How to super activate Pyrocat-HD

Discussion in 'B&W: Film, Paper, Chemistry' started by sanking, Dec 5, 2004.

  1. sanking

    sanking Member

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    In case anyone is interested I posted a message this afternoon at the AZO forum on increasing the energy level of Pyrocat-HD, at http://www.michaelandpaula.com/mp/AzoForum/one.asp?ID=5999&PgNo=&GID=5999&CID=2

    This information should be useful primarily to photographers working with AZO #2 and with alternative processes such as carbon, Pt/Pd and VDB with medium and low contrast films in low contrast lighting conditions. These conditions require developers of high energy to provide the CI necessary for these processes, where a CI of 0.75 is considered normal for N or SBR 7 development.

    The variation of the Pyrocat-HD formula, which I am calling Pyrocat+, consists of adding 0.1g of ascorbic acid per liter of working Pyrocat solution. Adding this amount of ascorbic acid provides a significant boost to the energy level of Pyrocat-HD, without killing the stain, and will shorten times significantly with both the regular 1:1:100 and 2:2:100 dilutions. However, the primary benefit of the the variation would be for developing negatives exposed in low contrast lighting for processes that require a very high negative CI. And, since the stain is not affected by the ascorbic acid the benefits of the variation are equally pertinent to both AZO #2 and UV sensitive processes.

    Sandy
     
  2. mark

    mark Member

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    You really are a wealth of Knowledge. Would this help BPF 200/Classic 200 in low contrast situations as well?

    In the post on the AZO forum you mention a dilution of 5:3:100. I don't follow the Azo forum anymore, so I have no idea what this dilution is about. What would this dilution be for? Over here I see 1:1 or 2:2.
     
  3. Donald Miller

    Donald Miller Member

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    I read the post on the Azo forum and found that my questions had been answered, forgive this post.
     
  4. Francesco

    Francesco Member

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    Mark, the inherent characteristics of the film cannot be meaningfully augmented by Pyrocat+. In other words, Classic 200, in my experience, does not have a high enough CI to print well on new G2 AZO (at least most of the time) and using Pyrocat+ will not change that. Once a film's maximum CI is reached that is it.
     
  5. sanking

    sanking Member

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    Donald,

    The use of ascorbic acid is not an addendum to my earlier post about super activating with sulfite. The earlier post was designed to address one specfic issue, how to get as much contrast as possible out of old Super-XX film when printing on AZO.

    However, as I noted at the time, the use of sulfite in the working solution is bad for alternative printing because it kills the stain, thereby lowering the overall conrtrat of the negative, even though the actual silver density may be higher.

    What I have done with the use of ascorbic acid is give a significant boost to the developer activity of Pyrocat-HD, with any dilution ranging from 1:1:100 to 6:4:100, simply by adding 0.1g of ascorbic acid to the working solution. The purpose is to get as much contrast as possible from low and medium contrast films in flat light situations that are to be printed with UV sensitive processes.

    Quite a number of folks have discussed the super-additivity of ascorbic acid with pyrogallol and pyrocatechin and there is a specific model that also combines Pyrogallol + Metol + ascorbic acid, i.e. the formula introduced by Harald Leban originally as ABC+, now sold as Rollo Pyro. When I originally developed the Pyrocat-HD formula back in the late 90s I experimented with the addition of ascorbic acid to the basic formula but abandoned the experiments because ascorbic acid in the amounts I tried, 0.5 to 1.0g per liter of working solution, killed the stain. Recently, motivated in part by Pat Gainer's experiments with ascorbic acid, I looked at the matter again and decided to try even smaller amounts of ascorbic, ranging from as little as 0.05 to as high as 1.0g per liter of working. The magic figure turned out to be about 0.1g per liter of working solution. At this amount there is a significant boost in the energy of the working Pyrocat solution, B+F is kept at a very low level, and the stain is retained.

    If you were to compare the active reducing agents in a liter of working soluiotn of Rollo Pyro 2:4:100 and Pyrocat-HD 5:3:1:100 here is what you would have.

    Rollo Pyro 2:4:100
    3.0g pyrogallol
    0.4g metol
    0.1g ascorbic acid

    Pyrocat-HD 5:3:1:100
    2.5g pyrocatechin
    0.1g phenidone
    0.1g ascorbic acid.

    At these dilutions the Pyrocat-HD solution is quite a bit more energetic and will develop a film like FP4+ to maximum CI, about 1.2, in slight less than 12 minutes (rotary development at 72ºF).


    Sandy
     
    Last edited by a moderator: Dec 6, 2004
  6. sanking

    sanking Member

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    Mark,

    The dilution would be for persons printing with alternative processes that require a very high CI in the negative, and even more specifically when using low and medium contrast films in low contrast lighting situations. Silver printers, outside of AZO, should never have any need for this extremely active dilution.

    And no, it would not help BPF very much. The problem with BPF is that it has very limited expansion and contraction potential and a relatively low maximum Dmax. I could state that positively by saying that it has excellent exposure and development latitude and when you expose it in the right lighting conditions it is almost impossible to make a catastrophic mistake in exposure or development. The very strong dilution of Pyrocat+ will develop BPF must faster than the regular 1:1:100 dilution but it will not give it more Dmax or make it better for N+ and N- development.

    Sandy
     
  7. gainer

    gainer Subscriber

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    It is possible to increase the CI above that of the maximum silver image by using a staining developer. The stain image is added in proportion to the silver image for blue or UV sensitive printing materials as well as for VC papers with blue or magenta filtration. Furthermore, a silver image formed by a non-staining developer can be increased in contrast by bleaching in a ferricyanide-bromide solution and redeveloping in Pyrocat or other staining developer.
     
  8. Peter Schrager

    Peter Schrager Subscriber

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    Feri-bromide solution

    Mr. Gainer-could you please list the ingredients for the Ferricyanide-bromide solution?
    Thanks Peter
     
  9. clay

    clay Subscriber

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    I'lll chime in. For bleach and redevelop, it is only critical that you completely rehalogenate the image forming silver. So the chemical amounts just affect the time it takes to accomplish this. Try this:

    15g potassium ferricyanide
    15g potassium bromide
    1 liter of water

    Presoak the neg in a tray of water for five minutes or so, then put it into this bleach until the image is basically gone. The image will pretty much go away leaving a tannish looking very faint residual image. Rinse the bleach off in gently running water then redevelop in the developer of your choice. This is also a good way to make a Polaroid type 55 negative suitable for alt processes. i would suggest trying this on scrap negatives until you get your process nailed down adequately. Don't make your first attempt on 'Moonrise at Hernandez'
     
  10. Peter Schrager

    Peter Schrager Subscriber

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    Thanks

    Clay-thank you very much for the information. I'm off to try it this morning
    Have a great day
    Peter
     
  11. gainer

    gainer Subscriber

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    Clay got it.

    I don't want to confuse you with facts, but in the process of experimenting with bleach and redevelop, you may want to try hydroquinone. Without sulfite, it produces a stain and relief image. Since development is to be carried to completion anyway, a very simple concoction of 1 teaspoon of hydroquinone and 1 teaspoon of sodium carbonate in 1/2 liter of water will do. There can be no more grain or fog than there was to start with. The color of the stain may not be ideal for some, but it's worth a try. Of course, catechol (AKA pyrocatechin) is good as well, but more expensive, and most of us will have some hydroquinone on hand. In any case, use the redeveloper very soon after mixing it.
     
  12. Michael Mutmansky

    Michael Mutmansky Member

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    Let me add a note about the bleach and redevelop procedure mentioned above...

    I have found that it can cause a much higher B+F stain than you might expect from the developer otherwise, so you will need to be careful that you do not make a negative that has so much B+F stain that it is very difficult to print with alternative processes. If you aren't printing with alternative processes, it's probably nothing to be concerned about.

    Also, this procedure will do nothing useful for an underexposed negative, only for a negative that has full shadow detail to begin with, but isn't contrasty enough for the process you like.

    You can also bleach and redevelop a negative that was originally developed in a staining developer, but the stain response will be very strong, so I would think twice about doing this without extensive testing beforehand.


    ---Michael
     
  13. gainer

    gainer Subscriber

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    Of course it is true of any intensification that it cannot intensify what is not there. I have seen some negatives that looked as if there was nothing in the shadows that showed detail after intensification. You have seen, I'm sure, negatives in which you could only see a positive image by reflected light at just the right angle of incidence. That is a sign of drastic underdevelopment, which can be helped by intensification.

    It is true that whatever base fog is in the negative will be stained. That is not often a problem in underdeveloped negatives I have seen. "Extensive testing" is a bit of an exaggeration, IMHO. One test should do it. I often have a whole roll that was underdeveloped of which only a few are worth saving. One of the unworthy ones is sacrificed for the good of the worthy.
     
  14. Michael Mutmansky

    Michael Mutmansky Member

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    Gainer, I get the impression that you don't print with alternative processes.

    As I said in my original post, it is easy to dismiss the B+F buildup if you are printing silver, but if you are printing with an alternative process, you have the be careful that your results are suitable due to the extremely low sensitivity of many of the alternative processes.

    When I mentioned extensive testing, I was specifically talking about bleach and redevelop of previously stained negatives. The UV B+F of these negatives can shoot very high without much effort when using the bleach and redevelop approach. I personally wouldn't throw a negative I cared about into the soup until I have tested and printed a few different A:B:H2O mixes to determine which one will produce a reasonable result for the printing process that I intend the negative to be printed with.

    Of course, if anyone wants to be cavalier with their negatives, that's their business.

    ---Michael