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  1. #41
    Rudeofus's Avatar
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    Your film is so spectacularly insensitive, that the UV attenuation from your red filter doesn't change much. If you can get the process sufficiently reproducible, you should see a slight difference in film sensitivity with and without red filter.

    BTW: you may be able to get better results if you add KBr to your CuCl2 bleach. We all know from Microdol that Chloride is a weak Silver solvent, whereas if you add Bromide this effect should be mostly suppressed.
    Trying to be the best of whatever I am, even if what I am is no good.

  2. #42
    yurisrey's Avatar
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    I see. Is there a particular name for this effect? (I'm quite cat-like when it comes to curiosity)
    extinction meters tend to be more accurate if you substitute your morning oj for carrot juice.

  3. #43

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    Quote Originally Posted by Herzeleid View Post
    copper chloride bleaches the fully developed silver and then re-halogenates it. Re-halogening is the key, for example potassium ferricyanide bleach does not re-halogenate the silver. Correct me if I am wrong.
    While the bleach may convert the silver to silver chloride, modern films are mostly silver bromide with some silver iodide. In addition all the sensitizing dyes are washed out. This thread does not describe something wondrous but rather a pointless experiment. Sorry.
    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

  4. #44
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    If you want more speed, use a Ferricyanide / bromide rehal bleach. There are many formulas here and there on APUG and the internet. Use the same exact process, but use the ferri rehal bleach instead of Copper Chloride. This change will give you AgBr which is sensitive to visible light and will give more speed.

    If you wish, after you finish the entire rehal process, you can bathe the film in a 10% solution of Erythrosine and then wash until the water changes from red to clear. Now, if you are lucky, you have an orthchromatic film to use and it will have either less or more speed. It will be less if too much dye is used and more if you used just the right amount.

    PE

  5. #45
    Rudeofus's Avatar
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    Quote Originally Posted by yurisrey View Post
    I see. Is there a particular name for this effect? (I'm quite cat-like when it comes to curiosity)
    The effect is simple: while Silver Chloride (AgCl) is quite insoluble, Silver also forms higher order complexes with the Chloride ion which are quite soluble. That's the reason why NaCl in Microdol-X increases its solvent property, and why a saturated NaCl solution can even work as make shift fixer for Silver Chloride paper. You read correctly, NaCl won't fix AgBr or AgI, because AgBr is by orders of magnitude less soluble, so you can't fix film that way, at least not to archival standards.

    Conclusion: CuCl2 might work well if diluted, but once you make it more concentrated, it will eat away some of the Silver Chloride just formed. By adding KBr you form mostly AgBr, not AgCl, and that won't be dissolved in quantity by Chloride.
    Trying to be the best of whatever I am, even if what I am is no good.

  6. #46
    yurisrey's Avatar
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    Thanks Rudeofus and PE, I will try the ferricyanide/bromide bleach.
    extinction meters tend to be more accurate if you substitute your morning oj for carrot juice.

  7. #47

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    It has been my experience that copper bleaches cause softening of the emulsion.
    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. #48
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    Quote Originally Posted by Gerald C Koch View Post
    It has been my experience that copper bleaches cause softening of the emulsion.
    I agree, they do very much so. Not an ideal bleach at all. I recall the mordançage technique uses copper chloride, while it bleaches allowing for re-exposure, it also does one heck of a job on the emulsion.
    extinction meters tend to be more accurate if you substitute your morning oj for carrot juice.

  9. #49
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    That is why, when re-exposure is desired, we use a Ferricyanide / Bromide bleach.

    PE

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