B&W Reversal Bleach — Hydrogen Peroxide/EDTA/Citric Acid

[relistan]

relistan submitted a new resource:

B&W Reversal Bleach — Hydrogen Peroxide/EDTA/Citric Acid - A good peroxide bleach with no staining and good performance

A number of us worked for about a month and a half testing and developing some hydrogen peroxide-based B&W reversal bleaches. The peroxide/acetic acid bleach that started it all, linked in the first post on that thread is OK. Its advantage is that it is dead simple. It has many disadvantages. Other people have used citric acid-based peroxide bleaches for both paper reversal and film reversal...

Read more about this resource...

 

[osella]

Thanks to all those involved, I’m going to try this when I get a chance. Does the formula refer to disodium or tetrasodium EDTA?

 

[relistan]

Thanks to all those involved, I’m going to try this when I get a chance. Does the formula refer to disodium or tetrasodium EDTA?

Awesome! Would love to hear how you do. In the recipe it's the free acid, not either of the sodium salts. Either one _should_ work but you will need to adjust amounts by molecular weight.

 

[Ares_der_Ruderer]

Would this work with Fomapan R100 too would you guys reckon ?

 

[relistan]

Would this work with Fomapan R100 too would you guys reckon ?

I have some but have not yet tried it with this formula. This film has a pretty special emulsion and in addition has a silver-based anti-halation layer that seems to really activate peroxide bleach. I will snip a little section and try it in the morning and let you know.

 

[Anon Ymous]

Thanks to all those involved, I’m going to try this when I get a chance. Does the formula refer to disodium or tetrasodium EDTA?

Reduce sodium bicarbonate by 6,9g if you use the disodium salt, or by 13,8g for tetrasodium.

 

[relistan]

Reduce sodium bicarbonate by 6,9g if you use the disodium salt, or by 13,8g for tetrasodium.

Awesome, thanks! I'll add this info to the recipe. It seems like you also need to add more of the EDTA salt as well?

 

[Ares_der_Ruderer]

I have some but have not yet tried it with this formula. This film has a pretty special emulsion and in addition has a silver-based anti-halation layer that seems to really activate peroxide bleach. I will snip a little section and try it in the morning and let you know.

Cheers. If it does work, I am also contemplating using this bleach to develop R100 as a negative. I read long ago, that one could achieve this with R100 if you bleached first (to get rid of the integrated anti hallation layer), then developed using the normal B&W negative process. But so far, the only reversal bleaches I was aware of required hard to acquire dangerous chemicals, which put me off this experiment.

 

[Anon Ymous]

Awesome, thanks! I'll add this info to the recipe. It seems like you also need to add more of the EDTA salt as well?

Ah, yes, but keep in mind that these may come in hydrated forms. If anhydrous, you need 13,8g of the disodium salt, or 15,6 of the tetrasodium.

 

[Raghu Kuvempunagar]

Having easy access to both dichromate and permanganate, I'll probably never use a peroxide bleach, but it's nice to have a formula that works reasonably well for a few films and serves as the starting point for rest of the films. You fully deserve credit for doing the hardwork and arriving at such a formula.

Now I hope someone tries the formula with Adox Scala films and gets good results. As these films are engineered for reversal processing, ability to DIY processing and get great results without needing to use the expensive and out of stock reversal kit might spur interest in B&W slides.

 

[relistan]

Having easy access to both dichromate and permanganate, I'll probably never use a peroxide bleach, but it's nice to have a formula that works reasonably well for a few films and serves as the starting point for rest of the films. You fully deserve credit for doing the hardwork and arriving at such a formula.

Now I hope someone tries the formula with Adox Scala films and gets good results. As these films are engineered for reversal processing, ability to DIY processing and get great results without needing to use the expensive and out of stock reversal kit might spur interest in B&W slides.

Thanks, Raghu! Also appreciate your many contributions on that thread. I still intend to keep iterating on it to see if I can get something that works better with Scala 160/Silvermax 100. I don't have any Scala 50, but since it's a totally different film it might work better. I think the path forward for Scala 160/Silvermax is to figure out how to pre-soften the emulsion before bleaching. I am not convinced so far that anything else will solve the problem.

 

[relistan]

Ah, yes, but keep in mind that these may come in hydrated forms. If anhydrous, you need 13,8g of the disodium salt, or 15,6 of the tetrasodium.

Thanks, I'll get this updated today to add these.

 

[relistan]

Cheers. If it does work, I am also contemplating using this bleach to develop R100 as a negative. I read long ago, that one could achieve this with R100 if you bleached first (to get rid of the integrated anti hallation layer), then developed using the normal B&W negative process. But so far, the only reversal bleaches I was aware of required hard to acquire dangerous chemicals, which put me off this experiment.

Bad news, I'm afraid. While it doesn't destroy the film like the acetic acid-based bleach did, it still causes quite noticeable emulsion damage. I would suggest not using it on this film.

 

[relistan]

Thanks to all those involved, I’m going to try this when I get a chance. Does the formula refer to disodium or tetrasodium EDTA?

I have updated the post with the calculations for anhydrous versions of these two salts, thanks to @Anon Ymous above.

 

[Huugo]

Hi i'm new in this forum. I live in Spain and getting high concentrated peroxide it's impossible to me so i was very excited to read this post. The thing is i want to use this process for paper direct positives (as Joe Van Cleave and Ethan Moses) I took some test a few weeks ago and i got some result, not usable but i got some conclusions. As Ethan recommended i use citric acid and bleach in separated steps (and going back and forth when bleach got exhausted) to get it to...refresh itself? I also overexposed the shots by 2 and 3 steps.
First conclusions:
It takes to long, like 5-6 mins to start to bleach high lights. In addition the shots were quite underexposed even though i got the negative to be almost black with little detail. Also and that's totally my fault, the photos were stained too as i ordered sodium sulphate instead of sulfite (idiot). I didn't used sulphate i just skipped that step.

Has anyone tryied this process for paper reversal? Any recommendations to boost the power of the bleach ?

Thanks!!

 

[relistan]

Hi i'm new in this forum. I live in Spain and getting high concentrated peroxide it's impossible to me so i was very excited to read this post. The thing is i want to use this process for paper direct positives (as Joe Van Cleave and Ethan Moses) I took some test a few weeks ago and i got some result, not usable but i got some conclusions. As Ethan recommended i use citric acid and bleach in separated steps (and going back and forth when bleach got exhausted) to get it to...refresh itself? I also overexposed the shots by 2 and 3 steps.
First conclusions:
It takes to long, like 5-6 mins to start to bleach high lights. In addition the shots were quite underexposed even though i got the negative to be almost black with little detail. Also and that's totally my fault, the photos were stained too as i ordered sodium sulphate instead of sulfite (idiot). I didn't used sulphate i just skipped that step.

Has anyone tryied this process for paper reversal? Any recommendations to boost the power of the bleach ?

Thanks!!

Very late reply, but use the bleach from this thread, and do not separate it like the one Joe and Ethan used. You need to use it in a single bath. This should be much faster. Without the citric acid in the bleach the pH is all wrong and the result will be slow or no bleaching. If you follow this link https://imager.ie/a-better-peroxide-black-and-white-reversal-bleach/ and scroll all the way down, a reply there shows the paper reversal results that someone achieved.

 

[Ausar]

I wonder why do we need NaHCO3 here? we need it's Na+, or we need to adjust ph value?

 

[koraks]

we need it's Na+, or we need to adjust ph value?

Clearly the latter.
There's very little (probably nothing) in the realm of photography we specifically want sodium ions for.

 

[Ausar]

Clearly the latter.
There's very little (probably nothing) in the realm of photography we specifically want sodium ions for.

which ph value is best? and, I found in some old recipe, people use 9% H2O2 and acetic acid，can Citric Acid replaced by acetic acid?

 

[relistan]

which ph value is best? and, I found in some old recipe, people use 9% H2O2 and acetic acid，can Citric Acid replaced by acetic acid?

In the write-up I actually gave the target pH. https://imager.ie/a-better-peroxide-black-and-white-reversal-bleach/ . You can try any experiments you like, but the whole point of using EDTA and citric acid in this bleach was to avoid the runaway reaction that acetic acid/vinegar triggers, and to avoid 9% peroxide. Read the blog post I linked and the previous one (linked from there).

 

[Nicholas Lindan]

Has anyone tried a hardening bath before bleaching to minimize emulsion damage in the bleach?

Unfortunately, the two common hardeners are chrome alum (back to square one with the goal of not using chromium) and formaldehyde (somewhat nasty, but it does biodegrade completely).

 

[koraks]

chrome alum (back to square one with the goal of not using chromium)

There's a very big difference in terms of toxicity and overall harmfulness between chromium VI (like in dichromate) and chromium III (like in chrome alum). Sure, it's still a heavy metal ion, but it's also one that naturally occurs in trace amounts in the human body, for instance.

 

[relistan]

Has anyone tried a hardening bath before bleaching to minimize emulsion damage in the bleach?

Unfortunately, the two common hardeners are chrome alum (back to square one with the goal of not using chromium) and formaldehyde (somewhat nasty, but it does biodegrade completely).

From testing, it appears that the more hardened films may actually perform worse with regard to emulsion damage. Fomapan 400, for example, performs well and is soft. That said, I did not, nor did anyone else to my knowledge, explicitly try a hardener. If you have time and inclination, I'd love to see the result.

 

[artyfarty]

Hello!
I tried to mix this bleach with what i can obtain in Turkiye (actually it's surprisingly easy to buy even dangerous chemistry on a marketplace here), however i failed twice - bleach didn't work like at all.
I tried it with Ilford RC multigrade paper (the only type of paper i can easily buy) and also used a piece of developed film to control.

With proposed mix it didn't work at all, 7 minutes, 1 hour, continius agitation - nothing.
Today I got another citric acid which i was more sure of and tried again. This time i just used test pieces of paper and film to test it after mixing and was slowly adding ~1g of citric acid per minute, but even after 10g or so it barely started to do something. No clouding either.

I wonder if i mistranslated or misunderstood something.
I used:
* Hydrogen Peroxide 3% (lab grade) 300ml
*15.7g EDTA-4Na powder. anhydrous/not or purity not specified, but was packaged as chemistry supply
* 5.7g sodium bicarbonate - generic box of whatever, may be kitchen soda or something. There was a lot of bubbling on this stage as advertised.
* Citric Acid 99% 11g (tried adding more). It was in fairly small crystalline granules, not a powder


I'll appreciate any advice.
p.s. i only have ph tests that goes down to 6.8 and all i can say is that ph of my mix was less than 6.8. I've ordered some wider range test strips.

 

[relistan]

Hello!
I tried to mix this bleach with what i can obtain in Turkiye (actually it's surprisingly easy to buy even dangerous chemistry on a marketplace here), however i failed twice - bleach didn't work like at all.
I tried it with Ilford RC multigrade paper (the only type of paper i can easily buy) and also used a piece of developed film to control.

With proposed mix it didn't work at all, 7 minutes, 1 hour, continius agitation - nothing.
Today I got another citric acid which i was more sure of and tried again. This time i just used test pieces of paper and film to test it after mixing and was slowly adding ~1g of citric acid per minute, but even after 10g or so it barely started to do something. No clouding either.

I wonder if i mistranslated or misunderstood something.
I used:
* Hydrogen Peroxide 3% (lab grade) 300ml
*15.7g EDTA-4Na powder. anhydrous/not or purity not specified, but was packaged as chemistry supply
* 5.7g sodium bicarbonate - generic box of whatever, may be kitchen soda or something. There was a lot of bubbling on this stage as advertised.
* Citric Acid 99% 11g (tried adding more). It was in fairly small crystalline granules, not a powder


I'll appreciate any advice.
p.s. i only have ph tests that goes down to 6.8 and all i can say is that ph of my mix was less than 6.8. I've ordered some wider range test strips.

I have pure EDTA here and that's what Kentanghk and I did all the testing with. The amounts for the sodium salts were contributed here by @Anon Ymous . According to this link: https://longkey.com/blog/edta-2na-vs-edta-4na-key-differences/ it looks like the 4na salt has a lot higher pH and that probably should require a fair bit more citric acid to offset it. If it turns out you need a lot more, I'd be happy to update the blog post for this case! I think you're going to need to be able to measure the pH yourself (as you said). If the strips don't work out, the fairly cheap pH meters from Amazon have worked fine for me. If you overshoot the pH and get it a lot too low, you get little to no bleaching as well. It's important to be about right. Hopefully you can measure it with the new strips. Please let us know what you end up with. Good luck