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  1. #11
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    thanks
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  2. #12
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    Had a look for recipe for dichromate bleach,

    what concentrations are people using (2g/L?) or more concentrated.


    Thanks.
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  3. #13
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    Also, is thew sulfuric/dichromate bleach one shot or can it be reused multiple times?
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    anyone? :P
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    You can use 5g/L of potassium dichromate or 10g/L if you want a stronger bleach. It's reusable a few times, but the amount of oxydant Cr2O7(2-) isn't unlimited since it decreases each time you bleach. Add about 10mL of pure H2SO4.

  6. #16
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    Quote Originally Posted by Tofek View Post
    You can use 5g/L of potassium dichromate or 10g/L if you want a stronger bleach. It's reusable a few times, but the amount of oxydant Cr2O7(2-) isn't unlimited since it decreases each time you bleach. Add about 10mL of pure H2SO4.
    thanks
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  7. #17
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    Sorry multiple times. I never bothered being accurate in measuring dichromate bleach, I just inspected until the bleaching was done, if it was too slow for my liking I increased the strength, you need very little sulphuric acid in my experience.

    I've done some good Tri-X 1600 and 3200 slides with HC-110 as first dev using Thiocyanate.

  8. #18

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    When the slides are too dense then either the film requires a lesser EI or the time in the first developer needs to be increased. If the slides are too thin then the film requires a greater EI or the time in the first defveloper needs to be shorter. Film for reversal processing is usually not shot at box speed. Remember this is reversal processing and things work sort of backwards. The exact EI varies from film to film. If you are not following a recommended procedure for a specific film then you will have to bracket at first to determine what EI is best.

    A 1 min exposure to a 250W photoflood lamp should be sufficient for re-exporure. When using SS reels the film can be left on the reel. Just hold it approximately 2 feet from the light and move the reel so the light can reach all portions of the film. A re-exposure is not needed if you use a fogging developer as given below.

    The second developer or a fogging developer goes to completion and so over development is normally not a problem. A simple re-useable bath containing 100 g of sodium carbonate and 2 g of thiourea per liter can be used instead of a conventional developer. This bath can be saved and reused several times. A commercial sulfur based toner can also be used. Both baths yield pleasing sepia colored slides. The film should not be fixed again after either of these baths but should be washed thoroughly. The T-Max films do not give good results with with thiourea or sulfide developers.
    Last edited by Gerald C Koch; 02-16-2013 at 12:46 AM. Click to view previous post history.
    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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