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  1. #21
    Ian Grant's Avatar
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    A big issue with developers is that manufacturers like Ilford, Agfa and Kodak could only sell so many types otherwise the sales & marketing was self defeating.

    So there's a vast number that never made the cut archived away. Sometimes other companies beat them to it with Patents, I'm fairly sure that's what delayed Xtol (or an Xtol type developer) as there was an early 60's US Patent held by a Swedish company and Xtol only appeared after that had expired.

    Sandy King's Pyrocat HD (and MC) are close variations of earlier Ilford Patent & a commercial developers, although used at much higher dilution and arrived at entirely independently. Kodak patented a similar Pyrocatechin/Ascorbic developer in the 40's but again ratios differ. There's only so many combinations ratios etc but many have been neglected or pushed back.

    Kodak spent years after it's introduction trying to improve D76, but as it had become a standard it was near impossible, they had to stick to close variants, that's still the case today with both D76 & ID-11 only th buffering differs from the original. Others did improve it - Agfa/Agfa Ansco and Adox (Dupont) but then they were entirely different dvelopers.

    Ian

  2. #22
    Ian Grant's Avatar
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    All the same company ultimately as Dupont took over Defender and Dr Sease designed them all

    There was a pre WWII link with Ilford, Dupont supplied them film base but there was also some shared research, and Dupont's first Varigram was based on Ilford Multigrade, although actual production of Ilford's product was delayed because the UK was already at war unlike the US.

    Ian

    Quote Originally Posted by nworth View Post
    DuPont ND-3, and Defender 15-D (also Sease NH-3) are similar developers falling somewhere between Sease No.2 and Sease No. 3. They contain more sulfite than the regular Sease formulas and 2 grams of glycin (compared to 1 or 6 for Sease 2 and 3). These developers have a good reputation for a compromise between ultra-fine grain and good sharpness. I understand that Sease No. 1, aside from drastically reducing film speed, produces rather mushy results. I've had good success substituting CD-2 for PPD in a couple of formulas, although not these. CD-2 seems give somewhat more film speed than PPD. CD-3 sounds like an expensive option.

    DuPont ND-3 Fine Grain developer
    For 35 mm film, sheet film, and similar negative material
    Water (52C) 750 ml
    Sodium sulfite (anh) 80 g
    Paraphenylene diamine base 10 g
    Glycin 2 g
    WTM 1 l
    Give negative 2 to 3 times normal exposure. Develop old film 10 to 17 minutes at 20C.

  3. #23

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    It's like a wine list.

    CD-4 MW=292.35
    www.chemblink.com/products/25646-77-9.htm

    Anchell and Troop and other references note that PPD is a grain sovent.
    I wonder if it is known if these CD compounds are grain solvents (as well as being developers).
    CD-4 seems to have a lot going for it.

  4. #24
    eclarke's Avatar
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    Are you in the US? I just got 2 pounds of ppd from Formulary (as an aside, I use a lot of this and the stuff I just got from them is the best I ever bought, finely milled and dissolves very well)...Evan Clarke

  5. #25
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    As has been noted, these developing agents vary so much in activity that there is no molar equivalency. Also, some formulas call for the free base and some of you are discussing the acid salts which will give a much lower pH than the free base. So, please be careful.

    Activity is roughly CD4, CD6, CD2, CD3 with PPD somewhere in the middle of that, all things being equal. They are ranked roughly highest to lowest in activity from my own personal experiments of the 4 Color Developers. I have done no process work with PPD.

    PPD's silver halide solvent ability is weak if it even has any. I have really forgotten the data, but it did not stand out as did Sodium Sulfite. In fact, PPD must be used with Sulfite to get much activity at all, even if you adjust for pH. It achieves the fine grained nature by being so slow and gentle. In fact, HQMS (Hydroquinone MonoSulfonate) is similar in that it is a fine grain developing agent by virtue of being slow. It is used in E6. Those that mistakenly use HQ in E6 first developer thereby lose this property.

    Going off on a tangent is not bad or good when designing a developer and can be very rewarding, but it is often complex and filled with trial and error. It is an art.

    PE

  6. #26

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    When used alone PPD causes a severe loss of film speed and acutance. Because of this another developing agent was added to most formulas, metol, glycin, ... Of course this sort of negates the use of PPD in the first place because the grain is increased again.

    Kodak published a formula for a special B/W developer based on CD-3 or CD-4. Its name began with SD rather than just D. Can't remember the number, SD-4?

    Probably the best starting point for a CD-3 developer would be the Crawley FX-10 formula.

    FX-10 Super Fine-Grain Developer

    Diethyl-p-phenylenediamine bisulfite 6.0 g
    Sodium sulfite, anhydrous 100 g
    Hydroquinone 6.0 g
    Borax 4.0 g
    Boric acid 4.0 g
    Water tp make 1 l

    Use full strength
    The BJ says develop for 8 min @ 65 F

    I would adjust for the difference in MW's, you might have to make a small adjustment in the ratio of borax to boric acid.
    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

  7. #27
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    Jerry;

    You do not have to lose speed though with the right formula.

    And, since the above formula uses the bisulfite salt of CD2, the pH will have to be tweaked if you change developers say by using the Sulfate salt of CD2. This is the fundamental problem here. Without pH values, the formulas are vague. Without the same salt, same thing applies.

    I'm not saying it cannot be done, just that the level of difficulty goes up and the tinkering goes up!

    PE

  8. #28

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    Quote Originally Posted by Ian Grant View Post
    So there's a vast number that never made the cut archived away. Sometimes other companies beat them to it with Patents, I'm fairly sure that's what delayed Xtol (or an Xtol type developer) as there was an early 60's US Patent held by a Swedish company and Xtol only appeared after that had expired.
    According to Mason, ascorbic acid was identified as a developing agent by Ohle in 1932, BP 430,264. I think the use of ascorbic acid as a practical developing agent depended more on the availability of a cheap method of synthesis.
    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

  9. #29

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    Quote Originally Posted by Photo Engineer View Post
    Jerry;

    You do not have to lose speed though with the right formula.
    Granted, but loss of speed is the reason for using an additional developing agent which causes the loss of much of the fine grain character of a PPD developer.

    Probably the best combination of speed, grain, and acutance is given by an ascorbate developer such as Xtol.
    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

  10. #30
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    Vitamin C was first synthesized in 1934.

    PE



 

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