Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,907   Posts: 1,555,890   Online: 990
      
Page 1 of 3 123 LastLast
Results 1 to 10 of 26
  1. #1
    eclarke's Avatar
    Join Date
    Jun 2004
    Location
    New Berlin, Wi
    Shooter
    ULarge Format
    Posts
    1,957
    Images
    71

    Edwal Super 20..Chemistry Question

    A formula was posted here for Edwal Super 20. I'm going to make it as specified but have a question for the real chemists here. The formula calls for .2154 ml of pure sulfuric acid.. What can this tiny amount do in this developer?

  2. #2

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    3,944
    The sulfuric acid adjusts the pH because the formula calls for the free bases paraminophenol and paraphenylene diamine. It is best added as a 10% solution because of the small amount required would be hard to measure.

    However developers like this one are not needed with today's fine grain emulsions and the developer may actually cause dichroic fog with some. There was a reason why these developers fell out of favor.

    Paraphenylene diamine is poisonous and also causes severe allergic dermatitis. It is a cross sensitizer and may cause an allergy to develop toward other developing agents like Metol and the color developing agents. Use a dust mask and goggles when handling the solid and also nitrile gloves with the powder or its solutions. Paraphenylene diamine is a suspected carcinogen and mutagenic. Best to leave it alone. Developers like Xtol or Perceptol will produce grain almost as find as Super 20.
    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

  3. #3
    eclarke's Avatar
    Join Date
    Jun 2004
    Location
    New Berlin, Wi
    Shooter
    ULarge Format
    Posts
    1,957
    Images
    71
    Thanks, Gerald.
    I use around 2# of ppd a year and keep 10% solutions of all my acids, which I weigh for small quantities. Thanks for the cautions. I should have posted the info for the formula, it's interesting that it calls for the tiny amount of sulfuric acid, is specific about final pH and says to bomb it with hydroxide or acetic acid at the end to adjust the pH. I'm enclosing the recipe for you. Thanks for the feedback..Evan Clarke

    Hi Everybody,

    First a little background with a post I put up on Photo Net in 2003. It was as follows:

    Through the mid 60s to the 80s I used Edwal Super 20 exclusivly after trying virtually every developer then available, becase it gave an unequaled combination of very fine grain, high sharpness and (most of all) super compensation for the usually over-contrasty outdoor shots taken in the harsh Florida sun. I had originally become a fan of it because I had supplemented my TA stipend in graduate school by doing affordable 35mm portraiture and found it gave beautiful grain and tonality in that application.
    I am ready to do whatever it takes to duplicate the formula. Bud, the owner of the Photographers Formulary has talked to Bill Troop, co-author of the Film Developing Cookbook about the formula given there on page 67 and Mr. Troop has said that it is NOT, in fact, the correct one. The Film Developing Cookbook mentions in a note regarding the formula given that "incorrect" formulas have been published elsewhere. The Photographers Formulary suggested that if I could obtain one or more of these it (in conjunction with the Troop formula) it would give me a starting point to experiment with to try to home in on a working formula.
    If Super 20 can be duplicated , Bud would consider making it available to the B&W enthusiast community. I don't know how many of you have used Super 20 in the past, but rediscovering the formula would be a great service to the B&W community. It is a staining developer with many Pyro-like qualities, but with much finer grain, better acutance and much better compensating characteristics. If you can give me any leads I will be dilligent in following up and getting you the results of my attempts to replicate the formula. I have thousands of Super 20 negatives so I know exactly what results I am looking for! Thanks! Jay Ludvigh

    There was a good bit of discussion and speculation at that time, but nothing definitive regarding the exact formula. After conversations with Bill Troop and a bit of detective work I was able to track down Bob Schrader who was the production line supervisor for Edwal during the last years Super 20 was in production. He agreed to give me the formula, but asked that I not disclose it because he thought he might someday want to market it. I mixed it up using the facilities of the chemistry lab at the university where I'm adjunct faculty, because it is hard to get into solution an requires a heated magnetic stirer to get the job done. I compared it to my original negatives and while there were some differences because of the changes in more modern films it was clearly the same developer. I also was able to get an unopened, well stored bottle of Super 20 and compared it to my brewed version with modern films and found the results identical. So, what we have here is the real thing.

    The problem is that it is a pain to brew and I no longer have access to the chem lab due to a change in personel. I have been thinking that with the actual formula and expert input from savy APUG members, a more user friendly home brew method could be found. I have tried to contact Bob Schrader but have been unable to do so and since it has been over 9 years since he asked me to keep the formula to myself and nothing has happened in terms of him producing it I decided to make this post.

    Here is the exact formula which he provided me. According to the chemist who helped me make the first batch it has "archaic" chemical terms and units of measure, but here it is:

    To make 1 ltr

    1) Hot water 120-130F (distilled preferred) approx 28 oz.
    2) ParaAmino Phenol 2.62 gm
    3) Sulfuric Acid 66 degree baume (pure lab grade) .2154ml
    4) Sodium Sulfite 89.95gm
    5)Para Phenylene Diamine 9.59gm
    6) Glycin 4.797gm
    7) Water to 1ltr

    Desired ph-7.6
    Adjust with caustic soda (sodium hydroxide)/28% acetic acid
    do not add second chemical until first is dissolved

    The above is the word for word info he sent me on how to make Super 20. I sent him a heartfelt e mail of thanks and have not heard from him since. I deeply hope he is not still out there planning to go into production himself and am only posting this now to benifit other "film dinosaurs" like myself.

    If anyone with photochemistry expertiese out there can use the formula to figure out what Gradol was or how to brew Super 20 without having to use the sulfuric acid and ph adjustment process this could become a developer that a lot of people could use.

    Jay Ludvigh

  4. #4

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,857
    Evan - just be careful what you read about working characteristics. It's a highly solvent extra fine grain developer. High sharpness and compensation would be pretty much impossible. Also at this pH it is essentially a Glycin-PPD developer so there is likely some film speed penalty. All things considered, an odd choice for ULF

    Perhaps Gerald knows, but I wonder if p-Aminophenol is superadditive/regenerative with either Glycin or PPD. If not, it would be inactive at this pH.

    It's interesting that other than the substitution of 2.6g p-Aminophenol for 6g Metol (a significant change), the rest of the formula is virtually identical to Edwal 12 with some acid to lower the pH.

  5. #5
    eclarke's Avatar
    Join Date
    Jun 2004
    Location
    New Berlin, Wi
    Shooter
    ULarge Format
    Posts
    1,957
    Images
    71
    Quote Originally Posted by Michael R 1974 View Post
    Evan - just be careful what you read about working characteristics. It's a highly solvent extra fine grain developer. High sharpness and compensation would be pretty much impossible. Also at this pH it is essentially a Glycin-PPD developer so there is likely some film speed penalty. All things considered, an odd choice for ULF

    Perhaps Gerald knows, but I wonder if p-Aminophenol is superadditive/regenerative with either Glycin or PPD. If not, it would be inactive at this pH.

    It's interesting that other than the substitution of 2.6g p-Aminophenol for 6g Metol (a significant change), the rest of the formula is virtually identical to Edwal 12 with some acid to lower the pH.

    I'm a little obsessive and I make two sheets of everything I do. I use Germain's Finegrain as my go to developer and prefer it to Edwal 12. I have a huge supply of spare exposed sheets to use for developer play like this (read as hundreds) and you never know when the magic bullet will appear! I like solvent developers even for my biggest formats..I'm not a fan of edge effects and jangly sharpness. I do 11x14 because it can resolve tonal qualities better than small formats and I prefer the smooth result of solvent developers. I'm also using soft focus brassies on 11x14!!! Thanks for the input..Evan

  6. #6

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    3,944
    Super-additivity falls out very nicely from the Kendall-Peltz rule. For supur-additivity to occur one developing agent must contain an amine group and the other two hydroxyl groups. Thus we have the classic MQ developer. For Super 20 there is no super-additivity for any of the developing agents. Paraphenylene diamine is a very slow acting developing agent which is used primarily for its silver halide solvency properties. I cannot see any use for paraphenylene diamine with modern emulsions.
    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. #7

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,857
    Agreed. So what is the p-Aminophenol doing in this formula? Its threshold pH to act as a reducer of any consequence is a lot higher than the target pH of this formula.

    Seems like in the end it is essentially a solvent Glycin developer with PPD mostly acting as an additional solvent. So basically a fancy looking formula for what is essentially a Sease #2-4 type developer.

  8. #8

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    3,944
    A staining developer has to necessary characteristics. First it must have a very low sulfite (preservative) level. Second it must contain either pyrogallol or catechol. Super 20 does not meet either of these two requirements let alone both of them. It certainly is NOT a staining developer as judged from the formula.

    BTW, hydroquinone may be made to stain under very specific conditions but is not usually used for that purpose.
    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. #9

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    3,944
    At the time that Super 20 was formulated the developing process was not very well understood. It's not surprising that combination of ingredients is not effective. Look at Champlin's odd mixtures.

    As far as pH is concerned Metol is used in the very low pH D-25 (pH ~7). As to the relative activity of Metol and paraminolphenol at low pH I would have to research this.

    I personally wish that "The Film Developing Cookbook" had never been published. It seems to legitimize a lot of very dubious, obsolete formulas that are best forgotten. The book ignores the fact that today's films are very different from those in use when these older formulas were concocted. And then as I have said over and over again "There is no Holy Grail" of developers. The search for this fiction only distracts people from the object of photography which is to take pictures.
    Last edited by Gerald C Koch; 06-12-2013 at 11:35 AM. 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

  10. #10

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,857
    Why the reference to staining developers in post #8? I was referring to the 4 V.B. Sease superfine grain formulas. They each contain 90g/l Sulfite and 10g/l PPD. #1 is just those two ingredients. Film speed is exceedingly poor. #2, 3 and 4 call for the addition of Glycin at 1g/l, 6g/l and 12g/l respectively. Functionally I'd then argue Edwal Super 20 is very close to Sease #3 with a slightly lower pH.

    Regarding the relative activity of Metol and p-Aminophenol, there's a good table in Haist showing the results of an analysis by Dickerson of the threshold pH values for developing agents (based on a given concentration and a development time of 60s at 90F). I don't have the book in front of me but I believe Metol was 7.25. p-Aminophenol was in the upper 9 range though I can't recall the exact number. However that particular analysis was aimed at figuring out the threshold pH for the developer to work in a reasonable amount of time. There must by some functionality at slightly lower pH values if development times are extended since I believe the pH of D-25 is 7.

Page 1 of 3 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin