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  1. #11

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    how much more?

    Would an extra two grams be enough Alan?

  2. #12

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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.

  3. #13

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    Quote Originally Posted by el wacho View Post
    Would an extra two grams be enough Alan?
    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.

  4. #14

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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.

  5. #15

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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.

  6. #16

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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.

  7. #17

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    Quote Originally Posted by Alan Johnson View Post
    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.
    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 Tronds; 11-28-2011 at 07:26 PM. Click to view previous post history.

  8. #18

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    Quote Originally Posted by Alan Johnson View Post
    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.
    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.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  9. #19

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    Quote Originally Posted by Tronds View Post

    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.
    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.

  10. #20

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    Quote Originally Posted by Alan Johnson View Post
    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.
    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

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