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Thread: Discussion: Pyro stain, silver rich film & thick emulsion

  1. #1

    Discussion: Pyro stain, silver rich film & thick emulsion


    I often hear folks referring favorably to films as being "silver rich," or "thick emulsion." These are supposed to be desirable qualities of films from yesteryear, especially when used with Pyro developers. I would like to hear from folks that have used these "magical" films from yesteryear, as well as those versed in chemistry, because I'm having a hard time believing there's something "special" about them.

    I heard folks claim that silver rich films stain better in pyro. Pyro stains proteins; it was used in the 1800's as a tanning agent, as it would react with the protein in animal hides. So how does it stain better with silver? I don't believe it does. I believe it reacts with the proteins in the gelatin that forms the emulsion and has nothing to do with silver content. Can any chemists confirm this?

    Thick emulsion, would certainly seem to have a greater affect on stain, as there would be more protein, but OTOH is thick emulsion better? It would seem that the thicker the emulsion the less sharp an image would be due to diffraction. This would be especially true of negatives that were destined for the enlarger.

    Super XX may have been a "special" film, though I have never used it. From knowledgeable people that have used it, I understand that what made XX unique, was it's linear response to red, green and blue light; not the fact that it may have been silver rich, or a thick emulsion. I believe many of the films made today are quite good, perhaps even better that yesteryears films, just different. Is there anything to silver rich, or thick emulsion films being truly better, or is it myth?


    Regards, Pete

  2. #2

    Join Date
    Jan 2001

    Discussion: Pyro stain, silver rich film & thick emulsion

    Do your own darkroom work, Pete?
    Wilhelm (Sarasota)

  3. #3

    Discussion: Pyro stain, silver rich film & thick emulsion

    The best negative I have ever attained (in terms of sharpness, detail, etc.) in about 15 years of 8x10 work has been with Pyrocat HD and Efke PL100. My decision to try Pyrocat was my own. I understand your skepticism especially when words like "magical" are involved. But to be fair, only you can decide if what people say are true. Please try it out if you have the time and frame your own opinion as I have. Only then can you make sweeping statements about "old style" versus "new style".

  4. #4
    Whatever David A. Goldfarb's Avatar
    Join Date
    Mar 2000
    Honolulu, Hawai'i

    Discussion: Pyro stain, silver rich film & thick emulsion

    The advantage of the old "thick emulsion" films was that they had a long scale that worked well with processes like platinum/palladium or chloride papers like Azo and Haloid Industro. Super-XX had gold chloride that also contributed to its long scale.

    "Silver rich" is probably advertising hype in many cases, but what it stands for is density range. Pyro developers increase density proportionally and can improve highlight separation, so they add to the film's density range, in addition to other effects like grain masking and improved acutance due to the tanning of the geletin.

    I'm not sure why, but for whatever reason pyro developers seem to work better with traditional films than with T-grain films.

    Efke PL 100 is not a "thick emulsion" film, but it is a single layer, traditional grain film, and it does look great in PMK.

    I recently tried Ektapan (alas discontinued, but there's still some around, and I had some in the freezer), which I thought was completely flat and uninteresting in D-76, but in ABC pyro 1+1+1+7 it produces beautiful results for portraits.

    Tri-X is another film that I like in PMK for enlargement or ABC for contact printing.

  5. #5

    Join Date
    Sep 2003

    Discussion: Pyro stain, silver rich film & thick emulsion

    My personal experience with traditional so-called “thick-emulsion high-silver” films is that they are grainy.

    A true darkroom “artiste” can do magical things with grain in high-acutance and highly-diluted developers as well as Pyro. I once made a nude high-key mural from a 35mm Tri-X negative developed in Ethol T.E.C. Wow!

    I find Delta 100 extraordinarily sharp and grainless. Much more so than the old films like Efke. But I can’t get it to DO anything. It’s like a great hair stylist trying to work with a patron who has a crew cut.

  6. #6

    Join Date
    Sep 2003

    Discussion: Pyro stain, silver rich film & thick emulsion

    Who cares?

    If Efke PL100 is thick emulsion, that may be the reason why I get such satisfying results with it. If it's a really thin emulsion, then it just goes to showya that there's not much to the adulation given the "thick emulsion" films of yore. In other words, I couldn't care less whether they lay the emulsion on with a trowel or if it's only 1 molecule thick. It's beautiful film in either case. I just ordered another 10 rolls and 100 sheets of it a few minutes ago.

    As to Super XX: the only people who could conceivably care about how it compares to any film made today are Michael Smith and Paula Chamlee. That's because only they possess any significant quantity of it. Their interest would only be to determine if there's anything out there which could give them better prints. As to the rest of us, why would we ever care about anything we can never use?

    When last I talked to Michael he told me that soon he will do the long awaited tests of modern films that he's been talking about on the Azo forum forever. He will compare many modern films to Super XX because he wants to see if the unique look he and Paula get in their prints is due to the film. I immediately said to him, "It's not the film. If it were the film, Joe wouldn't be getting such glorious prints from Efke and Tri-X. If it were the film, then you wouldn't be able to extract such glowing prints from my wafer thin Bergger negative like you did." It's not the film. It's the photographer and how he uses the film. I also get some really glowing prints from 400TMax negatives developed in pyro, and it's for sure they're not thick emulsion.

  7. #7

    Discussion: Pyro stain, silver rich film & thick emulsion

    Thanks for the replies so far. I posted this not because I'm looking for any sort of majic bullet, but rather trying to understand what folks are saying when they talk about silver rich films. Personally, I think it's hype, but I'd like to remain open minded and maybe there's something I don't understand.

    I have been doing all of my own darkroom work for quite some time and I do use pyro developers. One of the reasons I'm asking these questions is because I can achieve more than 2.5 D.U. on modern thin emulsion films, so what does silver rich offer? Pyrocat is my standard developer and I use Efke, Ilford & Kodak films with great success. I'm not looking to change my materials or methods, just understand what others are talking and sometimes whining about.


    Regards, Pete

  8. #8

    Discussion: Pyro stain, silver rich film & thick emulsion

    Pyro is still in use as a tanning agent. It is used to tan leather.

    Thick emulsion films will not increase diffraction, which is a function of the aperture of the lens. They will increase irradiation--the spreading of light through the emulsion as it hits the emulsion. Noticeable with overexposure. Did you ever overexpose and find that there was density on the borders of the film that looked like it leaked out from the image area? That is from irradiation, which is different from halation, which is the light spreading through the emulsion as a result of rebounding off of the base of the film after it is gone through the emulsion. Modern films, including Super XX, have anti-halation backings and halation is not usually a factor.

    Thick emulsion films had more latitude than modern thin emulsion films. You could over and under develop them by a significant amount. As a result, with thick emulsion films and proper development, it is easier to get good printable negatives from most any type of lighting situation--from exceedingly flat (1/2 stop difference in the scene) to exceedingly contrasty (over 15 stop difference in the scene) than it is from modern films. As photographers, all of us are limited by our materials. I have long believed that those who restrict their photographing to even light situations do so because the modern thin emulsion films they use cannot handle excessive contrast.

    So, thick emulsion films indeed do have their advantages. Whether they are also silver rich I do not know. Many things go into an emulsion and affect density besides the amount of silver.

    Some years ago a friend of mine who is a chemist analyzed a number of different papers. He found that the one with the richest blacks were not necessarily those with the most silver in them.

  9. #9
    All metric sizes to 24x30 Ole Tjugen's Avatar
    Join Date
    Mar 2002

    Discussion: Pyro stain, silver rich film & thick emulsion

    I doubt there are any thick emulsion films currently in production. The EFKE films are based on the ADOX films, which were the first thin emulsion films. But I do know that some "old-fashioned" films like EFKE, FP4+, APX 100 and the like are far more responsive to variations in developing than the T-grain/Delta-grain films. Since they also seem to have more latitude in exposure, the choise is easy for me: Old-style films, adjust developer until right.

    So I have dismissed the question of silver content and emulsion thickness as utterly irrelevant. I know what I can do with these films, and I can't get it to work on Deta/T-grain films.

  10. #10

    Join Date
    Sep 2003

    Discussion: Pyro stain, silver rich film & thick emulsion

    There is one way to verify the claims by manufacturers of "old style thick emulsion" attributes of their films. Try water bath development of negatives with a horrendously wide contrast range. (See The Negative, by Ansel Adams. page 229 unless memory serves me ill) If it works, the film is indeed of the 'thick emulsion' type. If not, then it isn't.

    I've long been meaning to try this with Efke film, but haven't had the need. It handles all the contrast I can give it without blocking up.

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