shelf life, British books always stated the opposite. To be fair I've maybe not used Phenidone for as long as you I only staring to mix my own developers in1976/7 and the first two bottles Ilford batch code showed it was made in 1961, and it's still OK today although it's a couple of years since I used some as a test - I've used a lot more batches since those first two 25gm bottles.

More seriously I mix PYrocat HD using deionised water (no Glycol) and Part A keeps at least 3 years and up to 4 years with no issues, and that's in diminishing part filled bottles. I discovered this while living most of the year abroad and leaving Pyrocat here in my darkroom the UK, and later vice versa (leaving developer in Turkey). Many have noticed Ilford liquid PQ developers don't keep as long and they now except for Microphen use Dimezone, and yet the PQ developers I mix at commercial strength using Phenidone keep as well as the older Phenidone versions and longer than the current commercial products. By commercial strength I mean at a higher concentration with Sodium Carbonate substituted by Potassium Carbonate and Sodium (or Potassium) Hydroxide.

If you look at Pyrocat HD and then the Metol based Pyrocat M it's not a substitution as thePhenidone /Metol ratio should be way different, but Pyrocatechin is a fine grain developer on it's own in the right formula. I go by final results rather than just theory and I've used a lot of developers since the late 1960's although Ive always stuck to one ot two aside from testing changing rarely and only if I find a very definite improvement/advantge. So in 50 years - IDII to ADox Borax MQ, to Rodinal and Xtol, then Pyrocat HD.

Ian

Anon Ymous · Jul 14, 2020

Anon Ymous said:
On the subject of permanganate bleach, I made an observation last night. I mixed the following bleach formula in deionised water:

20g sodium hexametaphosphate
1g potassium permanganate
50g sodium bisulfate
Top up to 1000ml

My previous formula was the same, except the omission of sodium hexametaphosphate and seems to bleach fully developed film leaders in a minute or so. My previous bleach would come out of the tank with a slightly different colour. Instead of the dark purple of permanganate, it would take a more reddish, perhaps slightly brown colour. This time, the bleach with 20g/l sodium hexametaphosphate came out exactly as it was, which I believe is a good sign.

It's been almost 3 months since I made this post and I have some details to share. I processed 2 films with this bleach while it was still fairly fresh, the second was about 3 weeks after it was mixed. In both cases it performed very well and seemed fine after use. But then, life got in the way, I got too busy and haven't processed anything more, but occasionally had a look at the bleach bottle. It slowly formed a precipitate, which became pretty obvious around two months after being mixed. At about this point I filtered it through a coffee filter (see photo below for dry precipitate) and tried with a scrap film leader. Sadly, it was nowhere near as potent as it had been in the past. It didn't fully clear the film leader after 5', even at a temperature significantly higher than 20°C. So, I'm not very sure when this bleach became too weak to properly work, but perhaps some more testing can give an answer. But even if it died in a rather short time, it's not a total failure and I'll probably stick to this formula since I find it rather boring to mix it fresh every time.

Raghu Kuvempunagar · Jul 14, 2020

Anon Ymous said:
I processed 2 films with this bleach while it was still fairly fresh,

What's the capacity of fresh permanganate bleach that uses 1g per litre?

Anon Ymous · Jul 14, 2020

Raghu Kuvempunagar said:
What's the capacity of fresh permanganate bleach that uses 1g per litre?

Reasonable question, but I don't know. This thing is supposed to be used one shot, so I never bothered to check it...

138S · Jul 14, 2020

This is something we should test, we may take some fully exposed and (lights open) developed film ends... IMO the "not reuse" recommendation may be more related to over time degratation after mixing, with the not durable recipe if we keep it in the shelf.

Anon Ymous · Jul 14, 2020

Yes, the hexametaphosphate free formula is supposed to be one shot. Considering how it looks after use, I'd say it certainly is.

Lachlan Young · Jul 14, 2020

Anon Ymous said:
Yes, the hexametaphosphate free formula is supposed to be one shot. Considering how it looks after use, I'd say it certainly is.

A minimum 3 weeks life at working strength for a solution that would be getting replenished if it was in day-to-day usage isn't bad at all - especially compared to the non-hexametaphosphate containing version. There is a comparison table in one of the Agfa patents (EP1006408B1) I cited earlier that shows the extent of manganese deposit formed on the bottle walls over 42 days in column A & the extent of manganese deposit formed as a result of the bleaching process in column B. I've appended a screenshot to this post that shows how severe the difference is - the German required to understand it is minimal.

flavio81 · Jul 14, 2020

Donald Qualls said:
There's another reversal bleach that's much more innocuous than either permanganate, dichromate, or copper sulfate: hydrogen peroxide. I've seen several versions of this on YouTube; the simplest version uses drug store 3% peroxide and vinegar (stop bath should work). First develop as usual, water rinse, then thirty seconds in the acid bath and 2-3 minutes in the peroxide (at this point, you can work in the light, just transfer the spiral between two tanks or even a bowl). Repeat the acid and peroxide until the parts of the film that had been black are fully clear. By now, the undeveloped halide ought to be well exposed, so you can repeat the water rinse (to remove traces of acid and peroxide) and back into the first developer (or you can use a different developer for the redevelop, there are as many options here as there are in processing negatives). After developing, there should be no halide remaining, but if you want to be very sure, fix normally, and wash as you usually would.

No carcinogens, nothing particularly hazardous to handle. I've done reversal with dichromate bleach -- and honestly, I don't like using the stuff, it makes me paranoid knowing it's both acutely toxic and carcinogenic. Permanganate isn't much better (though it's handy to have around if you need to light a fire). The 3% peroxide from the drug store shouldn't be swallowed and needs to be kept out of your eyes -- which matches everything else in a regular black and white darkroom.

Wow Donald, you're quickly becoming my favorite forumer here.

I've long tried to follow whoever posts about experiments with the hydrogen peroxide + acetic acid bleach. There's a PDF out there on the internet that uses citric acid with success. But he uses a stronger hydrogen peroxide (8%) that I can't get anymore at drugstores today (it seems to be banned). 3% is easy to get.

However I did some tests years ago using 8% hydrogen peroxide and some acetic acid, I just soaked some developed film into it and left it. It only removed the film's image after more than 30 minutes. So this left me scracthing my head...

Or does the freshly developed, unfixed metal is much easier to bleach/remove than the final fixed image?

Kind regards,
Flavio.

Donald Qualls · Jul 14, 2020

flavio81 said:
Or does the freshly developed, unfixed metal is much easier to bleach/remove than the final fixed image?

I wouldn't think there was any difference. Silver is silver. This isn't a fast process, especially with 3% peroxide, but it will (eventually) get the job done. Most of the experimenters I've seen are in the USA, where we can order 12% peroxide from Amazon, likely even 30% (which is the strength used for bleaching hair). And that leads to a possible source -- hair salons might be able to sell you small quantities of their 30% peroxide, if they use that there.

flavio81 · Jul 14, 2020

Donald Qualls said:
I wouldn't think there was any difference. Silver is silver. This isn't a fast process, especially with 3% peroxide, but it will (eventually) get the job done. Most of the experimenters I've seen are in the USA, where we can order 12% peroxide from Amazon, likely even 30% (which is the strength used for bleaching hair). And that leads to a possible source -- hair salons might be able to sell you small quantities of their 30% peroxide, if they use that there.

I can buy hydrogen peroxide in bleaching strength, but they only sell it in rather big containers (think a few gallons). For a household with a baby, that doesn't look so good.

Still, safer than dichromate or having to deal with sulphuric acid!

I guess reversal is for twisted people...

Lachlan Young · Jul 14, 2020

@flavio81 or you could just substitute sodium bisulfate in for the sulphuric acid.

Donald Qualls · Jul 14, 2020

Lachlan Young said:
@flavio81 or you could just substitute sodium bisulfate in for the sulphuric acid.

But even without the acid, both potassium dichromate and potassium permanganate are toxic, and the dichromate is a probable carcinogen (as well as a heinous pollutant). Just having it in a house with a baby might get you examined by the authorities, and worse if it isn't under lock and key and stored in airtight containers.

But gallons of 30% peroxide for hair bleach, yet you can't buy a liter of 12% (here in the US, that strength is apparently used in gardens, I have no idea for what).

@flavio81 There is still another way out. I haven't tried it, or even seen it in video, but I'm told that silver chloride is soluble in ammonium hydroxide solution -- where other silver halides (like the bromo-iodide used in modern films) are not, so you could, in theory, bleach your developed silver with a chloride rehalogenating bleach (potassium hexacyanonferrate -- a less hazardous sounding name for potassium ferricyanide -- plus sodium chloride), then give it a bath in clear household ammonia (3% ammonium hydroxide solution). It's a common cleaner, much less hazardous than lye or battery acid; the ferricyanide is safe enough that school children in the overprotective USA get to use it to make cyanotype photograms around third grade (age 8 or so). And table salt, without iodide.

Yes, you'll want excellent ventilation -- ideally an exhaust hood immediately over the ammonia bath -- but this doesn't involve "hazardous" chemicals (and never mind that it's probably actually more hazardous for the user -- especially if they have any existing respiratory complaint -- than either peroxide bleach or permanganate/sulfuric).

Lachlan Young · Jul 14, 2020

Potassium Permanganate's LD50 is in the order of 1090 mg/kg, Potassium Dichromate is in the order of 25mg/kg. Dichromates have to carry the GHS 06 toxicity warning pictogram, Potassium Permanganate doesn't. While permanganate can stain skin, the high peroxide concentrations being talked about here are potentially corrosive (and must be labelled as such).

Both Hydrogen Peroxide and Potassium Permanganate are potentially dangerous oxidisers if wrongly handled - and at 30% concentration, hydrogen peroxide is rapidly approaching very real hazmat territory - and indeed requires licensing to buy and handle over here because of people having used it to maim and kill other humans.

Overall, it's quite obvious that the reason for the manufacturers choosing acidified permanganate for their bleaches is that if handled and stored with appropriate care and respect for the chemistry involved, it is overall less potentially harmful to the environment and the user than the alternatives. Remember that these companies will have investigated the possible choices not just from a process standpoint, but from a toxicological/ user safety perspective too.

Wanting to try reversal processing but also not die

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