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  1. #1

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    Replace PPD by CD-3

    My local supplier only has CD-3 not PPD.

    PPD MW=108.14
    www.chemblink.com/products/106-50-3.htm
    CD-3 MW=836.97
    www.chemblink.com/products/25646-71-3.htm

    Should I use 836.97 parts CD-3 to replace 108.14 parts PPD by weight?
    It's for a B/W film developer.
    Thanks.

  2. #2

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    No, you need to divide the MW of the CD-3 by 2 in your calculation. What developer are you trying to modify? There are other things to consider besides MW. There are two base units considered in their MW. Usually the MW of such things as CD-3 are given as the sesquisulfate.
    Last edited by Gerald C Koch; 10-14-2010 at 10:35 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

  3. #3
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    CD-3 is very weak compared to PPD in many developer formulas.

    PE

  4. #4

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    Thanks,

    I would like to make Sease no1 superfine grain developer equivalent.

    paraphenylenediamine (base).............10g
    Sodium Sulfite (anh).........................90g
    Water to..........................................1L

    I don't think Photoformulary.com can ship PPD outside the US any more so in many countries it will now be unobtainable.

  5. #5
    Ian Grant's Avatar
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    CD-2 is more usually used as a replacement for PPD, that's what Geoffrey Crawley recommended in the 1960's as a substitute.

    Ian

  6. #6
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    Yes, I agree with Ian. Good choice and less toxic and less subject to aerial oxidation. However, as CD-2 comes as an acid salt, you will have to adjust the pH to the correct value. In this case I have no idea what that would mean. Maybe the Crawley formula would suggest something.

    PE

  7. #7

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    What if you tried to replace it with Paracetamol instead its sold at the local pharmacy as Tylene or Paracet I think.

    I've been eyeing Sease #1 myself, a treue superfine grain develolper is good for modern-day film in oldtime cameras, to get ISO down from todays 100 - 200 ISI to yeesterdays 25 - 50 ISO, and the superfine grain is free!

    Erik

  8. #8

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    CD-2 MW=214.7
    www.chemblink.com/products/2051-79-8.htm
    It appears Photoformulary may ship it.

    Should I use 214.7 parts CD-2 to replace 108.1 parts PPD by weight?

  9. #9
    Ian Grant's Avatar
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    Activity is not in step with Molecular weight, also Sease 1 is the worst of the series, the commercial out come was ND-3 which is a variant of Sease 3.

    Ian

  10. #10

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    Quote Originally Posted by Alan Johnson View Post
    Thanks,

    I would like to make Sease no1 superfine grain developer equivalent.

    paraphenylenediamine (base).............10g
    Sodium Sulfite (anh).........................90g
    Water to..........................................1L

    I don't think Photoformulary.com can ship PPD outside the US any more so in many countries it will now be unobtainable.
    Whatabout a replacement of PPD with Vitamin C?
    To turn Vit C into Ascorbate I'd offer the following :

    water 100ml
    5 gram Soda
    15gram ascorbic acid

    Add 700ml water
    90gram sodium sulphate
    top up to one litre

    The first step will see to it that the soda reacts and turns the Vit-C into ascorbic
    the rest mimics Sease.

    Just a suggestion, ascorbate is a known finegrain developer that dissolves silver, just as it should, but maybe too active?

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