B&W Reversal with Hydrogen Peroxide

[relistan]

Thanks, yes..........Oh I see I forgot to actually specify the dev, I used HC-110 dilution B all the way here.
I have a bunch of Acros 100 as well, so I may pluck one of those and shoot a test-roll tomorrow.
Not sure if the Hydrogen-peroxide + vinegar solution is still active though, it has been sitting in a closed bottle for a week, crossing fingers. (it's expensive here, €25 for 500ml).

Yes, he uses HC-110B in the video. I have been using Ilford Multigrade and that has been great. As for bleach age... I have some a month old that works great. It has been in a clear glass jar but stored in the dark. I would expect months of life unless you exhaust the peroxide from use.

It takes about 3 minutes for the original formula. With 0.08g/L silver nitrate it takes about 7 minutes to completely bleach my test strip.

Ah, not too bad, though. 7 minmutes is OK. Did the bleaching action work just as well?

 

[Helinophoto]

Ok, so I tried this again, this time with Acros 100.
After bleach, just like with the Tri-x, it looked quite similar to the Foma, it is milky with a faint positive (when looking through it, against the light).

But, after exposing it pretty aggressively to a halogen light and then developing again, I saw that the film turned darker and darker and darker really quick over a 5 minute period.
- No discoloration.

The Hydrogenperoxide solution is still very much active (dropped a piece of film in it and it was fizzing like crazy).

There were reversed images on the film, but the film was really dark/too dark and turning darker almost visible to the eye.

Does this indicate insufficient bleaching, perhaps? (I did it for about 10 minutes and nothing was fizzing or anything like that at that point).
Too much secondary light??

I will try one more time, as long as the bleach is active.
This time I will bleach, then rinse the film several times and try to bleach it again, to see if there is something that is building up and blocking further/complete bleaching to happen.

If that doesn't work, I think I will abandon this process, because it is not easy to debug the process very well.

Interesting though.

 

[relistan]

Does this indicate insufficient bleaching, perhaps? (I did it for about 10 minutes and nothing was fizzing or anything like that at that point).
Too much secondary light??

Interesting, will be good to see how Acros works with it. You bleached long enough. Did the whole image turn sold dark or just not a good slide?

Too dark is usually either not long enough in the first developer (this is my guess) or the first developer needs a bit of a boost, either from a development accelerator or from a solvent. If you have sodium thiosulfate, try 1 gram of that as a starting point. This bleach does enough fixing that adding too much will usually screw up your film. As for re-exposure, there is a broad plateau of the right amount of time. But 5 minutes is definitely way too long. I am not quite sure what the effect will be but I remember in Haist's book he said there is a pretty wide window that is good but outside that produces bad results. I do about 30 secs - 1 minute. And it is bleached in the light so it gets some exposure there as well.

 

[relistan]

I tried an experiment today that looks very promising! No staining, good times, clear bleaching. This was with ORWO N75.

This is the bleach that is looking promising:

• Hydrogen Peroxide 3% — 20ml
• EDTA free acid — 0.5g
• Sodium bicarbonate added a bit at a time until the EDTA dissolves. pH finishes at about 7-8. Guessing it's a few grams. I just targeted the pH.
  
• Citric acid to pH 4. Guessing like 0.5-1g. Again I just targeted the pH.
• Bleaching to completion 7.5 mins @ 25C!

I will try to get better precision measurements tomorrow but this is the best thing I've tried in the last few weeks. It's not from a patent, it's my attempt to do what made sense to me from all the reading and research. I will look at the emulsion damage in a loupe in the morning.

EDIT: cc @kentanghk

 

[Helinophoto]

Interesting, will be good to see how Acros works with it. You bleached long enough. Did the whole image turn sold dark or just not a good slide?

Too dark is usually either not long enough in the first developer (this is my guess) or the first developer needs a bit of a boost, either from a development accelerator or from a solvent. If you have sodium thiosulfate, try 1 gram of that as a starting point. This bleach does enough fixing that adding too much will usually screw up your film. As for re-exposure, there is a broad plateau of the right amount of time. But 5 minutes is definitely way too long. I am not quite sure what the effect will be but I remember in Haist's book he said there is a pretty wide window that is good but outside that produces bad results. I do about 30 secs - 1 minute. And it is bleached in the light so it gets some exposure there as well.

Only 30 - 60 seconds on the redevelopment?
Wow...ok.....I just followed the recipe on the youtube video, he ran it for 5.
I reuse the HC-100B solution for the second developer, so I suppose it is a little weaker, but still.....wow, ok I will try to go way less time on the second developer indeed.
My theory was, that if the bleach actually removed what it was suposed to, a lot of the film should be blank and not turn black, you see.

The film had many "good" frames, which then turned to black, overall. If I had continued, the whole film would be solid black, most likely. (no difference between borders or the images themselves)
I don't have sodium triosulfate, unfortunately. All chemicals are either very difficult to get hold of (only sells large quantities), or are very expensive (pharmacy) or on some kind of "banned chemicals" list, because it can be used for bombs etc.

It is really sad, because I really would have wanted to try wet collodion at some point, but if I started to order what I need from abroad, I would quickly find myself in a conversation with the intelligence-services.

 

[relistan]

Only 30 - 60 seconds on the redevelopment?

Sorry! No I thought you were talking about reexposure! Redevelopment is definitely minutes. 5 might be a little short even. Sorry for the confusion.

 

[relistan]

My theory was, that if the bleach actually removed what it was suposed to, a lot of the film should be blank and not turn black, you see.

But the image looked good when fully bleached? I am not sure what went wrong. Sounds like it rehalogenated, but I don't see how. The most likely possibility is still that it didn't develop hard/long enough in the first developer and what you are seeing the the residual silver developing.

I don't have sodium triosulfate, unfortunately. All chemicals are either very difficult to get hold of (only sells large quantities), or are very expensive (pharmacy) or on some kind of "banned chemicals" list, because it can be used for bombs etc.

It is really sad, because I really would have wanted to try wet collodion at some point, but if I started to order what I need from abroad, I would quickly find myself in a conversation with the intelligence-services.

Can you buy regular non-rapid fixer anywhere? That is generally mostly sodium thiosulfate. You might be able to use a few millileters of that instead. The easiest first thing to do is just develop longer in the first developer as the next step.

 

[YoIaMoNwater]

Ok, so I tried this again, this time with Acros 100.
After bleach, just like with the Tri-x, it looked quite similar to the Foma, it is milky with a faint positive (when looking through it, against the light).

But, after exposing it pretty aggressively to a halogen light and then developing again, I saw that the film turned darker and darker and darker really quick over a 5 minute period.
- No discoloration.

The Hydrogenperoxide solution is still very much active (dropped a piece of film in it and it was fizzing like crazy).

There were reversed images on the film, but the film was really dark/too dark and turning darker almost visible to the eye.

Does this indicate insufficient bleaching, perhaps? (I did it for about 10 minutes and nothing was fizzing or anything like that at that point).
Too much secondary light??

I will try one more time, as long as the bleach is active.
This time I will bleach, then rinse the film several times and try to bleach it again, to see if there is something that is building up and blocking further/complete bleaching to happen.

If that doesn't work, I think I will abandon this process, because it is not easy to debug the process very well.

Interesting though.

I had issues with TMax400 for reversal and also got dark slides. Like @relistan said, it definitely need a silver solvent or stronger/faster 1st developer. I've tried reversal with TMax400 @ 1600 in 1.x3X Microphoen with permanganate bleach, the result slide was very dark. From what I read, Tri-X also has similar issues since the new emulsion is different than before.

Films that work great in reversal are Rollei Superpan 200/Retro 400 @200 and Fomapan 400 @800 with permanganate bleach. I suspect H2O2 bleach could also work.

 

[Helinophoto]

I had issues with TMax400 for reversal and also got dark slides. Like @relistan said, it definitely need a silver solvent or stronger/faster 1st developer. I've tried reversal with TMax400 @ 1600 in 1.x3X Microphoen with permanganate bleach, the result slide was very dark. From what I read, Tri-X also has similar issues since the new emulsion is different than before.

Films that work great in reversal are Rollei Superpan 200/Retro 400 @200 and Fomapan 400 @800 with permanganate bleach. I suspect H2O2 bleach could also work.

Thanks for the info so far, I understand that the second dev should go for about 5 minutes, re-exposure about 30-60 seconds. ^^

Ok, can different developer do the trick?
I have some d-76
And Rodinal (unless it is the type that is dead on me, need to check that one).
I also have a few Fuji Super Prodol packs that I normally use with my Neopan 1600 films.
I have Ilford Perceptol

For paper, I use LPD dev in various concentrations.

For fix, I have some Fomafix, powder
I also have some Rapid fixer from Ilford, but it has started to smell bad, it works, but it is getting a bit iffy.
And I have Tetenal Variofix.

The only acids I have, is ascorbic acid (used for caffenol).

But I have no PH measurement-tool.

Initially, I added 35ml of the 7% white vinegar solution to my 500ml 3% Hydrogenperoxide

The normal development time for Acros in HC-110B is around 5 minutes, so running it for 15 minutes is quite a push, normally, but it may be the "wrong" developer perhaps?

 

[relistan]

Thanks for the info so far, I understand that the second dev should go for about 5 minutes, re-exposure about 30-60 seconds. ^^

Ok, can different developer do the trick?
...
For paper, I use LPD dev in various concentrations.

For first developer, I'd use LPD at the strongest normal ratio, and run it for about 10-12 minutes at 20C. See where that lands you. If that doesn't work, you could try D-76 with some washing soda (sodium carbonate) added to force the hydroquinone into action. Start with 60g monohydrate or (if I didn't screw up the math) 135g of the crystals (decahydrate). This is what Hans Dietrich used in his D-76-based first developer.

For fix, I have some Fomafix, powder
I also have some Rapid fixer from Ilford, but it has started to smell bad, it works, but it is getting a bit iffy.
And I have Tetenal Variofix.

All of these appear to be rapid fixers and probably aren't going to be the right thing to add to the first developer. There are various accelerators you could use instead, but they are going to be even harder to get than sodium thiosulfate or thiocyanate solvents. I'd recommend trying to get ahold of either some sodium thiosulfate or a non-rapid fixer if you can't get the raw chemical.

But I have no PH measurement-tool.

Me, neither, but I have a little packet of cheap pH testing paper.

The normal development time for Acros in HC-110B is around 5 minutes, so running it for 15 minutes is quite a push, normally, but it may be the "wrong" developer perhaps?

Yeah, you often end up with a lot longer dev time or much stronger developer in this process than in regular development. Try the longer time, it might work.

For testing, I'd recommend that you start with some really short rolls (like 5 frames at -2 -1 0 +1 +2 stops exposure). This will prevent wasting a lot of film and will help identify the right exposure for the developer combo you are using. Obviously this really only works with 35mm where you can cut it short in the camera.

 

[Donald Qualls]

You can buy sodium thiosulfate pentahydrate (the slippery, rice-shaped crystals) at pool and spa supply stores, sold as a chlorine reducer. They don't put ingredients on the can/bucket any more, but ask to see the Safety Data Sheet (what we used to call MSDS); it'll say something like "sodium thiosulfate penahydrate 98-100%" -- or ask them to open a bucket, the crystals are very distinctive. If it's fine grained like table salt or beach sand, it's still useful for photography (just not so much in your first dev); that will be sodium sulfite.

 

[relistan]

I did some further experimentation today with the EDTA/Citric acid bleach. I tried various mixtures and various pH to see how that affected things. Here are some observations:

Emulsion Damage

• So far I have not seen any blistering on ORWO N75 or Fomapan 400. Fomapan 400 doesn't show any even on the more aggressive bleach, though.

pH

• As described in several of the patents, pH has a big effect on bleaching performance. It appears that you can use the pH to control bleaching performance.
  
• The bleaching speed also seems to have a big effect on staining. The very fast chain reaction that sometimes happens seems to leave bad staining. Raising or lowering the pH seems to help. The bad chain reaction seems much more likely around pH 5.5.
  
• pH around 7 took about 15 minutes at 20C and was very even and clear, no staining
  
• pH around 5.5 took about 5 minutes at 20C and both stained, and unevenly bleached
  
• pH around 4 took about 10 minutes at 20C and was reasonably even and clear, no staining

Bubbling as an Indicator

• If the bleach is working well, there is a slow, steady release of bubbles from the surface of the film
• If it is bubbling heavily, something is probably not right, and staining or emulsion damage will likely result.

Temperature

• Seems to have less of an effect on speed and staining than pH. It does have some effect.
  
• Raising the temperature can get the reaction started sooner, but seems not to speed up the whole bleach time in the same proportion for some reason. It also risks worse staining and uneven bleaching.
• Somewhere about 25-30C is probably the sweet spot. 20C works fine.

General Observations

• I am so far unable to clear the leader in the same way with this bleach that I was with the acetic acid/peroxide bleach. I suspect this is because this bleach is not also a BLIX. I will try to run it on some fixed film to see if that makes it run totally clear.
• The amount of EDTA I am using seems quite high. I will try to back it down to much less.
• Today I found that the total _amount_ of citric acid, bicarbonate, and EDTA appears not to be significant. It seems to be the ratio and pH that makes the most difference. I am sure some minimum amount is needed, but after that it seems to not matter. I was able to use the same bleach and just dial the pH up and down with citric acid and bicarbonate to no ill effect that I can detect.

Here's the measurements I started out with today:

• Hydrogen Peroxide 3% — 20 ml
  
• EDTA free acid — 0.5g
• Sodium bicarbonate — 1g
• Citric acid (pure) — 0.5g
• pH about 4

I was not able to replicate quite the bleaching performance I got yesterday, though yesterday's bleach still worked today. I then upped the amount of EDTA to 1g total and sodium bicarbonate to 2g total and citric acid to 1g total. I believe I could have maintained these ratios but used less of all of these.

Here are some photos of what it looks like bleached, and then how dark it was after redevelopment. Since this film had not been fully fixed, I am guessing the lack of fixing action in the bleach accounts for that. I will try with fixed film.

 

[kentanghk]

Ah, not too bad, though. 7 minmutes is OK. Did the bleaching action work just as well?

The bleached film strips look identical to my eyes.

I did some further experimentation today with the EDTA/Citric acid bleach. I tried various mixtures and various pH to see how that affected things.
View attachment 264566

This bleach looks promising! I suppose your result provides more evidence on the bleach-fixing action of acetic acid bleach, Maybe a stronger first developer will fix the darkening issue in second development? I add sodium carbonate to my HC110 first developer and the film does not darken in second developer.

The fact that you have a working bleach formula without silver salt is really encouraging.

 

[relistan]

Well, we have a good, working bleach! I ran it on a little slip of ADOX Silvermax/Scala 160 to see how it does with blistering. It runs a bit fast so I am unsure if this will work any better than the acetic acid bleach. I can slow it down by adjusting pH if needed. But this works great so far with Fomapan 400 and I do not see any blistering.

• Hydrogen Peroxide 3% — 20 ml
• EDTA free acid — 0.8g
• Sodium bicarbonate — 1.3g
• Heated to 30C and stirred until bubbling stops and everything is dissolved
  
• Citric acid — to pH about 4.5 . This is 0.5-0.8g but not sure the actual amount. Added bit by bit to target pH
• 6 mins @ 20C

My belief here is that the EDTA is doing most of the work to drive the reaction in the right direction and that the citric acid is there only to stabilize the peroxide and complex some of the silver into silver citrate. You can run the bleach without any citric acid. You need about 2g of EDTA, though, and it leaves bad staining. Running citric acid by itself is unusably slow as @kentanghk showed.

When this bleach is done, I found that if you go straight to the second developer, you get a perfectly even yellow stain across the film. This is different from the dark staining we have seen before. I thought about Ricardo Leite's citric acid/9% peroxide bleach and decided this is probably sliver citrate. Using a sulfite clearing bath at 20g/L for 1 minute clears the stain completely, leaving a perfectly clear frame. Ricardo's citric acid bleach does not.

I need to try to do some chemistry calculations to figure out how much citric acid should really be added. Not sure I'll be able to manage that without just trying a bunch of times. @YoIaMoNwater or @kentanghk is that something you might be able to help calculate?

EDIT: Well, while it seems to work great with other films... it does not (at this pH anyway) prevent blistering on ADOX Silvermax. I won't have time for awhile, but will eventually try to run a higher pH and see how that does with Silvermax.

 

[relistan]

@kentanghk I wonder if a sulfite clearing bath would clean up all the yellow staining on your citric acid/silver nitrate bleach?

 

[YoIaMoNwater]

Well, we have a good, working bleach! I ran it on a little slip of ADOX Silvermax/Scala 160 to see how it does with blistering. It runs a bit fast so I am unsure if this will work any better than the acetic acid bleach. I can slow it down by adjusting pH if needed. But this works great so far with Fomapan 400 and I do not see any blistering.

• Hydrogen Peroxide 3% — 20 ml
• EDTA free acid — 0.8g
• Sodium bicarbonate — 1.3g
• Heated to 30C and stirred until bubbling stops and everything is dissolved
  
• Citric acid — to pH about 4.5 . This is 0.5-0.8g but not sure the actual amount. Added bit by bit to target pH
• 6 mins @ 20C

My belief here is that the EDTA is doing most of the work to drive the reaction in the right direction and that the citric acid is there only to stabilize the peroxide and complex some of the silver into silver citrate. You can run the bleach without any citric acid. You need about 2g of EDTA, though, and it leaves bad staining. Running citric acid by itself is unusably slow as @kentanghk showed.

When this bleach is done, I found that if you go straight to the second developer, you get a perfectly even yellow stain across the film. This is different from the dark staining we have seen before. I thought about Ricardo Leite's citric acid/9% peroxide bleach and decided this is probably sliver citrate. Using a sulfite clearing bath at 20g/L for 1 minute clears the stain completely, leaving a perfectly clear frame. Ricardo's citric acid bleach does not.

I need to try to do some chemistry calculations to figure out how much citric acid should really be added. Not sure I'll be able to manage that without just trying a bunch of times. @YoIaMoNwater or @kentanghk is that something you might be able to help calculate?

View attachment 264657

EDIT: Well, while it seems to work great with other films... it does not (at this pH anyway) prevent blistering on ADOX Silvermax. I won't have time for awhile, but will eventually try to run a higher pH and see how that does with Silvermax.

Looks good! Interesting that Fomapan 400 works nicely for reversal, I'm not sure why the company itself doesn't promote it. Anyway, what calculation are you trying to do?

 

[Donald Qualls]

Looks good! Interesting that Fomapan 400 works nicely for reversal, I'm not sure why the company itself doesn't promote it. Anyway, what calculation are you trying to do?

In 35mm, it has a gray base (similar to that on Tri-X), so the Dmin on slides would be higher than desirable. Kodak has never recommended Tri-X still film for reversal processing, either.

 

[relistan]

Looks good! Interesting that Fomapan 400 works nicely for reversal, I'm not sure why the company itself doesn't promote it. Anyway, what calculation are you trying to do?

Thanks! As @Donald Qualls said, it has a gray base (clear in 120). I am using it for testing because I had a ton of it I bought accidentally at one point when I meant to buy Arista Premium 400 (Tri-X) and instead bought Arista.EDU 400 (Fomapan 400). So, it's good for experimenting. And it turns out the emulsion is super forgiving of peroxide bleaches...

What I'm trying to calculate is the right amount of the ingredients in a more precise way. I know what I measured works, but I'd like to see if I'm adding too much of something or not quite enough of something else. I know that I don't have 100% purity, but it seems like I ought to be able to say:

• it takes roughly X amount of sodium bicarbonate (or NaOH) to get all of the EDTA dissolved
• it takes roughly Y amount of citric acid to get the pH back to 4.5

I know my measurements are in the right ball park, but it would be good to make sure this is right.

Sticking with sodium bicarbonate because the stuff I have seems clean, it's cheap and easy to get, I can calculate the sodium bicarbonate and citric acid part. (I think)

C6H8O7 + 3NaHCO3 --› 3Na+ + C6H5O73- + 3H20 + 3CO2

1. It takes 3 sodium bicarbonate molecules for each citric acid molecule in the reaction (I assume to get to to pH 7)
   
2. Molecular weight of sodium bicarbonate is 84.007 g/mol
3. Molecular weight of citric acid is 210.14 gmol
4. So I need 1.2x as much sodium bicarbonate as citric acid to get to neutral pH (3 * 84.007g / 210.14 g)

What I am not clear on is exactly how EDTA interacts with sodium bicarbonate. Will it bond to some of the free sodium? It won't dissolve until pH is about 8, and once it's all dissolved it ends up about pH 7. I need to then get from pH 7 to 4.5 with citric acid. I did this by just adding a little bit each time and testing with paper and as such I do not know the exact amount that I added.

So I started with 0.5g of EDTA, added bicarbonate to get it to dissolve, added citric acid down to about 4.5 pH. Just trying to double check my measurements.

Hope that makes sense.

 

[Donald Qualls]

Thanks! As @Donald Qualls said, it has a gray base (clear in 120). I am using it for testing because I had a ton of it I bought accidentally at one point when I meant to buy Arista Premium 400 (Tri-X) and instead bought Arista.EDU 400 (Fomapan 400).

Even more confusing, Freestyle used to have .EDU films (those were Fortepan), and .EDU Ultra; they've had only the Ultra version for some time (Forte folded a while back and Freestyle's warehouse stock of the rebranded film ran out several years ago). The two films are similar, but not the same (Forte has larger grain and even worse reciprocity departure than Foma). Generally, if you have the Forte and it's working well here, Foma probably will as well; Forte (along with Efke) was (in)famous for its soft emulsion.

 

[YoIaMoNwater]

Thanks! As @Donald Qualls said, it has a gray base (clear in 120). I am using it for testing because I had a ton of it I bought accidentally at one point when I meant to buy Arista Premium 400 (Tri-X) and instead bought Arista.EDU 400 (Fomapan 400). So, it's good for experimenting. And it turns out the emulsion is super forgiving of peroxide bleaches...

What I'm trying to calculate is the right amount of the ingredients in a more precise way. I know what I measured works, but I'd like to see if I'm adding too much of something or not quite enough of something else. I know that I don't have 100% purity, but it seems like I ought to be able to say:

• it takes roughly X amount of sodium bicarbonate (or NaOH) to get all of the EDTA dissolved
• it takes roughly Y amount of citric acid to get the pH back to 4.5

I know my measurements are in the right ball park, but it would be good to make sure this is right.

Sticking with sodium bicarbonate because the stuff I have seems clean, it's cheap and easy to get, I can calculate the sodium bicarbonate and citric acid part. (I think)

C6H8O7 + 3NaHCO3 --› 3Na+ + C6H5O73- + 3H20 + 3CO2

1. It takes 3 sodium bicarbonate molecules for each citric acid molecule in the reaction (I assume to get to to pH 7)
   
2. Molecular weight of sodium bicarbonate is 84.007 g/mol
3. Molecular weight of citric acid is 210.14 gmol
4. So I need 1.2x as much sodium bicarbonate as citric acid to get to neutral pH (3 * 84.007g / 210.14 g)

What I am not clear on is exactly how EDTA interacts with sodium bicarbonate. Will it bond to some of the free sodium? It won't dissolve until pH is about 8, and once it's all dissolved it ends up about pH 7. I need to then get from pH 7 to 4.5 with citric acid. I did this by just adding a little bit each time and testing with paper and as such I do not know the exact amount that I added.

So I started with 0.5g of EDTA, added bicarbonate to get it to dissolve, added citric acid down to about 4.5 pH. Just trying to double check my measurements.

Hope that makes sense.

Free acid EDTA can only be dissolved in high pH due to the many carboxyl groups (https://www.researchgate.net/post/Can-someone-explain-why-EDTA-needs-basic-condition-for-dissolving). You're basically doing everything right by getting it to pH 8 then adding it to something else and adjust the pH from there. It's hard to calculate the amount of materials you need to reach a certain pH because each compound has a different solubility. For example, if you're adding citric acid HC6H5O7 then it dissociates to H+ and C6H5O7-, but depending on the pH of the solution it's in, the equilibrium can be shifted. Basically it's always changing so it's hard to calculate how much mass of citric acid you add will get you to a particular pH, and the way you're doing by titration and checking with pH paper is exactly how experimentalist does it in the labs.

As for how EDTA reacts with sodium bicarbonate, I'm not exactly too sure on that. Maybe @kentanghk can provide a better answer since he seems to be in a chemistry lab?

 

[relistan]

Even more confusing, Freestyle used to have .EDU films (those were Fortepan), and .EDU Ultra; they've had only the Ultra version for some time (Forte folded a while back and Freestyle's warehouse stock of the rebranded film ran out several years ago). The two films are similar, but not the same (Forte has larger grain and even worse reciprocity departure than Foma). Generally, if you have the Forte and it's working well here, Foma probably will as well; Forte (along with Efke) was (in)famous for its soft emulsion.

Haha, yes I forgot about that. I have the .EDU Ultra (Fomapan). They did have .EDU from Forte originally. The mistake in the order was just clicking on the wrong thing. But it was right before I moved overseas to Germany, so I couldn't handle the return or anything. So here it is, years later, getting used for experiments.

Free acid EDTA can only be dissolved in high pH due to the many carboxyl groups (https://www.researchgate.net/post/Can-someone-explain-why-EDTA-needs-basic-condition-for-dissolving). You're basically doing everything right by getting it to pH 8 then adding it to something else and adjust the pH from there. It's hard to calculate the amount of materials you need to reach a certain pH because each compound has a different solubility. For example, if you're adding citric acid HC6H5O7 then it dissociates to H+ and C6H5O7-, but depending on the pH of the solution it's in, the equilibrium can be shifted. Basically it's always changing so it's hard to calculate how much mass of citric acid you add will get you to a particular pH, and the way you're doing by titration and checking with pH paper is exactly how experimentalist does it in the labs.

As for how EDTA reacts with sodium bicarbonate, I'm not exactly too sure on that. Maybe @kentanghk can provide a better answer since he seems to be in a chemistry lab?

Thanks! Yeah I had read about needing to get to pH 8 to dissolve it. Originally I had mixed up a solution of it and used that but it's annoying that way because of the extra dilution to the H2O2, since this bottle is 3% peroxide solution. So it's better to add the EDTA and then the bicarbonate. I see what you means about being complicated to calculate. I remembered titration from high school years ago so that's how I ended up doing what I'm doing. Sounds like that's not a silly way to do it. That's probably a good enough lesson on its own Thanks for the help

 

[relistan]

Well I tried a little snip of leader from a roll of Agfapan APX-100 (original) that I developed over the weekend. The bleach from yesterday was still good and cleared it in about 6 minutes at 17C. It's drying now so that I can see what emulsion damage there may be. It's a bit scratched, so findings may not be definitive.

But, I was encouraged that the bleach did not die over night. The pH 8 bleach I made died overnight as I had theorized that it would.

Also, I forgot to say this before, but in order to get the Fomapan 400 to clear in this bleach (vs the acetic acid bleach) I had to use a first developer with 1.5g/L sodium thiosulfate. I believe that this is a pretty good indicator that this bleach does not do much fixing. Certainly less than the acetic acid bleach does. And I think that will mean better Dmax. I will try to figure out if I can run a few frames for real this weekend. Will depend on diluting down the 12% peroxide that arrived last week and if the deionized water I have is clean enough.

 

[relistan]

Well folks, this bleach works very well, and solves all of the problems we've seen with other bleaches except emulsion damage with some films. I have run a roll of Fomapan 400 in it today and obtained good results. I decided to write up a Photrio resource for others to benefit from here, including the full, working formula with all amounts including the citric acid.

https://www.photrio.com/forum/resources/b-w-reversal-bleach-—-hydrogen-peroxide-edta-citric-acid.448/

Here's the roll I developed today:

I still have not tried the etidronic acid/HEDP that I got from Suvatlar in Germany. I will reserve some time to experiment further with that to see if it works better to handle emulsion damage. In the meantime I think it's worth celebrating some victory over most of the other issues we've seen.

cc @Raghu Kuvempunagar, @Donald Qualls, @YoIaMoNwater, @falotico, and most especially @kentanghk who all helped out here!

 

[Helinophoto]

Results

That looks pretty awesome, congratulation!

Just one question, what is EDTA, and where can you get this?
From some googling, I see it is used as a method to bind to metals, usually in relation to led-poisoning or something like this.

I see that, to get this to work, I would have to obtain a few things that seem far-fetched in Norway.

I checked some pool-supplier sites, but no obvious, separate buckets of declorinator (sodium thiosulfate), but I suppose I can keep looking.
I saw one person selling 25 kg of that stuff on the used market here lol:
Though Tetenal Variofix should contain roughly 20% of the stuff, could this be used ?

Sodium Bicarbonate I already have, because I dabbled with Caffenol.
Citric-acid can be bought in the store here (yey!)

I was also thinking to use D-76, stock solution, this is a solvent developer, not sure if that makes any difference what so ever, compared to HC-110.

 

[relistan]

That looks pretty awesome, congratulation!

Just one question, what is EDTA, and where can you get this?
From some googling, I see it is used as a method to bind to metals, usually in relation to led-poisoning or something like this.

I see that, to get this to work, I would have to obtain a few things that seem far-fetched in Norway.

Thanks!

It's Ethylenediaminetetraacetic acid (EDTA for short) and it is used most commonly as a chelating agent to bind iron and other minerals from tap water. It's found in a lot of cleaning products, some foods, and some photochemistry. They do use it in treatment for lead or other heavy metal poisoning.

I ordered it in Ireland from a place that sells chemicals that are mostly related to cleaning products. It's available in various forms including tetra- and di-sodium salts. The stuff I have is the free acid and it's not water soluble (hence all the bicarbonate). If you are trying to find it in Norway you might try agricultural supply or cleaning supply places. Brand names include Dissolvine Z and Versene. There are many "Dissolvine" products, so pay attention to the "Z".

These folks in France look like they will ship all over Europe: https://www.mon-droguiste.com/ethylene-diamino-tetraacetic-acide.html They are selling the EDTA tetrasodium salt. @Anon Ymous contributed some calculations for substituting that into the formula and I will post those.

Note that bicarbonate is different than the carbonate often used in Caffenol. Bicarbonate is baking soda or bread soda. I am using some Irish brand from the supermarket.

I checked some pool-supplier sites, but no obvious, separate buckets of declorinator (sodium thiosulfate), but I suppose I can keep looking.
I saw one person selling 25 kg of that stuff on the used market here lol:
Though Tetenal Variofix should contain roughly 20% of the stuff, could this be used ?

If you order stuff from that French site, they also have sodium thiosulfate: https://www.mon-droguiste.com/thiosulfate-sodium.html . Worst case try a bit of your Variofix and see what happens.

I was also thinking to use D-76, stock solution, this is a solvent developer, not sure if that makes any difference what so ever, compared to HC-110.

If you use D-76, you could add some of the sodium carbonate (not bicarbonate) that you have for caffenol and get a higher contrast developer. That might work fine. But I think you said you have paper developer and that would be my first choice.