A modified version of Kodak R9 works for me at home and in workshops. I have had success with Hydrogen Peroxide (35%) and Vinegar (5% acetic acid) – love the Braille-like bumps on Fomapan R100– but it is inconsistent (nothing against that concept). NOTE: DO NOT STORE THIS IN AIRTIGHT CONTAINER!! The plastic bottle that exploded nearly cost me my darkroom at home (know what I’m saying?)
Sodium Bisulfate (pure) can substitute for 98% pure Sulphuric Acid. (4.3g to 1ml). It is sold, for example, as a swimming pool maintenance product. In Canada at a hardware store, “Aquarius pH- (minus) Step 1 Water Treatment” is pure Sodium Bisulfate (not Bisulfite) for C$8 for 1.4 Kg. [Note the sister product, pH+ is pure sodium carbonate, that is often sourced as “washing soda”]. Potassium Dichromate (D, not B), for example from Argentix.ca (near Montréal) is C$9 for 70 grams. Recipe that works for me: 20g Sodium Bisulfate (not “fite”) 2.5g Potassium Dichromate (D, not B) Mix in water to make one litre. Use in room light “to completion”; you can’t over-do it: when the black silver metal is gone, it’s gone. (Thanks, Richard Tuohy for informing me of this and that you can work in room light after first developer/stop bath). Different stocks and varying exposure/first developer action show more or less transparency where the black silver metal was. One litre for a cost of about C$0.45 (forty-five cents). This is a “weak” version of the recipe, re-useable for a hundred feet of 16mm, probably more. Increase time/temperature if it appears not to work any more (or mix some more fresh). I take the exhausted liquid to the local hazardous waste drop. I use a dust mask when scooping from the jar and mixing. Once in liquid solution I just use gloves. There is much diving to be done on this topic in the photography forums. Sandy On Wed, May 20, 2026 at 8:26 PM jenelle stafford <[email protected]> wrote: > 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 >> > -- > Frameworks mailing list > [email protected] > https://mail.film-gallery.org/mailman/listinfo/frameworks_film-gallery.org >
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