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  1. #1
    Ian Grant's Avatar
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    Modern Rodinal Substitutes Part II

    Apologies for having to start a new thread but I can't read or even access the first to reply to posts.

    So with a bit of telepathy

    Quote Originally Posted by Kirk Keyes View Post
    Well, there's a problem there, as it's really hard to measure pH accurately when it gets much above 12.5 or so. You have to start getting special electrodes and the like.

    But for MSDS work, it doesn't have to be too precise.
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    Kirk

    A point that's being missed is that A&O give a figure of 2.7% Potassium Hydroxide not 3% in older Agfa MSDS.

    The pH is around 14 sure, but the actual requirement is the pH of the working dilute solution rather than the concentrate which is given elsewhere as pH 11.55, which I commented on in the first post of the thread.

    Way back Ron (PE) mentioned adjustments to Rodinal before bottling, the question we need to ask is are they adjusting on the basis of the concentrate, or also doing some tests on a dilute sample, as this will be a far more accurate indicator.

    Can someone please post a link to this continuation on the original post.

    Ian

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    Gone through my other books and found the one: Laubert, Photographic Formulas and Tables, year 1917, 3d edition.

    There is also Rodinal Formula:
    Water 100ml
    Potassium metabisulfite 30g
    Paramidophenol 10g
    Add saturated sodium hydroxide solution until precipitate dissolves.

    In the beginning of the book there are comments about chemicals:
    Paramidophenol - this is p-aminophenol slat formed with HCl, so this is hydrochloride.

  3. #262
    Ian Grant's Avatar
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    I used Agfa's modern Rodinal for about 18 years and it never ever crystallised. I also used a lot of it as I was processing 120 but mainly large format negatives, that sounds like a temperature problem with Sulphite crystallising.

    There should be a very very small amount of crystallisation in the old Rodinal/Rodinal substitute formulae because that's how it's supposed to be made, no excess Hydroxide so just a trace of free base crystals.

    iAN

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    Quote Originally Posted by Photo Engineer View Post
    The crystals dissolve when more alkali is added. The pAP is a weak acid and needs a large amount of "excess" hydroxide to force the salt to dissolve by forming the Phenolate.

    PE
    That what I'm saying - Agfa's Rodinal has pH 14, and it does have crystals....
    If I make rodinal, it has pH<12, to make pH 14, I need to add more hydroxide, right? If I do that, pAP crystals dissolves very fast.....

    So, what are the crystals in Agfa's developer?

  5. #264

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    Quote Originally Posted by Ian Grant View Post
    I used Agfa's modern Rodinal for about 18 years and it never ever crystallised. I also used a lot of it as I was processing 120 but mainly large format negatives, that sounds like a temperature problem with Sulphite crystallising.

    There should be a very very small amount of crystallisation in the old Rodinal/Rodinal substitute formulae because that's how it's supposed to be made, no excess Hydroxide so just a trace of free base crystals.

    iAN
    Strange - I had three different bottles (from different batches), and all of them had crystals.

  6. #265
    Ian Grant's Avatar
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    Again Andresen's One shot p-Aminophenol formulae from the early 1900's, you see people saying they are different Formulae, but the ratio of p-Aminophenol to Potassium Metabisulphte is the samev 1 part p-Aminophenil to 3 parts Potassium Metabisulphite with add enough Hydroxide to just dissolve all the developer.

    Ian

    Quote Originally Posted by pavelt2tk0 View Post
    Gone through my other books and found the one: Laubert, Photographic Formulas and Tables, year 1917, 3d edition.

    There is also Rodinal Formula:
    Water 100ml
    Potassium metabisulfite 30g
    Paramidophenol 10g
    Add saturated sodium hydroxide solution until precipitate dissolves.

    In the beginning of the book there are comments about chemicals:
    Paramidophenol - this is p-aminophenol slat formed with HCl, so this is hydrochloride.

  7. #266
    Ian Grant's Avatar
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    Quote Originally Posted by pavelt2tk0 View Post
    Strange - I had three different bottles (from different batches), and all of them had crystals.
    Possibly bad storage not by you, the Russian Importer.Distributor. It keeps so well but then the temperatures in Russia do get rather low in the Winter

    Ian

  8. #267
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    Looking at the Sodium Benzenesulfonate further it's use is given in at least 4 Fuji Patents as an anti-oxidant, alongside other examples such as Suphites or Metabisulphites themselves and Ascorbic acid. It's also used in photothermography by some US companies..

    If Agfa did or do still use it then it's possible that anyone trying to analyse Rodinal might think Sodium Benzesulfonate or another similar anti-oxidant was an unidentifiable fevloping agent. Ilford patented some anti-oxidants in the 1950's presumably for use in Ilfosol originally a Phenidone/Glycin based developer, and these can also be used to form developing agents. (4-aryl-2-oxytetronimic acids).

    So thanks that's useful information.

    Ian


    Quote Originally Posted by pavelt2tk0 View Post
    BTW, Guys going through all this posts, I also tried to mix some Rodinal.

    I used this recipe:
    Sol A:
    water 500ml
    p-aminophenol 50g
    potassium metabisulfite 150g

    Sol B:
    water 300ml
    Sodium hydroxide 100g

    Sol C:
    water 50ml
    Potassium Bromide 5g
    Sodium benzenesulfonate 0.3g

    This recipe comes from Soviet Union the most known book, and states this as Foma R09 Rodinal recipe. The only difference - the formula asks for p-aminophenol hydrochloride or hydrosulfate), but looking at your discussion this is definitely the mistake. It must be the base.

    The principle is almost the same as usual - slowly add Sol B into Sol A, until precipitate almost dissolved.
    The add Sol C, and water to make 1l.
    Sodium benzenesolfonate is used to prevent oxigen diffusion into the solution. Greatly extends it life. Has no effect on the developer.

    Looks it is very similar in it's activity and properties to Agfa modern Rodinal, what is different - the color, it is very light when fresh.

  9. #268
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    It's not clear to me why we need the pH of the stock to be 14, or the pH of the working solution to be about 12. I wanted to see the effect of using ascorbic acid in place of sulfite as the oxygen scavenger. (You know me.) I knew from experience that ascorbate above pH 11 or so is rotten as a developer. It fogs fiercely unless a terrible amount of bromide is there. As an antioxident, it cam take up two moleclues of oxygen for each molecule. I did one of my Q&D experiments. 1 gram of p-aminophenol, 1 gram of ascorbic acid, and roughly 15 grams of K2CO3, starting with 7 (1 tsp. I actually weighed it.) in a liter, adding bits of the carbonate until the sediment dissolved. The pH was about 10.6. My pH meter reads 9.6 with saturated borax. This was a working strength solution.

    The results with FP4+ were quite good, about what would be expected from Rodinal at 1+25. 9 minutes at 69F gave a full scale negative of normal contrast.
    Attached Thumbnails Attached Thumbnails PAPCARBC from film.jpg  
    Gadget Gainer

  10. #269
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    The hike in pH seems to be mainly so Agfa could get more activity out of less developing agent cutting the cost of manufacture. This was what Edward Zimmermann and other photographers mainly German where complaining about in the past and why some prefer Calbe R09.

    In Europe, (less so in the UK) Rodinal has always been main stream developer, it was one of Agfa's main film developers, I've no idea how it sold in proportion to others.

    Are you saying that Ascorbic at pH 11 is the cause of the fogging ? Or is this not due to the fact that a high sulphite level's required as an anti-oxidant ?

    Ian

  11. #270
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    Quote Originally Posted by Ian Grant View Post
    The hike in pH seems to be mainly so Agfa could get more activity out of less developing agent cutting the cost of manufacture. This was what Edward Zimmermann and other photographers mainly German where complaining about in the past and why some prefer Calbe R09.

    In Europe, (less so in the UK) Rodinal has always been main stream developer, it was one of Agfa's main film developers, I've no idea how it sold in proportion to others.

    Are you saying that Ascorbic at pH 11 is the cause of the fogging ? Or is this not due to the fact that a high sulphite level's required as an anti-oxidant ?

    Ian
    I didn't use any sulphite in my Q&D trial. I did, however, try the same amounts of p-aminophenol and ascorbic acid with KOH as alkali. Total disaster. Very dense fog. pH was much higher than with carbonate. I attribute that to the fact that although the same number of K molecules is used in each case to form the aminophenolate, a little extra carbonate does not have the same effect on pH as a little extra KOH. The ascorbic acid becomes the nearly neutral ascorbate in both cases. Thus, the pH is practically all due to the potassium aminophenolate when carbonate is used.

    If ascorbic acid behaves with p-aminophenol as it is theorized to do with Metol, it will regenerate oxidized aminophenolate. By keeping the pH below the point where ascorbate is a developing agent, I should be able to increase the relative amount so as to extend the storage life of a stock solution greatly. If it is successful, it will probably be a great disappointment.
    Gadget Gainer



 

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