The trouble with Pyro - part 1

Discussion in 'B&W: Film, Paper, Chemistry' started by michael_r, Aug 11, 2012.

  1. michael_r

    michael_r Subscriber

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    I thought I would post some data for discussion - if anyone is interested.

    This is part of a low-flare/no-flare test of 35mm Delta 100 in PMK. One of the purposes is to try for some cold hard yes/no answers to questions like:

    -Is imagewise stain pH sensitive post development?
    -Does imagewise stain intensify if a post-fixer alkaline bath is used?
    -Does an extended wash intensify imagewise stain?

    Rather than test one variable at a time, I wanted to first try an all-out "ideal" treatment ("control") versus a rule-breaking treatement ("pressure"). If there was any significant difference observed between the bookend scenarios, I'd continue investigating the variables.

    The development regime was the same in both treatments. All solutions were mixed with distilled water (with the exception of running wash water). Standard PMK dilution. All solutions and running wash water were at 22C. Post-development as follows:

    Control
    -1 minute running water rinse
    -5 minutes in TF-5 fixer
    -2 minutes in spent developer
    -30 minute wash

    Pressure
    -30 seconds in Kodak Indicator Stop Bath at standard dilution (16ml/l)
    -5 minutes in Ilford Rapid Fixer
    -10 minute wash

    Densities were read with a black and white densitometer to determine "visual" readings. Since I don't own a color densitometer, the "blue channel" readings were then made using a Wratten #47 filter. The results are attached.

    As expected, the silver densities appear to be virtually identical with the possible exception of a very small amount of additional density in the low values in the "control" scenario, which is either simple experimental/measurement variability, or a very small amount of compensating development occuring in the water "stop" bath.

    As for the stain measurements, it is fair to say I am confused. To be honest, what I expected was either no significant difference at all, or a difference in general stain only.

    Key stain observations
    1. Base fog (visual and blue) were the same
    2. "Control" scenario shows more film speed and shadow density from stain
    3. Beyond the zone IV exposure, the increase in stain in the "control" scenario relative to the "pressure" scenario is essentially constant, rather than proportional

    Observations (1) and (3) above would appear to contradict eachother to some extent. The conditions in the "control" scenario seem to add some imagewise stain (ie proportional, contrast-increasing stain) up to a point - the zone IV exposure, after which there is no further increase in contrast.

    How can this be?
     

    Attached Files:

    Last edited by a moderator: Aug 11, 2012
  2. Doremus Scudder

    Doremus Scudder Member

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    Michael,

    You've partially answered your own question. In your "control" scenario you are getting more development happening from reactivated carried-over developer. A short water stop will decrease developer activity somewhat, but not rinse all the developing agents out of the emulsion. Transferring this negative to an alkaline fixer will re-activate those developing agents and give more development until the fixing removes enough of the undeveloped halides to stop development. This development is of a compensating nature, as you guessed, and affects the mid and lower values proportionally more than the higher densities (where the developer will exhaust rather rapidly without making much of a density difference).

    I imagine this happens all the time for people who use alkaline fixers for their film (even if they use an acid stop in between), but is of little importance; as long as the system is tested and calibrated, results will be consistent. I would say you have "discovered" a compensating effect of using an alkaline fixer.

    I'd recommend that you use the same fixer for both tests to eliminate this variable if you wish to test other the other things you mention.

    FWIW, I've stopped using alkaline fixers for film after experiencing streaking from carried-over developer being re-activated in the fix and turning on the light "too soon," i.e., halfway through the fixing time. I'd rather not have to deal with that.

    Best,

    Doremus

    www.DoremusScudder.com
     
  3. michael_r

    michael_r Subscriber

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    Hi Doremus, thank you for responding. A couple of things...

    1. TF-5 is an almost neutral pH (slightly acidic) rapid fix as opposed to TF-4 which is alkaline. I used TF-5 because I had it on hand but I guess ideally in the "control" scenario I would have used an alkaline fix (note I'm referring strictly to PMK in this case because it is much more finicky about pH than Wimberley's formulas).

    2. Re compensating development, the thing is the densitometry here showed the effect on silver density to be very small, possibly even within the margin of measurement error (refer to the two visual channel curves).

    So what I'm really trying to explain are the differences in the blue channel readings, and this is where I'm stumped. Even if there is some small amount of compensating development in the control scenario, why is the apparent difference in imagewise stain so pronounced compared to the difference in silver densities? Why is the apparent increase in imagewise stain in the control scenario not proportional to silver density? If we compare the two blue channel curves, it would appear the additional stain in the control scenario is not only imagewise stain, but is non-proportional. It is only materially affecting the densities below middle grey. It's as though the additional stain gained in the control scenario is "compensating imagewise stain". ?
     
  4. Rick A

    Rick A Subscriber

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    In the Book of Pyro, Gordon Hutchings espouses the use of diluted acid stop bath (50% normal) prior to fixing. This book deals primarily with PMK pyro. He also prefers TF-4 for fixing. This is then followed with a 30 second immersion(continuous agitation) in the spent developer to induce the formation of stain.
     
  5. michael_r

    michael_r Subscriber

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    Rick, The Book of Pyro was part of the reason for this test, since even Hutchings himself now says you only need the alkaline after-bath if your wash water is acidic. My problem with these formulas in general is that most of the recommendations don't come with supporting data, and the proverbial jury always seems to be out on the impacts of various processing procedures on stain. The after-bath is only one example of several variables that may or may not impact general stain or imagewise stain. And unfortunately in the case of PMK, I have been unable to find any definitive testing or conclusions out there. Generally if it isn't Kodak or Ilford, we have to rely largely on anecdotal evidence. For most developers, this is not a huge issue because the variables are limited and testing is relatively straight forward. But when it comes to Pyro, stain can in some cases be a tricky thing. Concerning any Pyro formula I need to understand how to get the following:

    1. Maximum imagewise stain
    2. Solid consistency/repeatability

    Unfortunately the answers are simply not out there. And PMK is the trickiest due to its alkali system and the way in which its stain forms.
     
    Last edited by a moderator: Aug 12, 2012
  6. michael_r

    michael_r Subscriber

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    Speaking of which, does anyone know how I might be able to contact G. Hutchings directly? I'd like to ask for his commentary on this data.
     
  7. bdial

    bdial Subscriber

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    You might be able to contact him via Freestyle. As I recall he is on their "professional's council" or whatever they actually call it.
     
  8. michael_r

    michael_r Subscriber

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    Thanks, bdial. I will try that.
     
  9. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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  10. michael_r

    michael_r Subscriber

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    Yes - but I'm trying to figure out whether there exists such a thing as "compensating stain induction". If yes, it would appear it has a very significant effect on film speed.
     
  11. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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  12. michael_r

    michael_r Subscriber

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    Well I posted my question on the freestyle board so we'll see what happens.
     
  13. Kirk Keyes

    Kirk Keyes Member

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    You should probably use a strong red filter on your densitometer for silver density readings, or at least test your densitometer with a red filter to make sure there is no difference with the filter and no filter.

    You may have seen the spectral scans I made several years ago comparing PMK and PyroCat developer stain. From those scans, you can see the stain has little absorbance in red.
     
  14. michael_r

    michael_r Subscriber

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    Hi Kirk, I get your point in the case of PyroCat, but why would a green stain not absorb red? These Delta 100-PMK negatives are fairly green. Granted the particular green leans toward the yellow (as opposed to blue-green), but the stain is much more green than yellow, nothing like the yellowish color I've seen in some ABC negatives.
     
  15. Gerald C Koch

    Gerald C Koch Member

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    Hi Michael,

    I'm glad that you are looking at staining developers in a critical and studied manner. In the past there has been more wizardry with these developers than in all the Harry Potter books.

    There is also an on-going question concerning stain images stability toward UV and visible light.

    Jerry
     
  16. michael_r

    michael_r Subscriber

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    Hi Gerald, thanks. I guess the thing with me is, I just don't trust everyone's anecdotal evidence - even the formulators themselves. Don't get me wrong I don't want to come off like I'm trashing Gordon Hutchings (by the way I'm also testing WD2D and have been emailing back and forth with Mr. Wimberley who has been very generous with his time so far). I've had some correspondence with Steven Anchell as well regarding a few seemingly contradictory statements in the FDC and DC regarding agitation with staining developers.

    This all started back when I first read The Book of Pyro (after having read Haist etc). What frankly annoyed me was the total lack of clarity and data in a book which is still considered by many to be the bible of Pyro. I read it over and over, and still came away with the same questions regarding things like the over-the-top agitation "requirements", stain characteristics and the effect of the choice of alkali, stain stability, after-development procedures and whether or not they can result in reduced or intensified stain, graininess and the purported "grain masking" effects compared to both solvent and high definition non-staining developers, film speed, variable contrast printing etc.

    There is no data for any of this anywhere that I can find. Suppose I want to use one of these formulas - well, I will never know if I'm getting what I'm supposed to be getting.

    Im only part of the way into this, and already I feel like based on the information I've collected and the data I've accumulated so far, I could write a fairly valuable Second Book of Pyro.
     
  17. Ian Grant

    Ian Grant Subscriber

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    In many ways you're right, the Pyro books don't help as they have some strange ideas, like soaking fixed films in the spent developer :D However the simple answer from experience is some are excellent and deliver what the users need.

    The stability issues seem unfounded as many major collections of negatives were made using developers with far higher staining levels, and even half a centuary (or more) later theres still no issues from negatives printed rather a high number of times.

    Ian
     
  18. michael_r

    michael_r Subscriber

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    Hi Ian, it's true, I'd say the issue of archival stability of the dyes would be pretty much at the bottom of my list of concerns, as I believe it should be for most people (assuming adequate storage of negatives that does not lead to premature degradation due to sloppiness)

    After all, with all due respect to everyone here, it is not as though any of our negatives need to outlive us.
     
  19. Gerald C Koch

    Gerald C Koch Member

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    The only reason I mentioned the light stability was a fairly recent post where a negative was left on a table in sunlight and suffered fading. Part of the negative was covered so the fading was readily visable. As with all dyes a stain image will fade. The question is how fast. Years ago the trick to use with a color slide that was too dark was to expose it to sunlight for awhile. My concern is negatives used in alternative proceseses using sunlight exposure. Will long or multiple exposures cause fading?
     
  20. michael_r

    michael_r Subscriber

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    Very good point. I hadn't even thought about UV processes.
     
  21. Ian Grant

    Ian Grant Subscriber

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    There's a degree of staining with many developers containing Hydroquinone and the stain component of most modern staining developers is relaively small compared to early staining developers.

    Even an unstained negative (or print) can be affected by prolonged exposure to bright light, particularly sunlight, a silver sheen forming in the emulsion surface, worse if the emulsion's been poorly fixed and/or poorly washed. It's always been recommended that negatives are stored in the dark.

    There's plenty of stained negatives around that have been contact printed a great many times over the past decades and are still producing high quality prints today.

    Ian