mr.datsun: what about using dithionite as a redeveloper? Do you still get that brown tone?
I've literally started reversal processing B&W this week, and my first results were not perfect (lack of contrast on FP4+) but certainly there was something usable (accidentally overexposed the film by 1/2 stop - maybe that's it?)!
I've done a lot of reading and seem to come across a couple of conflicting ideas regarding potential brown staining caused by a KMnO4 + H2SO4 bleach. Some methods suggest that this stain can be cleared using a Na2S2O5 solution (not sure if this is what's in the Foma clearing bath you use) but some methods suggest that Na-metabisulphite will NOT work, and instead one must use potassium metabisulphite.
Now, as I mentioned, I've started playing with B&W reversal this week and I used a KMnO4 + H2SO4 bleach with a NaS2O5 clearing bath and it worked fine... perhaps the staining issue is therefore dependent on the age of solutions?
I don't know if there's anything useful in my musings, but maybe it is worth checking/changing your clearing bath and see if that eliminates the problem? BTW - my method (at this early stage) is an almost direct implementation of that in Jens Osbahr's pdf (freely available online - and linked to on here), in which Rodinal is used as the 1st & 2nd Dev. - seemingly without any significant brown-tone issues. The only change I made was that I used Ilford multigrade as the 1st and 2nd dev. and like I said, slight lack of contrast (and possibly low D-max) - but worked with no staining.
I see that Jim beat me to this post, but I will let this be here for the link and clearing bath suggestion.
This could indicate too strong bleach or rather incorrect bleach to clearing bath intensities.
What is the composition of the bleach you are using ? Duration of bleach ?
Do you have access to sodium metabisulfite (Na2S2O5) other than foma kit? (To be used as clearing bath)
Please try using R09 as both first and second developer.
if you are using Ilford bleach recommendations, reduce the strength to half (see this method http://home.snafu.de/jens.osbahr/pho...r_reversal.pdf ).
If you have access to sodium metabisulfite, use it as recommended in osbahr pdf => 1g in 260ml and clear for two minures. Increase clearing bath time if brown tone remains.
I have developed Ilford FP4+ as per the above instructions and got very good results. Will post scans after I receive them.
I always planned to switch to NaS2O5 once the Foma kit was done. So I'm going to do it now as I'll have to get used to using it anyway.
It was re-reading Osbahr that made me decide to go back to Rodinal and give that another shot.
It seems that the low contrast is the bugbear of all home reversal processes. Are you using the chemical fogging agent?
With regards the Foma bleach, I only know that it's Sulphuric acid and Potassium Permanganate and have no idea of the strengths of the individual components. When the current Foma kit run out I will be mixing my own bleach.
I have used R09 as both first and second. I switched to Dokumol to test whether the 2nd R09 was contributing to the brown tone.
I've also noticed in my last test that doubling the hypo in the 1st dev apparently served to remove the brown tone (at least with the R09/Dokumol). But the two tests images were quite different in their ratio of dark to light , so I do need to confirm that.
Look forward to seeing your scans.