Rodinal (EZ , Gainer Formula) Troubleshooting

Discussion in 'B&W: Film, Paper, Chemistry' started by chakra, Jun 12, 2008.

  1. chakra

    chakra Member

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    I gave making Patrick Gainer's EZ Rodinal a try after reading the forum posts here. It seemed more straightforward than the Anchell and Troop book version.

    The EZ Rodinal formula is
    To 400 ml water, add: 85 g anhydrous sodium sulfite. 40 g p-aminophenol base. Stir well. Add 13.8 g sodium hydroxide or 19.2 g potassium hydroxide. Add water to make 500 ml.

    To a brown bottle with 400ml deionized water I added the sodium sulfite first and the p-aminophenol next, while constantly stirring with a magnetic stirbar. Not much seemed to dissolve even after 30minutes and heating to about 60 degrees. So I put in the KOH and the solution cleared quite a bit. The magnetic stirrer has went for a few hours but the solution was still quite cloudy and a lot of undissolved material is present. I would say about 2-3 tablespoons full of crystals. And it doesn't settle very readily.

    Is this normal? I thought that only a few crystals were supposed to remain. Also, does this mean that I should titrate in more base until a tiny amount of precipitate is left? If so, what is the target pH of Rodinal? I would appreciate advice from people who've tried this formula out before.

    Thanks,
    Santanu
     
    Last edited by a moderator: Jun 12, 2008
  2. gainer

    gainer Subscriber

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    The sulfite should dissolve readily. The p-aminophenol should not. If it did, it would be a sign that you had used p-aminophenol.HCl. This can be done, but will require different proportions. The hydroxide might be partly K2CO3 due to exposure to atmosphere.

    The hydroxide converts p-aminophenol base to the potassium salt which is water soluble.

    After I read your post, I retreated to my dungeon and made a batch of EZ-Rodinal. I had less than a teaspoon of sediment after stirring a few minutes with a soupspoon (my recently discovered automatic stirring machine). I tested it on HP5+ at 1+25 dilution according to instructions on an old Rodinal container, with proper results.

    If through some accident you had used the p-aminophenol.HCl, the proper cure would be to double the amount of KOH. If the KOH is weak for one reason or another, the proper cure is again more KOH, but not so easilly determined. Perhaps the reason for the titration in older recipes was the uncertainty of purity of either or both p-aminophenol and KOH. You could not go wrong by adding more KOH to see if more of the sediment dissolves. It runs in my mind that a saturated solution of KOH will hold very little K2CO3, and will have a concentration that depends on temperature. If you make such a solution at a temperature higher than you are likely to have while working in your darkroom, and make sure it has an excess, you can use a table from the CRC Handbook of Physics and Chemistry to calculate how many ml of this solution will contain 19.2 grams of KOH at the current darkroom temperature.

    You could try filtering out the precipitate and testing the clear liquid as if it were Rodinal.
     
  3. chakra

    chakra Member

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    Hi Pat,

    Thanks so much for your reply and for testing the formula out yourself.
    I bought the p-aminophenol and sodium sulfite reagents brand new from PhotoFormulary. The KOH was from a nearly full but old bottle in a research lab where I work.

    I started the automatic stirrer with 400mls of water and dunked in the sulfite followed immediately by the p-aminophenol. So I am guessing that the sulfite went into solution but but the white stuff that simply would not dissolve was mostly p-aminophenol. I checked to see that the p-aminophenol bottle does not say HCL on it.

    After adding the KOH (added pellets directly to the mix) things cleared but still had way too much sediment in it. So I added about 6 more grams of KOH in 2 gram steps. After the last two grams things suddenly cleared, the color went a bit pinkish and left only a tiny amount of crystals in it. I was worried about if I had added too much KOH. So I checked the pH and found it was about 12.5 (using both pH paper and a pH meter). This seemed high , but googling didn't turn up any references for rodinal's target pH which seemed a good way for getting some kind of standard.

    I'll try this again tomorrow. A couple more questions
    1. Does the order of adding the reagents make a difference?
    2. I have old but nearly full bottles of both NaOH and KOH. Is there a reason to prefer one over the other?
    3. What final pH should I be shooting for?

    Thanks,
    Santanu
     
  4. gainer

    gainer Subscriber

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    I'll check to see what pH I got. It will be pretty high, I'm sure. The sodium paraminophenolate is a salt of a strong bas and (I guess) a weak acid if that rule says anything about this situation. I did measure the pH of a 1:25 working solution, but forgot to write it down.
     
  5. gainer

    gainer Subscriber

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    I read 11.9 in the batch of stock I just made. As I said, it behaves just as I would expect Rodinal to behave. I don't think you need to worry. Just try developing a test strip. The diffrence between 11.9 and 12.5 is not much at that level.

    I think from the standpoint of protecting the p-aminophenol, it is best to ddissolve the sulfite first, then the p-aminophenol, then the KOH. I think K salts were easier to get or make for the Germans at the time of Rodinal's inception. It was interesting to me that Hurter & Driffield mentioned rodinal, with the lower case, as a developing agent. I suspect that was potassium paraminophenolate. If that is available, it would simplify things for us, would it not?
     
  6. john_s

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    If you want to read more on the subject of Rodinal, you might be interested in this post on rec.photo.darkroom, in which Michael Gudziniwicz discusses someone else's "home brew" made with p-aminiphenol:

    http://groups.google.com/group/rec.photo.darkroom/msg/c72091a611cfaf87

    You can see the whole thread by clicking on the link of the title , i.e. "My Home Brew."

    Unfortunately rec.photo.darkroom isn't nearly as good as it used to be, but there are some gems there.
     
  7. chakra

    chakra Member

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    OK. So I redid the preparation in graduated 50ml plastic tubes with both KOH and NaOH.

    To 40ml deionized water I added 8.5 gram sodium sulfite. Capped the tube and inverted until it dissolved. To this I then added 4g p-aminophenol base. That led to some kind of whitish colloidal precipitate which would not dissolve further. Next I started titrating with a ~20 molar solution of KOH. There was a very clear relation between amount of base added and how much precipitate went into solution. I titrated until there was only a pinch of precipitate left at the bottom. I had to add about 5 grams equivalent of KOH solution and the pH was 13.1.

    I redid this with NaOH and it was MUCH harder to get the solution to clear. I have the tube sitting with precipitate upto about the 10ml mark and a pH of 12.8. If it doesn't clear by tomorrow I'll bring the pH upto about 13.1 so I can compare the two solutions.

    The 5 gram number is almost 3 times the amount should need to add, and it makes me wonder if the bottle was mispackaged or if age of the p-aminophenol makes a difference. And I am still a bit worried that my solution clears at a higher pH.
    I'll run a comparison with Tri-X in the coming week and report back.

    I am also realizing that I have almost no understanding of the underlying chemistry.
    Could you recommend a few photographic chemistry texts or manuscripts?

    Thanks,
    Santanu
     
  8. gainer

    gainer Subscriber

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    Have you read the post by Gudzinowicz in re.photo.darkroom? It is quite enlightening.

    Test the water solubility of your p-aminophenol. If it is in fact the base, it should not be very soluble. The hydrochloride is more soluble than Metol.

    I don't think that is the problem, though. Of course, our pH meters may not be calibrated alike, but the pH of my final solution with just a little precipitate reads less than 12.

    Traditionally, the preparation of Rodinal begins with p-aminophenol.HCl in solution. Adding potassium metabisulfite does not cause it to precipitate. The first addition of hydroxide, either Na or K, removes HCl from the tail, which makes the flocculent precipitate. As more hydroxide is added, the potassium or sodium aminophenolate salt is formed, which is the final developing agent, and is quite soluble in water. If you have pure ingredients, the amount of each one required to convert all the p-aminophenol.HCl to a solution of the aminophenolate salt and NaCl or KCl can be calculated. The shelf life of the Rodinal stock is much extended if some of the p-aminophenol base is left undissolved. I do not know why, but apparently Gudzinowicz does. The amount of hydroxide required to remove the HCl from the hydrochloride is, in molecular weights, the same as the amount required to make the aminophenolate, so using the p-aminophenol base in place of the hydrochloride will require only half as much hydroxide. Last time I bought any, a pound of the base cost the same as a pound of the hydrochloride, so I saved money two ways.

    Obviously, impurities anywhere along the line can bolix up the calculations. The impurities are not likely to affect the performance of the developer if the traditional titration is done at the end. You will wind up with a solution of sodium or potassium paraminophenolate and a sulfite in water with some precipitate which should be kept with the stock. You may not know the exact concentration of the stock if part of the p-aminophenol was the base and part was the hydrochloride, but calculating the concentration from the nominal weight of p-aminophenol and the final volume will be close enough for government work.

    What bothers me most is the difference in pH between yours and mine. That could, of course, be due to differences in calibration between meters, were it not for the test strips.
     
  9. MikeSeb

    MikeSeb Member

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    I'm not sure whether to admire or pity you Rodinal-junkies....jeesh, mixing a developer ought to be Betty Crocker, not Los Alamos. I think separating uranium must be easier than mixing this stuff.

    :smile:
     
  10. chakra

    chakra Member

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    I was worried about impurities. So I checked the KOH/NaOH bottles. The KOH says > 87% (kinda low!) but the NaOH says >99.7% and both are behaving somewhat similarly.
    I prefer the formula you posted both for reasons of simplicity and economy but I need to sort the pH thing out. I'll see if I can calculate expected pH theoretically. Something that just crossed my mind is that I should also stick the pH meter into a couple of bottles of commercial Rodinal that I have.

    But more fun will be to actually test the developer on film and compare results. My worry (other than lack of understanding on my part) is that higher pH may lead to higher grain.
     
  11. chakra

    chakra Member

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    It's FUN!

    Hey Mike,
    Mixing it yourself is actually quite fun :D and easy. And you get the added advantage of consistency ... at least given your own set of reagents.
    And it's about 1/5 th the cost of buying it commercially!
    Did I mention fun ....:D:D:D:D

    -Santanu Chakraborty
    http://www.santanuchakraborty.com
     
  12. gainer

    gainer Subscriber

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    There is a way to add ascorbate to Rodinal working solution that seems to give somewhat finer grain without disturbing its other characteristics. This is described in www.unblinkingeye.com somewhere. Briefly, mix 1 teaspoon ascorbic acid powder with 1/2 teaspoon sodium bicarbonate in a small amount of water. When effervescence ceases, add 20 ml Rodinal concentrate and water to 1 liter. Treat the mixture as 1:25 Rodinal. This essentially forms a sodium paraminophenolate-ascorbate developer that you can play with while you're having phun.
     
  13. chakra

    chakra Member

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    I have a tendency to get carried away having phun instead of taking photographs. I'll out the ascorbate idea but after I've tested the EZ KOHnal I made.
    One question, why not just add Sodium Ascorbate? Some health food stores seem to have it.
     
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  15. gainer

    gainer Subscriber

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    No reason except it doesn't seem to keep as well as the acid, and some recipes call for the acid. If you decide some day to play with stock solutions in glycol or TEA, the ascorbate will not dissolve but the acid will. I find it more convenient to have a container of ascorbic acid and one of baking soda than one of ascorbic acid and one of sodium ascorbate. Besides, when things don't go right, the baking soda helps the ensuing gastric disturbance, so I need the baking soda anyway.:tongue:
     
  16. chakra

    chakra Member

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    Hi Pat,
    I let the original batch of KOHnal sit for a couple of days. When I came back the color was darker and the pinch of precipitate was gone. This was in a light-tight and air-tight 50ml falcon tube.
    So I thought, I'll remake a 50ml batch and see what happens. If I follow the amounts from your formula and let the solution sit for a day, I get a 50ml solution that is the color of Agfa Rodinal (light pink in the beginning, turns darker after a day) and has a whitish pink precipitate of about 4 ml volume at the bottom. More importantly, the pH is at 11.9 which is exactly what you get. I brought the pH upto 12.
    I've developed a roll of Tri-X in commercial Rodinal which is drying now and will develop a strip of 10 frames of Tri-X from the same batch to see how it looks. We should have a comparison soon.
    Thanks,
    -Santanu
    http://www.santanuchakraborty.com
     
  17. chakra

    chakra Member

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  18. gainer

    gainer Subscriber

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    You're quite welcome.
     
  19. Relayer

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    Hello

    I was found two different formula for EZ-Rodinal

    1st early version found here: http://www.apug.org/forums/forum37/21181-rodinal-substitutes-4.html

    Start with 700 ml water at room temperature.
    Add 170 grams of anhydrous sodium sulfite, 14 grams sodium hydroxide, and stir till dissolved. Warming it a little won't hurt. Add 40 grams p-aminophenol (not the hydrochloride). It will not all dissolve. Add water to make 1 liter. When you transfer from the mixing vesel to storage, do not filter out the sediment. Use it like AGFA Rodinal.

    2nd (latest) version from EZ-Rodinal article http://www.apug.org/forums/forum223/34163-ez-rodinal.html

    To 400 ml water, add:
    85 g anhydrous sodium sulfite.
    40 g p-aminophenol base.
    Stir well. Add
    13.8 g sodium hydroxide or 19.2 g potassium hydroxide.
    Add water to make 500 ml.

    rewrite this formulas for 1l concentrate:

    1st version
    Sodium sulfite 170g
    p-Aminophenol base 40g
    Sodium hydroxide 14g
    Water 1l

    2nd version
    Sodium sulfite 170g
    p-Aminophenol base 80g
    Sodium hydroxide 27.6g
    Water 1l

    easy to see that 2nd version have twice amount of p-Aminophenol. Compared to known Rodinal formula from http://www.digitaltruth.com/data/rodinal.php

    p-Aminophenol Hydrochloride 50 g
    Potassium Metabisulfite 150 g
    Sodium Hydroxide 100 g
    Cold water to make 1L

    while we mix all ingredient reaction describes next formulas

    K2S2O5 + 2NaOH = K2SO3 + Na2SO3 + H2O
    C6H4OHNH2.HCl + 2NaOH = C6H4ONaNH2 + NaCl + 2H2O

    MW(C6H4OHNH2.HCl)=145.59, so formula contains 50/145.59=0.343M of p-Aminophenol Hydrochloride. For PAP base MW(C6H4OHNH2)=109.13. and amount of base will be 109.13*0.343M=37.48g. This is near the 50g in 1st version of EZ-Rodinal.
    Amount of K2SO3+Na2SO3 is 1.35M. We need 1.35M*MW(Na2SO3)=1.35M*126.04=170g of Sodium sulfite. This is also same as in 1st version.

    So my question - is the 2nd version of EZ-Rodinal correct?
     
  20. dorff

    dorff Member

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    Hi Chakra,

    I won't go into the details of the rest of the discussion, but wanted to make two quick comments.

    1) I made the A&T version, but only after I had decided to dissolve the p-Aminophenol in hydrochloric acid to be sure I had the hydrochloride version. The rest went well, and the developer worked exactly as it should. It seems laborious, but given the amount of developer it makes for fairly little trouble and money, it is well worth it.

    2) I have since settled on parodinal, which works exactly the same and is a lot cheaper and easier to make still. The reason it is cheaper is because paracetamol is available in bulk quantity for next to nothing via pharma suppliers, while 4-aminophenol is usually special order as an AR grade lab chemical. If you haven't done parodinal before, I must urge you to give it a go and decide for yourself. For a very straightforward, foolproof method, look up my thread with the attached excel calculation sheet. If it fails you, I'll make you a 1 litre bottle and keep it for you until you visit South Africa. It will still be good 20 years from now.
     
  21. Murray Kelly

    Murray Kelly Member

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    Dorff, a link please. Can't find it. TIA

    look up my thread with the attached excel calculation sheet

    Murray
     
  22. MattKing

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    I'll fill in for Dorff: http://www.apug.org/forums/forum37/110084-pa-rodinal-calculator.html (I expect)

    Just click on his name, go to his profile and click on the link for his most recent started threads.
     
  23. Relayer

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    parodinal is interesting other thing, but this thread related to EZ-Rodinal and my question in post #18 about differences between two version of EZR is still open.
     
  24. Ian Grant

    Ian Grant Subscriber

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    Rodinal cannot be made from p-amino phenol hydrochloride, it has to be the free base. This can be made first from the hydrochloride. So the formula you quote is wrong.

    Ian

     
  25. Relayer

    Relayer Member

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    Ian, check again ))

    C6H4OHNH2.HCl + NaOH = C6H4OHNH2 + NaCl + H2O
    C6H4OHNH2 + NaOH = C6H4ONaNH2 + H2O

    so my formula is correct

    C6H4OHNH2.HCl + 2NaOH = C6H4ONaNH2 + NaCl + 2H2O
     
  26. Ian Grant

    Ian Grant Subscriber

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    I repeat Rodinal does not contain p-aminophenol hydrochloride, so that's not the correct formula, it has no chloride of any form.

    If you start with the Hydrochloride first you precipitate and collect the free base. There's many descriptions on how to do this in books.

    Ian