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  1. #21

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    Hi Martin,

    Paracetamol: about 100 g I suppose (that will make 1.3 liters by quick calc)

    Panadonal produces acetate instead of chloride. Paracetamol is a 4-aminophenol with an acetyl functional group attached - when that is removed by the hydroxide it produces an acetate. That reaction is slowish, and the reason why it has to ripen for two or three days. Glycin and metol are also related molecules, and I suspect they may also be transformed into Rodinal.

    Don't filter, just put in everything and let it simmer. If any crystals form, it may be aminophenol in equilibrium with aminophenolate, which is part of the buffering necessary to preserve the developer. Let things settle, and use a dropper to extract the developer. If one uses capsules they form a fine muck that is probably binder, but using pure paracetamol that shouldn't happen, in theory at least.

    You do not need KBr for this developer, I think initially it was added because without it the older film emulsions tend to fog heavily, just as our experience with RPX400. It may help if you add KBr specifically for such emulsions, but I haven't tested and don't know for sure. In that case, add it to the diluted developer, not to the concentrate. I have plenty of KBr, will send you some. It is used in Caffenol C-L too, so useful to have around, and I would say consider using it for stand development in general if you get streaky developing.

    Will check your calcs tonight, and will PM you my calculation sheets.

    Jaco
    Last edited by dorff; 08-30-2012 at 06:51 AM. Click to view previous post history.

  2. #22
    hmzimelka's Avatar
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    Fantastic, thank you.

    I just got a quote from BMScientific. Their prices are very high.
    R89/500gr Sodium Sulphite
    R39/500gr KOH

    The suppliers I use sell the Sodium Sulphite for R13/kg and the KOH for R23/kg. Anyways.

    Looking forward to your PM.
    I'll send you the paracetamol next week, when I have purchased more paracetamol and hopefully also have my own car back...

  3. #23
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    I developed a roll of film yesterday with monday's Parodinal batch 27082012-02 (The clear one)
    At the time of opening, it was still clear, but more yellow in colour. After developing, the first crystals started appearing, and by this morning the colour is slightly pink-ish.

    Here is another scan comparing it to the Rodinal R09 One-Shot I have:
    The full res version is available for download HERE


    With thanks to Jaco, I will be changing the formula and will be using KOH instead of NOH. Also, I will give a go at using a Potassium Metabisulphite based formula, just to feed my curiosity. I will continue with the scanned comparisons once those solutions are ready for use! Hopefully by monday I will have made these new batches!
    Last edited by hmzimelka; 08-31-2012 at 03:07 AM. Click to view previous post history.

  4. #24
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    Quote Originally Posted by dorff View Post
    Hi Martin,

    Are you planning on ordering from BM Scientific? I got some of my chemicals from them, including enough KOH to share. You can also try Minema - they are generally cheaper and will have stock, but don't buy as yet. Rather PM me your postal address and I'll send you some KOH, as well as another surprise or two. My stocks are all in 500 g + quantities, and for things like developers that is usually more than one needs for a long time. Yes, for certain I would like some paracetamol, but I will trade you for it.

    About Parodinal: I would advise against metabisulphite and/or carbonates as they affect the pH and you would then have to tweak your total balance to get things right, and it is not really necessary in the first place. You really only need three things: hydroxide, sulphite and paracetamol. If the hydroxide is potassium hydroxide, the solubility of sulphite is improved because of the "common ion effect", where fewer sodium ions compete to stay in solution. Potassium salts are as a general rule more soluble than sodium salts on a molar (and hence also mass) basis, and this is why if you use NaOH you will battle to get the sodium sulphite dissolved, but if you use KOH all eventually dissolves. You can use potassium sulphite with sodium hydroxide too, based on the correct molar (not mass) quantities. I'd be happy to do the calculations for you if you do not know how. Basically you divide the mass by the molar mass of the specified chemical, and multiply by the molar mass of the one you substitute. So for KOH substituting for NaOH the correction is 56.1/40.0 = 1.40. The same principle will apply to sulphite but the factor would be different (1.26) etc. I reverse-calculated the Panadonal-K formula against two other formulas - the pre-war Rodinal formula (which differs in containing EDTA and KBr) and the formula for Rodinal published in The Darkroom Cookbook. Those two formulas have the same 4-aminophenol content (within 1 %), and the Zorkikat formula is about 80 % of that. I think that is because ZorkiKat used only sodium chemistry and couldn't get everything into solution as is supposed to be the case. If you filter the Zorkikat formula, you will be in trouble, because the excess sulphite is necessary to protect the aminophenol from oxidation. The TDC and original formulas both employ potassium as well as sodium but in different ways. However, the end product has more or less the same composition in either case, and my adaptation matches that fairly well. The difference between various formulas lies in the byproduct which is usually derived from the way in which the aminophenol is introduced. In the case of TDC it is chloride, in the Parodinal formulas it is acetate, and in metonal it will be something like sulphate. I think at the concentrations after dilution 1:50 these byproducts do not affect the developing much, but I would appreciate if someone with more insight can comment. NaCl does affect some developers, but typically at higher concentrations than what one finds in Rodinal.

    Regards,
    Jaco
    My K-Parodinal mixed according to Jaco's instructions has cured and I shot a sheet today in strong [15 EV] sunlight. There is a large difference in shadow illumination at this time of the year and normally shooting anything at midday is problematic. I used exactly the same dilution and times for Rodinal. The K-Parodinal was slightly more contrasty with very similar shadow density. I metered with an incident meter as a single reading back towards the camera at 160 iso [Foma 200] I measured the negatives with my densitometer and the DR for both Rodinal and K-Parodinal sits at about 1.08 which is just right for a grade 2 print. 1.07 Rodinal 1.08 for K-Parodinal. The slight difference is irrelevant. I would say more due to me than the developers.

    Is it the same as Rodinal? I have a test set up I use regularly and I ended up only shooting the one neg but have many Rodinal negatives to compare characteristics shot under the same light. I would have to say the mid and upper mid tones on the K-Parodinal neg are superior. Very smooth handling of highlights also. The blacks are clean and the whites clear and creamy. I think the K-Parodinal negs have the edge in sharpness and definition. Processed in a Jobo rotary system the sharpness and acutance is just wonderful. Most people are making the Parodinal with Sodium Hydroxide but considering I have enough Potassium Hydroxide to leave for any relatives I have I opted for KOH as that is also used for Rodinal.

    Following exactly Jaco's instructions and dilutions based on the 200ml not 250ml final volume gave absolutely remarkable results.

    My verdict -- K-Parodinal certainly takes the pain out of film development and I really feel it has enormous potential. I would certainly not loose sleep now if Rodinal suddenly disappeared.
    Steve

  5. #25
    hmzimelka's Avatar
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    Thanks, Steve. Good info I must also agree that Jaco's formula is working gloriously.

    So, to get everything up to speed...

    I've made a few batches of Jaco's formula, and am very pleased with the results. There has consequently been a lot of email correspondence since.

    The current Parodinal family:
    Click image for larger version. 

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    On the left (they yellow/amber colour solutions) are my early batches I made when I started this thread.
    Batches 25082012-01 (the small bottle), and batches 27082012-01 and 02

    In the middle, the two 250ml blue capped bottles, are batches I made with Jaco's recipe. Batches 03092012 and 07092012.
    Batch 03092012 was made with 10% extra KOH, since the technical grade KOH had a minimum ASSAY of 89,5%.
    After making this, Jaco assured me that the 10% compensation was too much, and that his recipe would have sufficient KOH required.
    This lead me to make batch 07092012, which was made as instructed. I still haven't tested this batch
    Of the two, I have only developed film with batch 03092012, which worked as advertised. (See comparison bellow)
    Click image for larger version. 

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    The large bottle on the right is Batch 11092012, which was made with KOH + K2S2O5. This stuff needs to cure for two more days before I can test it.

    All in all, I'm incredibly happy about the very clean and clear end product. So many thanks Jaco!

    Some real world images instead of boring test shots:










  6. #26

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    Quote Originally Posted by dorff View Post
    Glycin and metol are also related molecules, and I suspect they may also be transformed into Rodinal.
    Add to this list hydroquinone. Phenols easily form phenolates with strong alkalies like sodium hydroxide. During WW! it was impossible to obtain Rodinal. An American photographer created a delevoper concentrate which acted like Rodinal. It contained metol and hydroquinone and was sold as Kalogen. You can find his formula and advertisement on the Library of Congress website. I have used a modified version of this developer for film and prints for over 10 years. Like Rodinal it lasts for years.
    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

  7. #27
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    I tried to locate pure paracetamol but had no luck so my version is based on 30 crushed 500mg tablets. I have a very nice granite mortar and pestle and ground the tablets to an extremely fine state.
    My developer is not clear like your version, milky in fact, but there is no detrimental action on the negative because of the tablet filler.
    A hard compact layer of I presume filler is forming on the bottom of the bottle. This layer is about 1 mm and may have some crystals as well. Due to the cloudiness of the developer I cannot really tell for certain.
    I use a 10 ml glass pipette to measure my developer so eventually when I get too close to this filler layer I will dump what is left and make a new batch.
    Based on my initial results I'm not concerned about using the tablets and won't stress about the cloudiness of the developer.
    I have a batch curing at present that I made 2 days ago with Sodium Metabisulphite and KOH. I will test a sheet today or tomorrow and report back. If it is successful I will post the quantities I used.

    Thanks again to Jaco for helping with the quantities needed. I'm not a chemist. A careful tinkerer but definitely not a chemist.
    Steve

  8. #28

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    Quote Originally Posted by chiller View Post
    A hard compact layer of I presume filler is forming on the bottom of the bottle.
    The technical word you want is excipient. Since they are usually insoluble in water you don't have to grind the tablets very much. If you just break the tablets up a bit you will probably avoid the cloudiness problem.
    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. #29

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    Quote Originally Posted by dorff View Post
    Don't filter, just put in everything and let it simmer.
    Paraminophenol is very sensitive to oxidation and so it is best not to use heat. Be patient and the hydroxide will split off the acetyl group.

    You can prepare paraminophenol by refluxing the tablets with dilute hydrochlioric acid. You will need a suitably sized Erlenmeyer flask, a one-hole rubber stopper and a two foot length of glass tubing. Use 1N hydrochloric acid and heat for about an hour. The tubing acts as a primitive condenser. The mixture does not have to boil. Since some hydrochloric and acetic acids will be released this is best done in the open air. Allow the mixture to cool and then filter it. The free base paraminophenol can be precipitated with either sodium carbonate or bicarbonate. Do the neutralization gradually to prevent foaming. To prevent oxidation add a pinch of sodium sulfite to the solution before adding the carbonate. The free base will form as buff colored greasy scales. It can be recrystallized by dissolving in hot water to which a small amount of sodium sulfite is added and allowing the solution to cool.
    Last edited by Gerald C Koch; 09-12-2012 at 10:58 PM. Click to view previous post history.
    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

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