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Thread: B&W Reversal trouble-shooting (bleaching in particular)

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  1. #1

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    B&W Reversal trouble-shooting (bleaching in particular)

    I quick trouble-shooting question for those experienced with B&W reversal processing (perhaps a bit niche but never mind - this is for making analogue positives to make Anthotypes with).
    I had good initial success with a test roll of 135 and two sheets of 10x8 FP4+, using the DIY instructions posted here and on Photrio - using two strengths of Ilford Multigrade, and a H2O2/EDTA/Bicarb/Citric Acid bleach followed by a clearing bath.

    I then attempted to process two further sheets of 10x8 last night - again, using Stearman SP810 daylight trays. Sadly the bleach stage appears not to have worked, and I ended up with two to all intents and purposes black sheets of film. The first developer produced good looking negatives, but the bleach failed to bleach out the highlights to any discernible extent, meaning that the clearing bath didn't do much if anything. Rexposure and second development only affected the shadows, thus producing a black sheet of film.

    So the culprit was the bleach step: I'm still not exactly sure what happened, but I think for these two sheets (green leaves and bright/white flowers on a pure black background) the bleaching stage wasn't long enough. For certain negs it may be that the bleaching needs rather longer. Additionally, the bleaching time I used (9 minutes) is for continuous rotation in a Jobo tank, perhaps usually by far the easiest way of doing this, though not for sheet film. So for continuous agitation in a tray I suppose that an extra minute or so would be usual and I should try that. I've also rechecked my chemistry mix and it's fine (and has been confirmed to work already, on my first three attempts). So probably not bleached for long enough - I should inspect and persist.

    I'm still not certain why an image with fewer highlights in it would take longer to bleach, but perhaps the answer is counterintuitive? Perhaps it's the case that the bleach needed to have a particularly localised effect, in the centre of the compositions?

    Anyone any further ideas esp on the latter aspect? Thanks in advance.
    http://www.davidfearnphotography.co.uk
    see too my 5x4 and 8x10 flickr albums

  2. #2

    Re: B&W Reversal trouble-shooting (bleaching in particular)

    You may want to try doing bleach-by-inspection in a tray under red safe light or subdued light till all the silver in the negative image is bleached out. Note that the bleach formula based on peroxide you have used is not as extensively tested or widely used in reversal processing like dichromate and permanganate bleach. I guess dichromate is not an option these days but if permanganate is available to you, I suggest switching to permanganate bleach.

  3. #3
    Ironage's Avatar
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    Re: B&W Reversal trouble-shooting (bleaching in particular)

    Yes, that bleach is unfamiliar to me also. Maybe it was depleted from exhaustion or age. With the dichromate bleach I’ve used this has never been a problem. Other possible problems could be the first developer of course.
    ...Dilettante! Who you calling a Dilettante?

  4. #4
    Ironage's Avatar
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    Re: B&W Reversal trouble-shooting (bleaching in particular)

    Yes, that bleach is unfamiliar to me also. Maybe it was depleted from exhaustion or age. With the dichromate bleach I’ve used this has never been a problem. Other possible problems could be the first developer of course.
    ...Dilettante! Who you calling a Dilettante?

  5. #5
    http://www.spiritsofsilver.com tgtaylor's Avatar
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    Re: B&W Reversal trouble-shooting (bleaching in particular)

    I had good results using DW-1 bleach (David Woods, aka Dr5) and DW-2 clearing bath as set out in 3d edition of Anchell's Darkroon Cookbook. See https://www.largeformatphotography.i...sing-with-D-11 for the details.

    Thomas

  6. #6

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    Re: B&W Reversal trouble-shooting (bleaching in particular)

    Thanks all. My assumption is that I didn't go for long enough with the particular neg, and that doing it by inspection would be very sensible: I can do that very easily with the SP810 trays. I'm not eager to switch bleach chemistry, and this exact mix worked absolutely perfectly for the first three attempts with a previous batch. I'll retry. Not a big deal because a subsidiary process for anthotypes, which aren't exactly run-of-the mill fare.
    http://www.davidfearnphotography.co.uk
    see too my 5x4 and 8x10 flickr albums

  7. #7

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    Re: B&W Reversal trouble-shooting (bleaching in particular)

    The procedure I used to follow when reversal developing B&W was based on the famous and now 'forgotten' AGFA DIA-DIRECT procédé, giving very good results with ILFORD DELTA 100.
    I include the scanned data sheets from 1977 as I received these from AGFA-Gevaert N.V. Mortsel, forgive me for not translating it, it's written in Flemish my native language...

    Click image for larger version. 

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  8. #8

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    Re: B&W Reversal trouble-shooting (bleaching in particular)

    I started out doing reversals with H2O2/citric acid, experimenting with different ratios/alternating baths (even tried 18% H2O2!), etc. and although some results were OK, always had problems with totally bleaching the negative. I did find fresh H2O2 worked better than used, and higher percentages worked better, and that overexposing the negative around one stop gave better results, but the dull and sometimes pitted looking emulsion, especially on paper negatives bugged me, as well as the variability in results. It would be nice if there was a way to test the strength of the H2O2 before starting, or the overall effectiveness before committing to a large negative. I suppose you can chop up your black negatives and use them as test strips when you mix up your bleach. Just pop one in the bleach and see if it clears the black negative in 9 minutes.

    I took the plunge and ordered some potassium dichromate from an art supply store (used as pigment), and got a liter of 35% sulfuric acid from a car parts store and mixed up a 1.2% sulfuric acid with 1% dichromate solution and haven't really looked back. It works so well, completely bleaching, and it works fast, under a minute for film and around 30 seconds for paper. Plus, I've stored this solution for 2 months and it still works fine--250ml bleaches at least 8-10 4x5 negs. Yes, it's pretty toxic, but with the proper PPE I think the risk is manageable.

  9. #9

    Re: B&W Reversal trouble-shooting (bleaching in particular)

    Quote Originally Posted by jimskelton View Post

    I took the plunge and ordered some potassium dichromate from an art supply store (used as pigment), and got a liter of 35% sulfuric acid from a car parts store and mixed up a 1.2% sulfuric acid with 1% dichromate solution and haven't really looked back. It works so well, completely bleaching, and it works fast, under a minute for film and around 30 seconds for paper. Plus, I've stored this solution for 2 months and it still works fine--250ml bleaches at least 8-10 4x5 negs. Yes, it's pretty toxic, but with the proper PPE I think the risk is manageable.
    Dichromate bleach is indeed the best bleach for reversal processing. Toxic it is but safe disposal of used bleach is a practical challenge. I believe that's he reason why many want to take the path of peroxide-citric bleach.

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