Chemical catalyst

Discussion in 'B&W: Film, Paper, Chemistry' started by martellsv, Sep 19, 2012.

  1. martellsv

    martellsv Member

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    If one developing agent work slowly, could i use a catalist to improve the speed, reducing the induction period?
    considering the propierties of the catalist.... over the silver halide...
    Thanks Alejandro Spain
     
  2. michael_r

    michael_r Subscriber

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    Not sure exactly what you're asking, but the activity of typical developing agents increases as pH increases. Developers contain an alkali "accelerator" for this purpose. Is this what you're referring to, or are you referring to an actual catalyst?
     
  3. Gerald C Koch

    Gerald C Koch Member

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    I have the same problem as Michael has. What is the purpose of your question? Is it merely curiousity or is there a practical reason for your question. Without more information it is hard to give an answer.

    To add to what Michael said, the activity of a developing agent increases with temperature. In certain cases there are chemicals that can be added to a developer to increase its activity. These chemicals reduce the charge barrier effect. For example certain quartenary salts can reduce the induction period. Mason in his book Photographic Processing Chemistry Chapter IV discusses the mechanism of development in detail.
     
  4. martellsv

    martellsv Member

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    For example certain quartenary salts can reduce the induction period.

    I tried to use one ammonium quaternary salt, but i understood some work better than other salts that i haven't got.... perharps imidazoles? Moersch use it with only Hydroquinon developers you can find the MSDS easily. That book is hard to find in Spain, and in the www.
    IMHO, (using a metal calalist) change the shape / structure of halide crystal to offer no resistance to the penetration of developing agent (only Hydroquinone) perhaps metal (copper or manganese Mno2 perhaps). no, I'm not chemical is an idea ... stoichiometrically no change ... Perhaps This will change the ionic status negativ-negativ (repulsion) to neutral-negativ Thanksssss
     
  5. Rudeofus

    Rudeofus Subscriber

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    Be aware that MSDS only list toxic components and only those which are contained in sufficient amount and then only those which are not proprietary. If MSDS would tell you the whole story, Fuji would fix with sodium metabisulfite only ...

    A number of development accelerators have been described in patent literature. I don't think you want to change the shape/structure of the halide crystal, since these are carefully designed to have exactly the properties they have for optimum results.

    Some have already mentioned alkali, which increases developer activity of most common developers. You brought up tertiary ammonium salts, note that tetramethyl ammonium salts are extremely toxic even with skin contact, so you might stick with tetrabutyl ammonium salts, which are affordable and obtainable. US patent 5962202 describes a developer with tertiary ammonium salts and ascorbic acid. While Phenidone and Metol are not catalysts (as I have been told), they do reduce the induction period for Hydroquinone, Catechol, Ascorbic Acid and others.
     
  6. martellsv

    martellsv Member

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    Neutralize

    tetrabutyl ammonium salts, ok Thanks,

    I wonder if putting a metal deposit I can try to neutralize the barrier, not change the halide with a catalist, I don´t Know thanks... I think this function can´t be supplied exactly with alkalies... for several reasons, prehaps the most important is if you want to take an elevator to the sixth floor down not settle for the third, and if you can do it in 6 minutes better than in twelve, thanks
    I am convinced of the qualities of hydroquinone beyond of Metol and PD, in some cases
     
  7. pgomena

    pgomena Member

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    Doubling the concentration of your developer will decrease time, if that's what you're really after. Look at the development times for HC-110 A versus HC-110 B, or Rodinal 1:25 vs. 1:50 or 1:100.

    Peter Gomena
     
  8. Rudeofus

    Rudeofus Subscriber

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    Do not put any metal near the grains, or no developer will ever be able to distinguish between exposed and unexposed grains! An exposed grain has maybe only a few silver atoms, you better don't mess with these and you sure don't want to put metal atoms on unexposed grains, or you might as well substitute your dev with black spray paint.

    You are correct. Alkalis increase the reduction potential of common dev agents, but don't make the HQ/AA stick to silver any better. A nice example for this is HQ which reduces silver halide in caustic environment, whereas Quinone is a good (albeit smelly) bleaching agent in acidic environment, i.e. you can even reverse the direction of the reaction with pH.

    Can you give us any indication why you are so convinced of this? Is it just gut feeling or do you have some experimental data to support your stance?
     
  9. martellsv

    martellsv Member

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    Emulsion

    I think is possible put traces of Gold, in the emulsion to sensitize it e.g, i have experimented with iron compounds (other reasons and sorry i haven´t seen the effect you have described)....
    I think it could be chemicali possible to fatten the silver... with metal incorporating it into the filaments of silver with very few traces (but this is not the reason)...
    A catalist is possible with very few quantities to neutralize the barrier ?????

    Probably you have the reason... i only try to undertand more...thanks
    I think like explain the hydroquinone cuestion...thanks
     
  10. Photo Engineer

    Photo Engineer Subscriber

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    Gold added at the rate of about 1 part to 3 parts of Sulfur are used in making the emulsion, but during processing Gold has little (if any) effect. Cobalt Hexammine and Hydrogen Peroxide are known to be heterogeneous catalysts in color development, but this is not what you are looking for.

    PE
     
  11. Prof_Pixel

    Prof_Pixel Member

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    Ah yes, good old RX chemistry!
     
  12. Photo Engineer

    Photo Engineer Subscriber

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    Yep!
     
  13. Rudeofus

    Rudeofus Subscriber

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    As already explained by PhotoEngineer, this is done during coating, not during development. It's an almost 80 year old technique. Since it is already done, rest assured that there is no need to add extra. Film manufacturers generally know their trade ....
    You have experimented with iron compounds, not with metallic iron, there's a big difference. Iron compounds, depending on their concentration, membership in a complex and their oxidation state, will either develop silver halide or bleach silver. This is all described in common photographic literature.
    To give you some perspective: PhotoEngineer, our leading expert here on APUG, wrote a book which describes how to make and coat emulsions. It's the best and most advanced publicly available book we have on this topic. His top emulsion reaches ISO 40 with common developers. Compare this to Tri-X (ISO 400) and Delta 3200 (ISO 1200), and you see how far we are behind with our amateur means. Let's be realistic, "fattening silver" is not going to improve Tri-X.
    That's exactly what Phenidone and Metol do. Supposedly some tertiary ammines do it as well, but to my best knowledge they are not used in commercially available developers.
    There is no hydroquinone question. This compound has been around for over hundred years and is very well understood. Developers have been formulated with hydroquinone alone. Haist's book describes its development action under high pH where it develops alone. It doesn't really do anything special.
     
  14. martellsv

    martellsv Member

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    On equestion

    It is late, i have a beer and soon i will go to the bed, but, i will only say that my dear friend Noelia Ortiz,
    chemical engineer who phoned yesterday has said me it's possible, stimulate benezo ring and the rest...

    A lot of compounds that you use in a developer has been shared, and used in a emulsion...don't you know? See Agfa APX 100 and 400 developed in the same time...
    Use a catalist is possible "Si se puede". Iam tired it's late tomorrow see you... thanks a lot
     
  15. martellsv

    martellsv Member

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    Catalist. I have never said i have the reason, i am only tring to understand.
    For example in industrial applications, certain iron compounds has been used like catalist, not metallic Iron (not heterogeneus catalist)
    Photographic aplication of Iron Compounds:
    For Example, SLIMT D. Kachel (Prebath) an Iron (II) compound, When i tried i haven´t seen black points or similar...

    PhotoEngineer is wonderfull, perhaps the main reason to write in APUG... Thanks
    Fatten the silver, more compact filaments if you see an enlargement with microscope, or see how is the reflection of the light,
    all combined with Hydroquinone like only agent developer (perhaps with little PD), is like a Harley Davidson compared to
    Yamaha e.g. this is noticiable with 100, 400 Iso not 25 or 50 iso...

    Another thing, if its works the catalist why don´t use it? if not i have learnt a lot with you...
    I am sure you have developed a Tri-x 4"x5" with D-76 homemade, ok now put 11 grs. of Hydroquinone,
    observe the seperation and the density of higligths there is a great diference... (Hydroquinone has nothing to do? really...)


    the next question is the speed enhance?
    because i used the PD like that patent 0,016 but i think is possible the catalist reduce the developement time 12' to
    10' or 8' i do´t know.

    happy to think about your knowledges.thanks
     
  16. Rudeofus

    Rudeofus Subscriber

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    David Kachel suggested a range of compounds for contracting contrast, Fe-II was not among them. Anyway, you will get some development from Fe-II but shouldn't get fogging. Your original suggestion was to deposit metal onto the silver grains, and I maintain that this will cause trouble one way or another.
    You still owe us the source for your obsession with Hydroquinone only developers. As mentioned before, HQ is a very well understood compound in photo chemistry. You most likely won't get a Ducati with an HQ only developer.
    I'd say: go for it!
    Actually, with the low pH of D-76, the Hydroquinone doesn't do nearly as much as you think, and Grant Haist formulated a version of D-76 completely without Hydroquinone but otherwise the same properties! If you just look for higher contrast, there already exist many published and well working recipes for high(er) contrast, no need to mess with D-76.
    See the patent search I linked to previously. You can develop in less than 1 minute if film speed, grain and sharpness are no concern to you.
     
  17. martellsv

    martellsv Member

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    II would like to talk about chemical i think thare is a especific catalist compounds to halides (not heterogeneus)
    I have supoused and assumed that if someone answered my post should know the catalysts is not necessarily a metal could be as metallic deposit
    but starting from a compound having one metal in the case of halides.
    OK is FE-III, sorry a typewriting mistake (your eagle eye) , but have you seen the mottled with black spots with SLIMT NOOOOO!!!! (if well done) you are Wrong in this point... metal is possible And sorry have you ever introduced in your formula Cd, K, Na i think....? jajajajaja

    Read please, I write not what you understand, this is clear... do the test please...if Hydroquinone has nothing to do why the 11 grs. vs 6 grs. is more density? about 0.2 units
    in the same conditions??? you only see, and believe the way you walked, there is another ways... i am tring to understand this question, it's not very clear (you can do this exercise with film and paper with similar results)

    I am not interested in this patent, i have mixed by miself this kind of developer not fully balanced yet ... but i developed 12' TMAX 100... there are compounds you use in developers or in emulsion to obtain similar results, at least with the same idea, e.g. this is agfa and the same time of develope, with film of 100, 400 etc...


    I like Harley Davidson. thanks
     
    Last edited by a moderator: Sep 22, 2012
  18. Rudeofus

    Rudeofus Subscriber

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    Whatever it is you are trying to achieve, you will have to continue on your own from now on, at least without my further participation. Good luck with your efforts!
     
  19. martellsv

    martellsv Member

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    thanks

    Thanks
    Maybe I did not explain well