Hi Jay, Sharing what I know: Normally the R-9 bleach recipe is potassium dichromate + sulfuric acid. Others may have more to say about using permanganate—I’ll be curious if anyone has had good success with it. I know others who’ve used citric acid + hydrogen peroxide, but it takes a long time (90 minutes), and I can’t speak to how the results compare.
The last time I needed R-9 I wasn’t able to source either the sulfuric acid or potassium dichromate (I used to buy these from Photographer’s Formulary. Potassium dichromate is also used for gum bichromate—where are people finding it these days??). You might try a university chemistry lab. I ended up buying the R-9 premixed from Antec: https://kyantec.com/tips-tricks/photographic-chemicals/ — they will make whatever quantity you need (I ordered 2.5L, I want to say it was about $80). It’s not the most cost effective, but it wasn’t exorbitant. And you don’t have to worry about mixing. Be very careful handling this chemistry either way! It’s carcinogenic amongst other things. Wear gloves and goggles, use clearing bath on anything it touches. If you haven’t seen it, this isn’t a bad resource for BW Reversal Processing: https://tishstringer.com/wordpress/wp-content/uploads/2020/01/16mmGuide_Final-1.pdf I do this process (as well as E6) at my community darkroom with good ventilation. I ran a workshop recently using this chemistry, but to be honest I’m not sure I would again—the chemistry feels a little intense for learners. I would like to fully move to a less toxic alternative even for myself. Looking forward to hearing others’ comments. j. On Wed, May 20, 2026 at 7:38 PM Jay Hudson <[email protected]> wrote: > I am trying to source B/W Reversal Bleach, but for Kodak only sells it > quantities that are far in excess of what I need. > > I also don't want to get a kit that comes for other chemicals. > > It looks like I might have to mix the bleach myself. If I recall, you can > make it with potassium bichromate or potassium permanganate, or something > like that. I have also saw a mixture described with hydrogen peroxide and > white vinegar. > > I would appreciate any information that someone might have (especially > safety information with mixing chemicals) > > --Jay > -- > Frameworks mailing list > [email protected] > https://mail.film-gallery.org/mailman/listinfo/frameworks_film-gallery.org >
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