Homemade rodinal

Discussion in 'B&W: Film, Paper, Chemistry' started by analog what is that?, Nov 27, 2011.

  1. analog what is that?

    analog what is that? Member

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    A discussion homemade rodinal based on Tylenol tablets on the flickr forum for alternative developers, Caffenol.
    A look at how developer activity takes time to reach it's full after initial mixing. This is something anyone can do. :smile:

    Just go to flickr.com, find discussions.
    Search for discussion no. 72157628011740415
     
  2. chioque

    chioque Subscriber

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    IMHO it's better if you just post the link, much easier for people to follow for those not familiar with flickr.
     
  3. Trask

    Trask Subscriber

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  4. analog what is that?

    analog what is that? Member

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    Sorry, just entered and those in power have limiteed whats allowed, links are disallowed, probably a good idea, given todays spam climate......
     
  5. daveandiputra

    daveandiputra Member

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    Sooo it's basically Parodinal.
     
  6. MattKing

    MattKing Subscriber

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    You can actually copy the linking information - you just can't make it an active link.

    Welcome to APUG.
     
  7. analog what is that?

    analog what is that? Member

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    Yes basically, what interested me was if the info "let it stand for 72 hours" really was needed, high hopes and bragging aside, it was! :smile:
     
  8. polyglot

    polyglot Member

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    It's Parodinal and the original recipe calls for 72+ hours of waiting time. Activity increases for the whole of the first week, after which it pretty much levels off at the appropriate strength.

    The time taken is for the NaOH to hydrolyse the paracetamol, you definitely have to wait for the reaction.
     
  9. analog what is that?

    analog what is that? Member

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    Yes and I just documented what happens during those 72 hours wait, to satisfy my own curiosity.......
     
  10. Alan Johnson

    Alan Johnson Subscriber

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    Another snippet of information:
    The Parodinal formula calls for 20g sodium hydroxide but the chemical equation for the hydrolysis only requires 8g.
    I tried using only 8g sodium hydroxide (along with the sulfite) to hydrolyse the paracetamol/tylenol.
    After 72 hours a 1:50 solution produced very thin negatives and after 10 days still thin negatives.
    So it appears that an excess of sodium hydroxide >8g is needed to complete the reaction in a reasonable time.
     
  11. el wacho

    el wacho Member

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    how much more?

    Would an extra two grams be enough Alan?
     
  12. Alan Johnson

    Alan Johnson Subscriber

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    I don't know.
    I did not pursue it as the formula for PaRodinal works well enough.
    It would really only be of interest to someone needing to synthesize their own p-aminophenol.
    I have made a solvent developer by adding sulfite and boric acid to the sodium aminophenolate made by hydrolysis of paracetamol.It worked like D-76 but since it took twice as long to develop film at the same pH it is really only of interest to those unable to get phenidone or metol.I did not pursue this either.
     
  13. Tronds

    Tronds Member

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    Don't fiddle with the parodinal recipe. It works and it works well.
    Changing the recipe will change it's performance and all data will be void.

    Make Parodinal as the recipe says.

    You can then take some of it and make a great working TCB developer.

    I have done it and my version will keep for many weeks as a working solution.
    Development time about 10 minutes for 100ISO B&W films.

    More data and pictures on http://ascorbate-developers.blogspot.com in a day or so.
     
  14. Alan Johnson

    Alan Johnson Subscriber

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    3 developing agents in "Fenomenal"- hmm.
    Try leaving out the phenidone to see if the p-aminophenol is actually doing any developing.
    It looks like Gainer's PC Borax with added sulfite and bromide buffered with sodium hydroxide.
     
  15. analog what is that?

    analog what is that? Member

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    Did you record the pH for only 8g of NaOH?
    I should think we need NaOH in excess to make an organic reaction run smoothly, this is reflected in the bath-time, 72 hours is UNUSUAL to say the least..... And it is rare for organic reactions to run much over 50% inless they are strongly cohersed.

    Also we need a good strong pH in the DILUTED developer to keep it vigorous, I think.

    i did record pH all along the test-run mentioned here.
     
  16. analog what is that?

    analog what is that? Member

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    Alan you shold try it with ascorbic acid as well, I've seen the results and am convinced.
    You get better grain and high contrast.

    I'm setting up a testrun, comparing a mix with original Agfa Rodinal with Parodinal, to see if theres a difference.
     
  17. Tronds

    Tronds Member

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    Been there, done that.
    I have made a TCB developer with 4 times as much parodinal and 3 times as much ascorbic acid.
    Borax was used as alkali so the pH was about the same, 9.15.
    Development time for 100 ISO B&W film was 10 minutes @ 20C.
    Also a good developer, but still lacking some qualities.

    The Parodinal is actually 1:400 in the working solution.
    This dilution of parodinal used alone will give development times of about 15 to 20 minutes.

    Both phenidone and p-aminophenol forms superadditive pairs with ascorbic acid. Leaving out one ingredient will make a huge impact on the activity level of the developer.

    A working solution with a pH of 9.1 doesnt look like it's buffered with sodium hydroxide.
    Borax is the alkali that is controlling the pH in this developer. The ascorbic acid is close to neutralizing the effect of the sodium hydroxide from the parodinal.

    Leaving the phenidone makes a big difference. Leaving out the ascorbic acid does also make a big difference. The pH will be a bit higher and grains will increase.
    Leaving out the parodinal increases development time and results in less density in highlights.

    Be my guest and do some tests yourself. Mix the developer in three different versions where you leave out one ingredient in each.

    Please do and please report back the results from the testing.
     
    Last edited by a moderator: Nov 28, 2011
  18. Gerald C Koch

    Gerald C Koch Member

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    The amide hydrolysis of acetominophen is more effective in acidic solution than basic solution. The excess sodium hydroxide may be needed to effect the hydrolysis in a reasonable time. Typically a substituted amide such as acetominophen would be refluxed with dilute acid such as sulfuric acid then the solution would be neutralized to yield p-aminophenol.
     
  19. Alan Johnson

    Alan Johnson Subscriber

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    This seems well out of line with the massive development chart which typically gives a time of 20min for Rodinal 1:100 ,and that at pH ~12.
     
  20. analog what is that?

    analog what is that? Member

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    I found when testing Caffenol (no ascorbic acid, just coffe, that I got no developing action or very low developing action in the concentration I had. When I added rodinal to that mix at 1:200 I got negatives, but needed ca 30 - 35 minutes time.....

    I'd say that morte than 95% of the activity of that mix was rodinal alone, and that is the time I would try for pure rodinal at 1:200
     
  21. Tronds

    Tronds Member

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    You are probably right. I didn't check since it isn't realy of any interest how many minutes it will take. What is of interest is that the rodinal part doesn't do the development alone.

    I haven't seen any numbers for 1:400 dilution, so I think we can agree that it will take a looooong time to develop a film in that.
     
  22. Alan Johnson

    Alan Johnson Subscriber

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  23. Tronds

    Tronds Member

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    You are right! A typo. In my notes it reads 8g.

    Corrected just now.
    Thanks for spotting the error.

    Trond.