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  1. #1

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    Identification of Ilford 1+9 PQ paper developer formula

    Hello

    In patent US5376510 from Ilford Limited I was found next formula:

    Water 875ml
    Na5DTPA 37% 35ml (=13g)
    Sodium sulfite 120g
    Potassium carbonate 150g
    Hydroquinone 35g
    Dimezone S 2.5g
    Potassium bromide 7g
    Benzotriazole 0.3g
    Sodium hydroxide 67% 12ml (=8g)
    pH(1+9)=10.8

    Total volume of solution isn't specified in patent. I think that its will be in range 950..1000ml.
    Is this Ilford PQ Universal formula? Multigrade? or something else?

  2. #2
    Rudeofus's Avatar
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    An easy test to confirm or disprove this would be measuring pH and buffer strength of this recipe vs. original product ...
    Trying to be the best of whatever I am, even if what I am is no good.

  3. #3

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    Research MSDS - in PQ Universal, Multigrade, Harman cooltone amount of potassium carbonate specified as 5-10%. In formula from patent - 15%

  4. #4

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    A patent is a two edge sword for companies. While it protects some rights it also can reveal information that a company does not want to see published. A formula cannot be patented and therefore companies maintain them as trade secrets. To this end they resort to all sorts of tricks such as the use of obscure chemical names, omitting important ingredients; to the outright use of deliberate errors. So the referenced formula may not be accurate nor may it be the optimum combination of ingredients. Its purpose is only to demonstrate a particular claim in the patent. Care must be used is assigning a particular formula to a specific commercial product. In addition a company may make unannounced changes to a product once it reaches the market.
    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

  5. #5
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    Here is a formula for Ilford PQ Print Developer I got out of a folder I was given with many formulae in:
    Sodium Sulphite anhyd. 110.0 gm
    Hydroquinone 31.0 gm
    Phenidone 1.28 gm
    Potassium Carbonate anhyd. 100.00 gm
    Sodium Hydroxide 2.0 gm
    Potassium Bromide 5.0 gm

    Water to make 1 Litre
    Dilute 1+9 for use

    It works very well and gives a good black on 'Old'papers.
    An 'Old Dog still learning New Tricks !



 

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