Ilfotec DD-X formula?

Discussion in 'B&W: Film, Paper, Chemistry' started by Relayer, Mar 24, 2013.

  1. Relayer

    Relayer Member

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    Hello

    I found Ilford patent US5210010 with PQ formula very similar to MSDS DD-X. Also this formula have same dilution and pH as DD-X. What do you think about this?

    Potassium Sulphite 65% 548ml
    Water 380ml
    Glycol 45ml
    Hydroquinone 44g
    Phenidone 1.2g
    Borax 23.5g
    DAPTA 4.8g

    dilute 1+4, pH=8.5
     
  2. Rudeofus

    Rudeofus Subscriber

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    If you look at the MSDS, Ilford seems to use DTPA instead of DAPTA in their product. Which is good because DTPA is much easier to get and cheaper ...
     
  3. Gerald C Koch

    Gerald C Koch Member

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    There is no guarantee that this formula is anything like DD-X. Patents often contain such formulas as proof of a particular concept. Companies may try various methods of obfuscation and may even leave out important ingredients.
     
  4. michael_r

    michael_r Subscriber

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    My understanding is DDX is buffered (Borax-Boric acid).
     
  5. albada

    albada Member

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    Due to an obscure fact of chemistry, it turns out that the formula posted by Relayer is buffered, because Borax itself is buffered. When mixed into water, Borax forms the equivalent of Boric acid, thus becoming its own buffer. So Borax is self-buffering. That's why Borax is often used to calibrate pH-meters. Now, whether that formula is close to DD-X is anyone's guess.

    EDIT 1: Rudeofus prefers DTPA. Interestingly, the patent says "The preferred sequestering agent is [...] DTPA." So why didn't they use it in their sample formula?

    EDIT 2: Looking into this some more, I see that the MSDS for DD-X specifies (1) Boric acid (Michael R mentioned this), (2) Dimezone S instead of Phenidone, and (3) DTPA instead of DAPTA. So I'd say the patent was for an early formula which the engineers improved later. Based on quantity-ranges in the MSDS, I'd say this is similar to DD-X. Given this patent-formula and the MSDS, it wouldn't be hard to reverse engineer the present formula. Anyone want to try it?

    Mark Overton
     
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  6. Relayer

    Relayer Member

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    Sequestering agent isn't so important part of formula from patent. More interesting that developer omit any antifoggant (KBr, BZT etc)

    working solution 1+4 must be like to next:

    Potassium Sulphite 71g
    Hydroquinone 8.8g
    Phenidone 0.25g
    Borax 4.7g

    71g of Potassium Sulphite = 71/MW(K2SO3) = 71/156.26 = 0.4544M = 0.4544*MW(Na2SO3) = 0.4544*126.04 = 57.3g of Sodium Sulphite
     
    Last edited by a moderator: Mar 25, 2013
  7. Ian Grant

    Ian Grant Subscriber

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    The switch from Phenidone to Dimezon S in Ilford liquid developers seems to co-incide with the change in sub-contractors producing Ilfords chemistry.

    Older MSDS data for these developers is very much more informative, they show that Phenidone was used originally in DDX.

    Ian
     
  8. Rudeofus

    Rudeofus Subscriber

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    Be careful with that statement. Most common sequestering agents buffer in the pH range and DTPA is no exception (see page 6). Choosing a different sequestering agent can give you a different pH and buffer strength! Also note that the patent lists DTPA, while the MSDS lists DTPA pentasodium salt, the first one is a strong acid while the latter one is caustic (and much easier to dissolve). If pH is suitably chosen there is a good chance that no restrainer is needed.
     
  9. Relayer

    Relayer Member

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    Yes, you right. If we omit DTPA or change it to other agent we need correct (decrease) amount of borax for required pH=8.5. This isn't a provlem
     
  10. Rudeofus

    Rudeofus Subscriber

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    It's not only about pH, it's also about buffer strength! DTPA is a buffer at pH 8.5, if if we use less Borax in order to compensate for omission of DTPA, we create a much weaklier buffered developer.
     
  11. Relayer

    Relayer Member

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    hmm ... may be. but I think that amount of DTPA relatively low for change buffer capacity.
     
  12. Rudeofus

    Rudeofus Subscriber

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    That dev isn't exactly loaded with Borax either ...
     
  13. john_s

    john_s Subscriber

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    The Australian MSDS documents often contain more detail. For what it's worth, here is an extract from it:

    2. COMPOSITION/INFORMATION ON INGREDIENTS:
    NAME
    CAS No.: EINECS Nr.:


    2,2'-OXYBISETHANOL (Diethylene glycol)
    111-46-6 203-872-2
    5-10 %

    HYDROQUINONE
    123-31-9 204-617-8
    1-5 %

    1-PHENYL-4-METHYL-4-HYDROXYMETHYL-3-PYRAZOLIDONE (Dimezone-S)
    13047-13-7 235-920-3
    0-1 %

    DIETHYLENETRIAMINE PENTAACETIC ACID NA5
    67-43-6 200-652-8
    1-5 %

    SODIUM TETRABORATE
    1330-43-4 215-540-4
    1-5 %

    BORIC ACID
    10043-35-3 233-139-2
    1-5 %

    WATER
    30-60 %

    POTASSIUM SULPHITE
    10117-38-1
    30-60 %


    DENSITY/SPECIFIC GRAVITY (g/ml): 1.31 Temperature (°C): 20

    pH-VALUE, CONC. SOLUTION: 8.7