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...
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?
Would this work with Fomapan R100 too would you guys reckon ?
Reduce sodium bicarbonate by 6,9g if you use the disodium salt, or by 13,8g for tetrasodium.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, thanks! I'll add this info to the recipe. It seems like you also need to add more of the EDTA salt as well?Reduce sodium bicarbonate by 6,9g if you use the disodium salt, or by 13,8g for tetrasodium.
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.
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.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?
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, I'll get this updated today to add these.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.
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.
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?
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!!
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.
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?
chrome alum (back to square one with the goal of not using chromium)
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.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).
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