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  1. #11

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    mr.datsun: what about using dithionite as a redeveloper? Do you still get that brown tone?

  2. #12

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    Quote Originally Posted by Alessandro Serrao View Post
    mr.datsun: what about using dithionite as a redeveloper? Do you still get that brown tone?
    Alex. I haven't used the dithionite, at all yet. I was told by Tofek that it gave brown tone reversals at which point I put it the bottom of my To Try Next list. But I should try it. Did you it?
    Last edited by mr.datsun; 05-22-2013 at 04:28 AM. Click to view previous post history.

  3. #13
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    Quote Originally Posted by mr.datsun View Post
    Rudeofus. What would it look like, what should I look for?
    There are methods for getting rid of MnO2 stain, while Ag2S is almost impossible to remove. Tiny Silver crystals can be bleached away with C41/E6 bleach (which won't touch Ag2S). This would give you some indication what kind of stain you got. Needless to state that you only need to check for MnO2 right after the bleach step.
    Trying to be the best of whatever I am, even if what I am is no good.

  4. #14
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    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.
    Last edited by Jim Taylor; 05-22-2013 at 06:58 AM. Click to view previous post history. Reason: correct bad spelling!!!
    Cheers,

    Jim.

  5. #15

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    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.
    Last edited by davedm; 05-22-2013 at 07:34 AM. Click to view previous post history. Reason: Jim's post above (lot of common points)

  6. #16

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    Quote Originally Posted by jimbop View Post
    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.
    JIm, thanks for the ideas. And for the first time, I realised that the Foma clearing bath does have the contents printed on it. It's Sodium Pyrosulphide which I've never heard being used anywhere so far.

    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?

  7. #17

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    Quote Originally Posted by davedm View Post
    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.
    Yes, I'm trying sodium metabisulfite next time.

    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.

  8. #18

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    Quote Originally Posted by Rudeofus View Post
    There are methods for getting rid of MnO2 stain, while Ag2S is almost impossible to remove. Tiny Silver crystals can be bleached away with C41/E6 bleach (which won't touch Ag2S). This would give you some indication what kind of stain you got. Needless to state that you only need to check for MnO2 right after the bleach step.
    Rudeofus. Sorry to be dim but I don't know how to check for MnO2 stain after the bleach stage. After the bleach and clearing stage the remaining positive image is always a milky light yellow-green until it has been developed. Or is that what you mean? There are no images that capture this stage in the process to refer to, that i have seen. But I found this one from when I was using a makeshift reel and taken during re-exposure:

    Click image for larger version. 

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  9. #19

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    To be clear, I do not think I'd describe my warm brown positives from R09 as stained. I would merely say that the silver image has a warm brown tone. In that sense I do not think that it qualifies as what Osbahr calls a stain – due to incorrect clearing.

  10. #20
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    Quote Originally Posted by mr.datsun View Post
    Rudeofus. Sorry to be dim but I don't know how to check for MnO2 stain after the bleach stage. After the bleach and clearing stage the remaining positive image is always a milky light yellow-green until it has been developed. Or is that what you mean? There are no images that capture this stage in the process to refer to, that i have seen. But I found this one from when I was using a makeshift reel and taken during re-exposure:
    Since you already use a clearing bath after bleaching, I would say that MnO2 is the least likely source of your problems, and I would only look into that once you have excluded all other options. If you are not sure about your clearing bath, there is a thread here on APUG where a "rinse with dilute sodium metabisulfite (a 3% solution does the trick)" is suggested. Key seems to be Sulfite ion in acidic environment.

    Neither Ag2S, nor tiny Silver crystals will be affected by fixing, so I suggest you fix your milky test clips and check whether brown stain is visible and then check for Ag2S vs. tiny Silver Crystals. Tiny Silver crystals can be bleached away with C41/E6 bleach, while Silver Sulfide will be unaffected.
    Trying to be the best of whatever I am, even if what I am is no good.

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