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

    The formula for Rodinal R09 has never been officially published by Agfa. In the "Agfa" Book of Photographic Formulae, published by the Berlin Aniline Company in 1910, the company tells us:

    As "AgfA"-Rodinal contains only traces of carbonic alkalies, the use of distilled water for dilution is not necessary. In connection with the use of "Agfa"-Rodinal the following remarks should be carefully noted:

    In addition to neutral sulphite and water "Agfa"-Rodinal contains only an alkaline salt of Paramidophenol, but no excess of caustic alkali.

    PDF Rodinal 1910

    However it's possible to make formulae that's close to the current versions.

    Original Rodinal contained p-Aminophenol (once called Paramidophenol by Agfa) and this was formed by precipitation of the free base from p-Aminophenol hydrochloride using sulphite and carbonate (hence Agfa's comment "contains only traces of carbonic alkalies".


    The formula for Rodinal has changed and evolved presumably as high grade p-Aminophenol free base became commercially available, allowing Rodinal to be completely free of carbonates.

    J. Desalme published a " Concentrated Paraminophenol Developer of the Rodinal Type" in 1913, this was later included in L.P. Clerc's book "Photographic Theory and Practice".

    Sodium Carbonate & Sodium Sulphite are added to a solution of p-Aminophenol Hydrochloride which precipitates the free base, which is filtered and collected.

    The paste of p-Aminophenol free base is then added to a solution of Sodium Metabisulphite and Sodium Hydroxide added until all the free base is dissolved, finally a small amount of Metabisulphite is added until the first crystals of p-Aminophenol free base begin to form again.

    This mirrors Agfa's own description of early Rodinal, and accounts for the traces of carbonates, and the "no excess of caustic alkali". (J. Desalme was a photographic chemist specialising in aminophenols and other developing agents particularly for colour processing).

    Now we reach a point of contention "Free base" or "Hydrochloride", genuine Rodinal has always been made using the Free base of p-Aminophenol . (50g of p-Aminophenol is equivalent to 66.2 g p-Aminol hydrochloride). There is no evidence to suggest that Rodinal of any form has ever contained p-Aminophenol Hydrochloride.

    The MSDS sheets for both Rodinal and Calbe R09 show clearly that both developers contain p-Aminophenol free base (CAS 123-30-8) and not p-Aminophenol hydrochloride (CAS 51-78-5).

    Making a Rodinal substitute with p-Aminophenol Hydrochoride will leave free chlorides in the solution, and neutralise more Hydroxide, the amount of developing agent would need to be increased along by a factor of 1.33 and also more KOH added.

    Data on early Rodinal is hard to find but in a thread on Photo.Net "Edward Zimmermann" wrote:

    The formulas for Rodinal, resp. R09 (1964 to present), have never been published. The patent is for Paramidophenol developers and there are many recipes making the rounds since the late 1800s. One of the most famous is attributed to Eder. From my copy of Spörl and Neumann, "Fotografisches Rezeptbuch" 1943 edition, p.50):

    N16:

    • Paramidophenol 50g
    • Kaliummetabisulfit [Potasium Metabisulfite] 150g
    • Wasser 625ccm (ml)

    Then a solution of

    • Ätznatron [Sodium Hydroxide] 215g
    • Water 500ccm (ml)

    is slowly added untill the cloudyness breaks. According to the book it says this is typically around 350ml.
    Then the solution is diluted with water to make 1 liter.

    My note: 350ml of the Sodium Hydroxide solution contains 150.5 gms Sodium Hydroxide.

    The same formula was published in the British Journal Photographic Almanac (1910 & earlier) as:

    Paramidophenol.
    ONE-SOLUTION

    Potassium metabisulphite 300g
    Distilled water 1 litre
    Paramidophenol 100g

    Dissolve in the above order and add gradually:
    Caustic soda or potash to dissolve the precipitate first formed.

    For use, dilute 1 part. with 10-20 parts of water.

    No final volume of solution is given but it's likely to be 2 litres if you want the equivalent of early Rodinal.

    It's important to note that these sources clearly indicate the use of the free base, as they go on to also include p-Aminophenol Hydrochloride film developers. These are in the 1910 "Agfa" Book of Photographic Formulas, the 1910 BJP Almanac and Ed Zimmermann's book all from quite different sources & countries.

    However other versions of this formula appear in various books from the early 1900's onwards, but using p-Aminophenol Hydrochloride, because of the difference in Molecular Weight and the effects of the additional Hydrochloride they won't be quite the same. Dr M. Andresen, of Agfa, who discovered & patented p-Amaninopheol and designed Rodinal published it himself in the "AGFA Photo-Handbook" he did not claim it was similar to Rodinal, listing it as - Formula 21: Concentrated single solution. (As above proportions but using p-Aminophenol Hydrochloride).

    L.P.Clerc and others indicate that Potassium Metabisulphite was the preferred source for the Sulphite in Rodinal, Potassium salts are used in preference to Sodium because of their greater solubility in water which becomes far more important in concentrated developer solutions. Metabisulphite and Hydroxide form Sulphite in solution.

    At some point before or during WWII Agfa began using Potassium Sulphite and also adding Potassium Bromide and an anti-foggant to Rodinal. It's entirely possible that Agfa modified Rodinal so that it was more suitable for roll & particularly 35mm films which became cfommon in the 1930's.

    Some have made the assumption that this formula might be "Classic Rodinal" but if we compare it to a modern MSDS's it's only close s to Calbe's R09 MSDS for the p-Aminophnol.

    P-Aminophenol 50g - 5%
    Potassium Metabisulphite 150g - 15%
    Sodium Hydroxide - very approx 150g - 15%
    Water to 1 litre

    Calbe R09 MSDS

    P-Amininophenol 5%
    Potassium Sulphite 30%
    Potassium Hydroxide 4%

    However Potassium Metabisulphite is quite acidic in solution and will neutralize a considerable proportion of the Hydroxide. Replacing it with Potassium Sulphite cut's the amount of Hydroxide needed very substantially. Potassium Metabisulphite 5% solution has a pH of 3.8 - 4.6, while a similar Potassium Sulphite solution has a pH of 9 - 10

    Only one parameter seems to stay constant from early published alternatives through to Orwo/Calbe R09 - the fact that Rodinal is a 5% solution of p-Aminophenol free base in a sulphite solution, with no excess of alkali. It's reported that the Calbe product usually has a few crystals of the free base in the bottom of the bottle, which indicates no excess of Hydroxide.

    The British RAF report into the "Agfa Film Factory - Wolfen" reported by G.C. Brock, London : H.M.S.O. gives a formula for Rodinal as:

    Dissolve 34 kg of para-aminophenol in 340 litres of water. Add 558 kg of a 30% solution of potassium sulphite at 55C followed by 50 kg of a 34% potassium hydroxide solution, then 5.52 kg of potassium bromide in a little water. Add 42 g P.1347 (an Agfa-specific anti-foggant). Filter and allow to stand for 14 days.

    Knowing the Specific Gravities etc this seems to be around:

    p-Aminophenol 34kg
    Potassium Sulphite 128.08kg
    Potassium Hydroxide 12.57 kg
    Potassium Bromide 3.75 kg

    We aren't given a final volume, but if we relate this to the 5% p-Aminophenol of the Calbe MSDS this works out as:

    p-Aminophenol 5%
    Potassium Sulphite 19%
    Potassium Hydroxide 1.85%
    Potassium Bromide 0.77%

    But the Calbe/Orwo version of R09 is the pre-WWII formula and it's MSDS is

    p-Aminophenol 5%
    Potassium Sulphite 30%
    Potassium Hydroxide 4%
    Potassium Bromide - not included (below 1%)

    Unfortunately we can't really completely trust the RAF report, none of the Allied F.I.A.T. reports about Agfa products is entirely accurate, after all some Agfa employees were former members of the National Socialist Party (Nazi's). There is insufficient Potassium Hydroxide to react with the p-Aminophenol free base, and it is possible the resulting solution was then adjusted until the free base had just fully dissolved.

    Patrick "Gadget" Gainer has published "EZ Rodinal" which in terms of its ratio of p-Aminophenol to Potassium Hydroxide is probably close to Calbe R09 as there will be no excess of Hydroxide, the weights in brackets have been scaled to give a concentration of 5% p-Aminophenol.

    EZ Rodinal

    To 400 ml water, add:
    Sodium sulfite (anhyd) 85 g (106.3)
    p-Aminophenol base 40 g (50 g)
    Stir well. Add
    Sodium hydroxide 13.8 g or Potassium hydroxide 19.2 g (24g)
    Add water to make 500 ml. (1 litre)

    If EZ Rodinal; is adjusted a little further by adding 300 g of Potassium Sulphite in place of the Sodium Sulphite, some Potassium Bromide added plus some Benzotriazole and Potassium Hydroxide added slowly until the free base just dissolves

    EZ Rodinal New (Calbe R09 substitute)

    To 800 ml water, add:
    p-Aminophenol base 50 g
    Potassium sulphite (anhyd) 300 g
    Potassium hydroxide 24 g
    Potassium Bromide 0.8 g
    Benzotriazole 1% 10 ml
    Water to make 1 litre)

    This would be a lot close to the pre War formula and Calbe RO9, although this is itself now being made in a more concentrated form so that the dilutions & dev times are more comparable to Agfa /A&O Rodinal (post 1964)

    Patrick's second Rodinal substitute formulae is close to the Bayer/Agfa/A&O MSDS data-sheets for modern Rodinal:

    p-Aminophenol 4.1% (A&O)
    Potassium Sulphite 30-40%
    Potassium Hydroxide 2.7% (A&0)
    Potassium Bromide 1-5%
    Anti-foggant - not specified
    pH 14

    Gainer Rodinal Substitute

    To about 750 ml of water at room temperature, add
    p-Aminophenol 38 g
    Sodium sulfite (anh) 160 grams
    Sodium hydroxide 23 grams
    Water to 1 liter.

    This is on the right track, you need to use the free base and an excess of Hydroxide unlike the older R09 formula which has nearly 20% more p-Aminophenol and also requires using at a higher concentration to get equivalent results.

    In a post about Patrick's version a comment was made about the pH at 1:50 being roughly 11.6, Agfa Rodinal has a stock concentrate pH of 14 and a dilute pH of 11.55 so if this is the case Patrick's formula is about right, except too little Sulphite and there's no Bromide or anti-foggant.

    Agfa's modern Rodinal 1964 onwards uses an excess of Hydroxide and as a consequence is more active despite the lower level of p-Aminophenol than the previous formulae. Calbe R09 concentrate has a pH of 11.8.

    This is what I would use as a starting point for a good modern substitute:

    Rodinal Substitute

    p-Aminophenol.(free base) ................... 41 g
    Potassium sulphite (anh) ..................... 348 g
    Potassium Hydroxide ........................... 27 g
    Potassium Bromide ............................. 10 g
    Benzotriazole 1% ............................... 10 ml
    EDTA Na4 (optional) ........................... 6 g
    Water to make .................................. 1 litre.

    If necessary adjust to pH 14

    Some notes:
    The balance of the Bromide & Benzotriazole may need adjusting upwards..
    The mixed developer should be left a couple of weeks before use.

    Contrary to what has been written in some books Rodinal has always used the free base of p-Aminophenol although in the early days this was prepared from the Hydrochloride first.

    Ian

  2. #2

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    Many thanks.

    This is indeed quite useful information. Especially if I ever use up all the bottles of Rodinal I have stored in the basement…

  3. #3
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    Some thoughts are appropriate here:

    It was known that real Rodinal did not require a filtration step to prepare. This is one of my balking points with some of the formulas. It was made in-situ with no filtration. If you didn't know this fact, sorry to spring it now. In addition, there was a final ingredient added just as the material was packed into the bottles for shipping. Sorry again if you did not know that!

    Going back to the formulas posted on the other thread, they seem to be quite alkaline, as much as 11.x and these current formulas seem to be more neutral. So, I ask, which is correct. This is more or less rhetorical as it won't help much except to know the "correct" pH, not what got us there.

    And, use or even the exact amount of Metabisulfite used will tell us nothing about the final product as the M will rapidly decompose into Sulfite, Bisulfite and a mix of Sulfates in addition to any reaction with the p-Amino phenol.

    PE

  4. #4
    Ian Grant's Avatar
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    Fair points.

    First early Rodinal contained traces of carbonates from the precipitation of the free base, and it was known Agfa were starting with the Hydrochloride. We won't know exactly what stage, how or for how long they had to do this but at some point the free base was made and purified commercially.

    Potassium Sulphite solution has a pH of 9-10 and Calbe RO9 has a concentrate pH of 11.8 which clearly indicates there's not much if any free Hydroxide which is Agfa's claim for Rodinal right from it's early days "Agfa"-Rodinal contains only an alkaline salt of Paramidophenol, but no excess of caustic alkali." So a substitute for R09 should only need enough Hydroxide to form the alkali p-Aminophenolate which will of course affect the pH.

    Modern Agfa Rodinal uses an excess of hydroxide so has a pH of 14, a solution of 0.5% alone has a pH of 13 and there is more free Hydroxide than that in the formula which along with the sulphite & alkaline p-Aminophenolate will take the pH to around 14.

    I'm not suggesting using Metabisulpite, that was an early method used but requires far more hydroxde to first neutralise it and then form the sulphite, Dr M. Andresen (Agfa) certainly used metabisulphite as the source of Sulphite in some of his formulae, and other contemporaries were doing the same. The major issue is the amount of hydroxide needed will vary depending on the condition and free SO2 content of the powder or solution. This just adds an other unnecessary variable.

    It's quite probable that RO9 may need final adjustments prior to bottling at a commercial level. One reason Agfa in West Germany changed the formulae was to make it cheaper & easier to manufacture, by using excess Hydroxide the step needed to balance the p-Aminophenol against the hydroxide has been eliminated and also allows a lower concentration of p-Aminophenol to be used while actually increasing the developer's activity.

    Ian

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    Again, good points Ian. I appreciate the discussion. I have been fascinated by Rodinal for years.

    I might add that I was toying with the idea that Agfa used the HBr salt of the p-AP to get the Bromide in the final developer, as the Chloride might be a variable that they did not want. OTOH, the Chloride may have functioned as it does in Microdol X to an extent adding its solvent powers to the Sulfite. IDK. All fascinating.

    The final step was indeed a pH adjust due to the fact that the "system" was in an unbalanced state for hours after mixing for some reason and had to be rebalanced. This was one of the sticking points of Rodianl manufacturing.

    PE

  6. #6
    Ian Grant's Avatar
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    Rodinal has always used the free base in the developer itself, right from it's initial formulation, Dr Andresen's contemporaries were well aware of this. It certainly appears they didn't want the Chlorides present in the developer.

    If I was making a developer like the old type Rodinal, Calbe R09 or similar, on a commercial scale I think I'd mature it with a very slight excess of Hydroxide, and then use a small addition of Potassium Metabisulphite to remove the excess hydroxide. You could back titrate a sample to determine the exact amount to add, once there's no excess hydroxide the free base begins to precipitate, but the pH will also probably drop at the same time. It's hard to know without trying it.

    Judging from Patents on p-Aminophenol manufacture it appears there must also have been issues with controlling the purity during manufacture, so possibly other tests were conne before finalmadjustments & bottling.

    Commercial alternative p-Aminophenol developers were available by the early 1900's Johnson's Azol was an early alternative to Rodinal, again using the free base. Ilford introduced it's version Certinal in 1909

    Kodak's approach was to use p-Aminophenol Oxalate, they sold this as Kodelon and presumably it's the developing agent in "Kodilon" which was their highly concentrated liquid developer, and competitor to Rodinal. Kodak also sold p-Aminophenol hydrochloride as Kodelon. I have only ever seen references to "Kodilon" in UK Kodak Formulary as a commercially available liquid para-aminopheol type developer.

    It appears when p-Aminophenol hyrochloride is used in combination with a second developing agent and excess carbonate there's less of an issue with the Hydrochloride, and it was used in other Agfa, Kodak, Ilford etc developers.

    Lowe used "Gradol" which was the Edwal company name for p-Aminophenol Sulphate.



    I deliberately didn't give the formula for J. Desalme's "Concentrated Paraminophenol Developer of the Rodinal Type" because there are some issues with the weights & conversions & concentrations used in the British translation of L.P.Clerc's book. The UK editor of the book George E. Brown, the Editor of The British Journal of Photography, and also the British Journal Photographic Almanac, died in 1934, and the book wasn't published until 1937 some considerable time after his death. (It is a large and comprehensive book). G.E. Brown was the Tangye Scholar for Chemistry 1892-3, at Birmingham University and would have had a full understanding of Photographic Chemistry.

    However Brown also published the same formula in the British Journal Photographic Almanac.

    Paramidophenol Developer

    Solution A

    Paramidophenol hydrochloride 68 g
    Water, hot, 600 - 700 ml

    Filter solution if necessary.

    Solution B

    Sodium Sulphite 9.36 g
    Sodium Carbonate (anhyd) 31.2 g
    Water to 200 ml


    Add B. to A. The paramidophenol is thrown down.
    When mixture is cool filter off the deposit on cloth, and let the paste dry until its bulk is not more than 300ml.

    Then, in a graduate, mix with it 100 ml of soda bisulphite lye 35° B. and add strong solution of caustic soda of 40° B. (about 50%) until the base is just dissolved. Water is then added to make 500 ml. The solution is diluted 20 to 30 times for use.

    Sodium Metabisulphite (soda bisulphite) and Sodium Hydroxide (caustic soda( were commonly sold as a solutions.

    The Sodium Metabisulphite 35° B, is approx a 28-30% solution and it is still commercially available in this form.
    The Sodium Hydroxide 40° B, is closer to 38% than the 50% given.

    The yield of p-Aminophenol free base is approx 50.97 if conversion 7 recovery is 100%.

    The Avoirdupois & Metric conversions/proportions are correct, this formula uses about 10% of the metabisulphite advocated in other similar formula which allows a higher concentration of the developer.

    I've only added it to the thread to show how easily the free base can be formed.

    Ian

  7. #7
    gainer's Avatar
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    I set out to try your formula. I found I had little more than 300 grams of Potassium sulphite left. It's s a good thing, because that amount would not dissolve in a liter of hot water. I added 27 grams KOH next, and then 41 grams of p-aminophenol base. I can't tell if the sediment is all sulphite, but the color is light orange to my 82 year old eyes. A snip test of 1+50 dilution seemed about normal. It looks about like a batch I made a while ago that has still not turned the deep brown, but nevertheless works very well.

    Have you tried dissolving 384 grams of anhydrous Potassium Sulphite in a liter of water? I have heard that number before, but it doesn't appear in my CRC Handbook. My sulphite came from Photographers' Formulary.

    I'll look at it again tomorrow and do a test roll.
    Gadget Gainer

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    I have no idea what you guys are talking about, but find it awesome and fascinating.

  9. #9
    Ian Grant's Avatar
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    Quote Originally Posted by gainer View Post
    I set out to try your formula. I found I had little more than 300 grams of Potassium sulphite left. It's s a good thing, because that amount would not dissolve in a liter of hot water. I added 27 grams KOH next, and then 41 grams of p-aminophenol base. I can't tell if the sediment is all sulphite, but the color is light orange to my 82 year old eyes. A snip test of 1+50 dilution seemed about normal. It looks about like a batch I made a while ago that has still not turned the deep brown, but nevertheless works very well.

    Have you tried dissolving 384 grams of anhydrous Potassium Sulphite in a liter of water? I have heard that number before, but it doesn't appear in my CRC Handbook. My sulphite came from Photographers' Formulary.

    I'll look at it again tomorrow and do a test roll.
    Patrick, photographic grade Potassium Sulphite is sold as a 45% w/w solution, so 384 will dissolve easily, but maybe not quickly

    It's solubility in water is 655 g/l, substantially higher than 384, this is why Potassium salts are used in liquid concentrate developers

    In fact the supplier I'm looking at doesn't sell photographic grade Potassium Sulphite as a solid instead 45% W/W containing approx 450g/l:

    STANDARD PACKING:

    * 250 Kgs. HDPE Drum
    * 30 Kg. HDPE carboys
    * 1000 Liters Intermediate Bulk container (IBC)
    * 20 MT Bulk Liquid Bag (Flexi bag)

    In Germany BASF supply this grade, in the US Mallinckrodt Baker, it's standard.

    So to answer your question, yes I have made up concentrated stock solutions of Potassium Sulphite and Carbonate. I've started using the Potassium salts when making up concentrates of my print developers, replacing Sodium Sulphite & Sodium Carbonate in the formulae with the Potassium salts and KOH. This is done commercially to allow higher concentrates which won't precipitate during storage.

    Ian
    Last edited by Ian Grant; 08-23-2009 at 04:16 AM. Click to view previous post history. Reason: add

  10. #10
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    "Patrick, photographic grade Potassium Sulphite is sold as a 45% w/w solution, so 384 will dissolve easily, but maybe not quickly."
    How about overnight, starting in 160 F water? I stirred it for a good half hour before going to bed. That doesn't explain what happened here. This morning, I decanted clear liquid and found that another liter of water was required to dissolve the remainder. That solution is quite a potent developer, but not as strong as what I decanted.

    The CRC Handbook shows K2SO3.2H2O, with solubility in cold water of 1000 g/l. My 320 g/l certainly should have dissolved, even if I had the anhydrous, in the hot water.
    Gadget Gainer

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