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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. #31
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    Quote Originally Posted by Photo Engineer View Post
    According to my textbooks, the dihydrate can be rapidly oxidized to the sulfate if not tightly capped. It therefore appears to be less soluable as Potassium Sulfate is less soluable.

    Might be a thought to consider.

    Also, 50% by weight is an incomplete spec in this case. Due to the high solubility of some items the full spec of wt/vol or wt/wt must be used for accuracy.

    PE
    Ron, dad blamit, I was not saying we need a 50% solution for the Rodinal expedient. I was saying that if I could not get 100 grams of what I have to dissolve in 100 grams of water, there is something wrong with what I have in the container labelled "Potassium Sulfite." A 28% wt/wt solution would be just ducky, but I couldn't even get that.
    Gadget Gainer

  3. #32
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    Patrick;

    I was giving you a possible answer. It might have oxidized to Potassium Sulfate which is much less soluable! Thats all.

    PE

  4. #33
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    More motes on Rodinal & the FDC

    Reading the Film Developing Cookbook it's apparent that there are misconceptions about the "Rodinal Type" developer listed and Agfa Rodinal of all vintages over the years.


    1. First the date is given as 1881 but Andresen didn't discover p-Aminophenol until 1888, Rodinal came on the market in 1891.


    2. Rodinal has always been a p-Aminophenol developer using the free base, although in the early years the hydrochloride was used to prepare the free base.


    3. Rodinal (except Agfa after 1964) has always used Potassium Sulphite and just enough Hydroxide to form p-Aminophenolate, and no excess. The level of Hydroxide was increased by Agfa in their 1964 re-formulation, not decreased.

    The FDC states that "Agfa Rodinal still contains p-Aminophenol and Potassium Hyrdroxide but in much smaller amounts". The Major change in 1964 was an increase in the Hydroxide taking the concentrate pH from 11.8 to 14, at the same time the amount of developing agent was cut by approx 20%. The FDC makes no reference to the continued production of the older formula by Orwo/Calbe so no comparison.

    It's easy to see where this misunderstanding comes from. As Agfa themselves stated around the beginning of last century "In addition to neutral sulphite and water "Agfa"-Rodinal contains only an alkaline salt of Paramidophenol, but no excess of caustic alkali".

    The older formula (in the FDC and in the first post in this thread) uses 100 g of p-Aminophenol and 300gms of Potassium Metabisulphite, and about 216ml of a 400ml 50% Sodium Hydroxide solution (107.95 g) to form a 50/50 mix of Sodium and Potassium Sulphite (170.1 g + 213.5g). A small additional amount of Sodium Hydroxide is used to convert the p-Aminophenol free base, and slightly more for the Hydrochloride.

    Agfa stopped using Metabisulphite as the source of the Sulphite sometime before WWII and began using Potassium Sulphite instead, probably for economic reasons, the direct replacement in the FDC formula would be 427.11g, the amount of Hydroxide needed would fall to around 50g, a bit more if you use p-Aminophenol Hydrochloride rather than the free base.

    It's the amount of Hydroxide in the final developer that's important, rather than any used to convert Metabisulphite to Sulphite which completely disappears in the process anyway.

    One molecule of Potassium Metabisulphite and two Potassium Hydroxide react to give two Potassium Sulphite and water


    4. Bromide and anti-foggant.
    In the FDC Page 59 (Agfa Rodinal - 1964 onwards) Bill Troop states that "Potassium Bromide has also been added, which would not be necessary if p-Aminophenol was the sole developing agent"

    However we know that Agfa were already using Potassium Bromide and another anti-foggant (P.1347) many years earlier in Rodinal from F.I.A.T. and British RAF reports, they were probably introduced during the 1930's, so the statement doesn't make sense. The amount of Bromide then works out at less than 1% (0.77%) so would not be shown on Calbe's MSDS if they use a similar level.

    There are unsubstantiated reports that that the formulae Andresen himself published can sometimes cause Dichroic fog, whether this is due to the use of the Hydrochloride or incorrect balancing of the alkali by adding excess we can't know.

    But an increase in the alkalinity particularly as it's a hydroxide will greatly increase the potential for fog even more so because there's such a low level of sulphite and we know that dilute Agfa Rodinal has a higher pH than even the Calbe R09 concentrate, before that drops itself with dilution.


    5. If Agfa Rodinal is added to Bill Troop's table of High Acutance developers on page 59 of the FDC then a 1 in 50 working solution would fit extremely nicely alongside Beutler etc

    P-Aminophenol 0.82 g
    Potassium Sulphite 6.8g
    Potassium Hydroxide 0.12

    There's about 6 g per litre free Potassium Hydroxide in Agfa Rodinal concentrate and the p-Aminophenolate is also alkali so the pH is somewhere around 11.55 even when diluted 1+50, (Agfa's own pH figure).

    In comparison Calbe R09 needs to be used at 1 in 40 to achieve roughly comparable results and in this case we would have:

    p-Aminophenol 1.25 g
    Potassium Sulphite 6 g

    Relying on the alkalinity of the phenolate itself the pH will be much lower than Agfa Rodinal which is why over 50% more developing agent is needed.


    6. We do know the precise amount of p-Aminophenol in Rodinal, it's in the MSDS along with the Hydroxide, 4.1% and 2.7%, also all Rodinal MSDS's etc confirm it's the free base, typical German precision.

    Although Agfa Rodinal has nearly 20% less developing agent than Calbe R09 (old Rodinal formula) it's working at a much higher pH

    So these facts rule out Bill Troop's speculation in the FDC & on the Internet that a second developing agent has been added. p-Aminophenol shows good additivity & super-additivity with other developing agents so add even a trace at Agfa Rodinal's high pH's and the increase in activity would take Rodinal into a completely new realm hitherto unexplored which more than compensates.

    The FDC Rodinal type dev will work better with 133.4 g of p-Aminophenol Hydrochloride per litre, and made up to a litre will be more similar to R09 but with a lower sulphite content and no anti foggants. Of course it works as is it's such a simple develop.

    Ian
    Last edited by Ian Grant; 08-24-2009 at 03:23 PM. Click to view previous post history. Reason: typo

  5. #34
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    Quote Originally Posted by Photo Engineer View Post
    Patrick;

    I was giving you a possible answer. It might have oxidized to Potassium Sulfate which is much less soluable! Thats all.

    PE
    I have some of the concentrated K2SO3 45% solution coming. I think that will work just fine, and probably keep better.
    Gadget Gainer

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    Ian;

    I don't find Bill speculating in the book at all. He may have in a post, but I have not looked that up. In the book it is rather straightforward regarding Rodinal and the formula is quite reasonable.

    PE

  7. #36
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    Quote Originally Posted by Photo Engineer View Post
    Ian;
    I don't find Bill speculating in the book at all. He may have in a post, but I have not looked that up. In the book it is rather straightforward regarding Rodinal and the formula is quite reasonable.
    PE
    Page 59 of the FDC 3rd paragraph of the block titled Agfa Rodinal - Bill Troop states that "Potassium Bromide has also been added, which would not be necessary if p-Aminophenol was the sole developing agent"

    That's speculation

    I have the same formula as Bill publishes in the FDC in many books, and Dr Momme Andresen published it in an Agfa publication himself, it's often listed as a Paramidophenol single solution developer, which is Agfa's original name for p-Aminophenol.

    No-one doubts the formula is close to Rodinal, but no book I have other than the FDC/DCB states it's the original Rodinal, in fact none even use the word Rodinal.

    J.Desalme & others state that Rodinal type developers use the free base rather than the hydrochloride. Desalme is likely to have been well informed, he was researching similar developing agents to Andresen including phenylene diamines, aminophenols, and disclosed Pyramidol as a developing agent in 1912. (His first research papers are from the1890's).

    A 1912 research paper from Cornell University, quotes from work done by Sheppard and Mees (1907 so pre-Kodak) indicating that p-Aminophenol developers aren't suppressed by high levels of Bromide. So there's no reason what so ever why a high level of Bromide can't be present in modern Rodinal purely to suppress fog caused by the higher level of Hydroxide.

    Ian

  8. #37
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    Ian;

    Thanks, I was looking on the wrong page. Found it. I can agree with what you say, to an extent. You see, you are right also about p-Aminophenol developers not being supressed by high levels of Bromide (AFAIK) but OTOH, this is an interaction with all ingredients and hydroxide is quite similar in all versions and so Bromide would have no extra effect as a function of hydroxide in any version of Rodinal.

    Therefore, there must be a reason for the high level of Bromide. Something else is going on if Bromide does not act as an effective antifoggant with Hydroxide. I would like to suggest that it might be moderating edge effects which began to become prominent as film emulsions evolved. Think about it.

    PE

  9. #38
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    Ron, I think what Sheppard & Mees found was that Bromide works well as an anti-foggant in p-Aminophenol devlopers, but with some developers/developing agents at a higher level the Bromide suppresses overall development, Metol & MQ developers are prone to this.

    Anyway Rodinal has been using a combination of Bromide and an organic anti-foggant for over 64 years, so this seems to dispel the speculative statement. How much they might have raised it by when the reformulated is less important.

    People who prefer the older Calbe R09 version claim it's cleaner working, it's probable the extra hydroxide in Rodinal may lead to a higher base fog, but in all honesty Agfa Rodinal is a superb developer and with Tmax 100 or Agfapan 100 delivers cleaner sharper negatives than ID-11/D76 IMO. It was my main developer for personal work 35mm to LF for about 19n years.

    Was Kodinol, the Kodak p-Aminophenol concentrated developer, ever sold in the US. There's nothing on the internet at all, but it's listed in my Kodak UK 40's & 50's books.

    Ian

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    Kodinol does not appear in any of my books back to 1941. I don't remember ever having heard of a PAP developer either when I started developing pictures in the 40s or when at Kodak. I would have to assume that it was not sold in the US.

    If Rodinal works well with no bromide then that should tell us something about fogging and about development in this developer at this pH with this deveoping agent. Something slightly different is going on than in average developers and I think I am beginning to understand it.

    My train of thought does suggest that there are some variants that can be designed with some superior trait or other.

    PE

  11. #40
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    Just as a matter of p-aminophenol interest, I have a U. S. War Department Technical Manual of Basic Photography dated July 1, 1941 that lists a Tropical Developer:

    Water (at 125 F)..............96 ounces.
    Para-aminophenol hydrochloride.....400 grains.
    Sodium sulfite (des.)....................6 ounces, 200 grains.
    Sodium carbonate (des.)...............6 ounces, 200 grains.
    Water to make 1 gallon.

    This translates to 7, 50 and 50 grams per liter. It was to be used full strength. Adding the sulfite should result in precipitation of the p-aminophenol base, as it does when making Rodinal, and I suppose a paraminophenolate is formed to make it soluble as the carbonate is added.
    Gadget Gainer

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