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  1. #11

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    Not CD2 or 3, but there is a formula I posted a while back which uses CD4.
    http://www.apug.org/forums/forum223/...developer.html

  2. #12
    Ian Grant's Avatar
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    PPD and other colour developing agents give very much finer grain so it's quite a different avenue of approach.

    Ian

  3. #13

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    You call PPD a color-developer?

    Not a word spelled about that in my copy of Die Neue Foto-schule I, Die Technik, Hans Windisch, 1954!
    But Hans has this pegged down firmly as a fine grain developer and quotes Sease III formula which is a little different from Sease I....

    Erik
    Last edited by Removed Account2; 10-14-2010 at 04:08 PM. Click to view previous post history.

  4. #14
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    Ascorbic acid is not in any way similar to PPD or CD-2.

    PE

  5. #15

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    Quote Originally Posted by Photo Engineer View Post
    Ascorbic acid is not in any way similar to PPD or CD-2.

    PE
    Granted but now PPD, CD-2, 3 and 4 are already floating in this thread, what are the similarities & dis-similarities between those already?

    A little rundown on developing agents, and not just links, please!

  6. #16

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    From Anchell & Troop p 67 "The amount of glycin in Sease 1,2,3 & 4 was respectively,none,1g,6g,and 12g.As glycin is increased,speed goes up,but fine grain goes down."

    To get the finest possible grain I would like to make the equivalent to Sease no 1 but I would like to know if to use 214.7 parts CD-2 or only half that,to replace 108.1 parts PPD.

    In Sease 1 both sulfite and PPD are grain solvents ,it seems to me that other additions like glycin or hydroquinone are not and are mainly there to speed things up a bit.

  7. #17
    Ian Grant's Avatar
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    Don't dismiss CD-3 too quickly, it's a weak developing agent but Kodak did publish a Super Fine Grain Developer using it in a Patent in 1940. They overcome the weaker activity by using Carbonate as well as Sulphite.

    The 1940's Kodak Patents for developers are quite interesting as they show some rather interesting avenues of research, Kodak had a set portfolio of developers etc it was harder for them to change the line up than smaller companies, so we only see gradual new introductions or replacements.

    Ian

  8. #18
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    Ok, Ascorbic Acid is a normal rather benign B&W developing agent. It has no special properties, but does often decompose unexpectedly and so the developers should be tested before use for potency.

    PPD is a very slow acting developer that gives fine grain and often low speeds, depending on formula. It is rather toxic and not too soluble. It tends to oil out and form black tars.

    CD2, 3, 4, and 6 are faster acting than PPD but similar in some regards. CD4 is the most soluble and CD6 and CD4 are the most active. CD2 is more toxic than 3, 4, or 6 and less soluble. But it is less toxic than PPD. I would pick CD2, CD4 or CD6 to design a new B&W developer but would not use any of the existing formulas. There were several improvements on the books at EK that never saw the light of day. Go for it!

    Ian's post above is quite correct and I am aware of work in that regard and some that went beyond the patents.

    PE

  9. #19
    Ian Grant's Avatar
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    Quote Originally Posted by Erik Prestmo View Post
    You call PPD a color-developer?

    Not a word spelled about that in my copy of Die Neue Foto-schule I, Die Technik, Hans Windisch, 1954!
    But Hans has this pegged down firmly as a fine grain developer and quotes Sease III formula which is a little different from Sease I....

    Erik
    PPD is a weak colour developing agent, even weaker is p-aminophenol

    My "The New Photo School" is in English 1938 First 1- 10,000 Edition, although I also have a German 1944 edition.

    Ian

  10. #20

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    Quote Originally Posted by Ian Grant View Post
    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
    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.

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