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  1. #11
    mrred's Avatar
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    If you tried ACROS 100 you would have gotten a strip of black. The properties of the film have everything to do with it. I guess how fast or slow a film fixes is an indecator for how much hypo to use.

    I always do a quick inspection after the bleach. It's nice to know early when I have screwed up.

    I tend to do strips initally, exposing -5 to +5 in 1 stop increments - with a grey card and cards in the shot stateing what exposure it is. I start off with no hypo and go from there. It's a pretty fast way to ball park.

  2. #12
    Mike Wilde's Avatar
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    I know I am late to this thread, but every first developer formula I have seen used thiocyanate, not thiosulfate.

    The thiocyanate makes sure everything that iis on the verge of being developed gets developed is the way I understand it.

    That means that the clear areas of the final product transparency are as clear as they can be, rather than being dim with residual fog.

    I am most willing to be corrected on this, however. I am working on memory, and not my reversal processing notes to make these comments.
    my real name, imagine that.

  3. #13
    Rudeofus's Avatar
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    Mike, I linked to one recipe for B&W reversal with thiosulfate and one with thiocyanate. I have no idea which one is better or whether there is a difference at all.
    Trying to be the best of whatever I am, even if what I am is no good.

  4. #14
    holmburgers's Avatar
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    According to E.J. Wall and also Grant Haist, potassium thiocyanate is the preferred solvent at 0.2% according to Wall/Jordan and at 0.5% according to Haist. Above 5g/L and density goes down, below 5g/L and ISO drops and you get longer development times.

    Contrary to popular formulas, hypo is not considered to be very good, resulting in lost shadow density.

    Never tried it myself, but that's what "the big dogs" say. Here's a bit more on this post.

    Agreed that Ilford's recommendation is way too high.

  5. #15
    hrst's Avatar
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    Hypo seems to be VERY popular in formulas published on the internet. Maybe because Ilford recommends it. Or because it's more readily available; many already have it for fixer or farmer's reducer.

    I used hypo in reversal RA-4 first developer with good results at low levels. I don't remember if I tested thiocyanate or not, at least I planned to! I used thiocyanate on experimental Ilfochrome developer. It seemed to brighten shadows more than highlights. For digitally oriented people, I would say just like gamma correction tool.

    Both can be used for the same purpose, but probably with a little bit different kind of results. It's HEAVILY dependent on film but also heavily a matter of taste. The only way to know is to test.

    For example, do test strips with no hypo - 0.25 g/l - 0.5 g/l - 1 g/l - 2 g/l - 4 g/l and same with KSCN. Bracket exposures for every test strip widely enough, because the "optimum" exposure may also vary depending on the formula.

    Anyhow, it's easiest to start with the basic formula with no halide solvent at all and then introduce it to see the effect.

    And, tinkering with the formula is not by any means limited to just halide solvent. Maybe to keep it simple, I would take the development time as a parameter, too.

    Then there is SLIMT......

    You could dedicate your whole life to just one reversal process if you wanted to. Or you can just pick a formula to get some results you will probably like.

  6. #16
    spatz's Avatar
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    Quote Originally Posted by NDP_2010 View Post
    very good info here thanks everyone.

    oxley, where do you obtain the hypo in australia? Also can you give more details on the dichromate bleach, is it still used with sulfuric acid? what concentrations (and also where do you purchase it?)

    thanks.
    All the ingredients can be bought from vanbar in sydney (the dont stock it - it comes from vanbar in melbourne and takes around a week to get to sydney) except for the sulfuric acid. i replaced it with sodium bisulfate which you can buy by the kilo from pool stores which is sold as a pH reducer. for the 1 litre bleach i use around 60g of sodium bisulfate. i havent tried it but you can buy a product called mo-flo (blackwoods stock it as a drain cleaner) which i believe is around 40% sulfuric acid which you can water down to the right concentration.

  7. #17

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    Typically thiosulfate is used at twice the concentration recommended for thiocynate. They are used to cleanup the hightlights when making BW slides. The usual concentration is 2 to 4 grams of thiosulfate per liter of first developer.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  8. #18
    NDP_2010's Avatar
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    would it be possible to use a small amount of fixer (i have rapid fixer) instead of the thiosulfate?
    pentax 6x7,canon eos 300, crown graphic 4x5

  9. #19
    Oxleyroad's Avatar
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    Quote Originally Posted by NDP_2010 View Post
    very good info here thanks everyone.

    oxley, where do you obtain the hypo in australia? Also can you give more details on the dichromate bleach, is it still used with sulfuric acid? what concentrations (and also where do you purchase it?)

    thanks.
    I buy from Vanbar as spatz said was possible in earlier post. The sulphuric acid I was given 4 litres of conc about 10 years ago from an old roofing plumber and it has kept me and others going for a while.

    The Bleach I use is Kodak Bleach R9; and the soup as follows
    Water - 1litre
    Potassium dichromate - 9.5g
    Sulfuric acid (concentrate ~98%+) 12ml
    Adding the acid real carefully and gradual to the solution.
    Cheers - Andy C
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    16mm Cine, 35mm, 120, 5x4 & 7x5.

  10. #20

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    Quote Originally Posted by NDP_2010 View Post
    would it be possible to use a small amount of fixer (i have rapid fixer) instead of the thiosulfate?
    NO, fixer contains other chemicals other than thiosulfate which could have undesirable effects on the developer. Even plain ammonium thiosulfate cannot be used. You have to use sodium thiosulfate or sodium/potassium thiocyanate.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

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