Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,906   Posts: 1,555,860   Online: 883
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 18
  1. #1
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,183
    Images
    65

    Some thoughts on seasoning and steady state

    I have been reading several threads lately that discuss replenishment and several older threads stick in my mind that covered steady state seasoning and replenishment.

    It seems that there is a great misunderstanding over the situation with both seasoned developers and with the steady state of seasoned developers.

    First off, let me state that I fully understand that by many definitions, steady state excludes startup and shutdown of a given process. Now, understand this. If, in photography, steady state did not include startup and shutdown, a lot of customer’s films would be ruined every time a photo lab charged their machine(s) with new developers. The startup in a photo process must yield the same results as the seasoned one as closely as is possible.

    In the case of D-76, it is achieved by D-76 as startup and D-76R as replenisher. Each of these have different formulations and used separately would yield different results. Used properly, they will give you a constant result from startup to shutdown thus giving the effect of a steady state condition. The tank developer does not resemble either the fresh developer or the replenisher (see below).

    In other words, fresh D-76 and replenished seasoned D-76 should give close to the same results. I know that there are some differences, but this is due to unavoidable leaching of development byproducts and chemistry into the developer by the wide range of films being put through the process and which cannot be perfectly compensated for due to the variety of films one may use.

    In the final analysis, the steady state may yield the same characteristic curve, sharpness, speed and grain as the fresh developer, but it does it by a slightly different chemical composition. So, for example, the final seasoned D-76 in the tank contains Iodide and Bromide and neither the startup developer nor the replenisher did. But, the seasoned developer also has a different blend of HQ, Metol and alkali. This balance is changed to reflect not a steady state in chemical analysis necessarily, but rather, as closely as possible, it represents a steady state in the film’s characteristics when processed in the ever changing developer. In other words, the film’s steady state remains constant from startup through equilibrium and no customer film is lost even though the chemistry in the tank is undergoing a change from startup to steady state or equilibrium.

    Even some excellent engineers and chemists seem to miss this point. Since it is not a generally published topic, nor is the condition easy to analyze for, it is often misinterpreted or overlooked. I thought I might shed some light on it.

    So, steady state can refer to the condition of the developer solution composition, or to the state of the results obtained from the process, or both. In photography it mainly refers to the results obtained. And, in so doing, it must encompass the startup and continuous running or we would be ruining a lot of customer film in photo labs. I think that you can see that what I have described above is obvious.

    A photofinisher cannot run blank film through his process to season a fresh tank of developer. It is not cost effective. The developer must be right at startup. The same goes for us when we mix up new developer. We must not be required to season that developer. It must be at a steady state at startup to yield the proper results.

    I hope I have clarified things for some people.

    PE

  2. #2
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,327
    Images
    148
    But seasoned/used D76 doesn't ever give quite the same results as fresh D76, nor do other developers used in a similar way.

    We aren't disagreeing because the in fact the seasoned/replenished D76 has some characteristics of D76 used fresh FS and others more akin to diluted 1+1/1+3 which are actually beneficial to sharpness, tonality , and finer grain.

    Variations to replenishment have been made for similar commercial developers depending on whether the replenishment is on a bleed system or topping up. (Axford & Kendall's Ilford Commercial PQ variant of D76).

    Ian

  3. #3
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,183
    Images
    65
    Ian;

    I did say it was not exact, but the alternative is a very large difference between fresh and seasoned. There is no huge difference. The actual differences are very tiny or customers would reject their film as being misprocessed. I think you can agree to that.

    PE

  4. #4
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,327
    Images
    148
    I did qualify my comments in paragraph two by saying that the differences are actually beneficial, there are improvements in quality.

    That's why I'm a strong advocate for using replenished developers where possible. Over the years (since 1969) I've used Microphen (ID-68), ID-11/D76, Adox borax MQ as well as Xtol replenished, either in deep tanks or 2.5 litre containers. All those developers are superb replenished and negative qualities improve compare to using fresh developer at Full Strength.

    Ian

  5. #5
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,183
    Images
    65
    I think you will find that the average user can usually not spot the difference. Or, that the difference is not important enough to comment on, and that is my point. The developer varies quite a bit as it seasons and is replenished, but the final result varies hardly at all. And, the variation is not important to the average user.

    PE

  6. #6
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,327
    Images
    148
    In a commercial situation where 3 photographers were using a 5 litre deep tank system we all found quite a significant increase in negative quality once a fresh batch of developer was seasoned & ripened properly.

    The ID-11 (D76) was worked hard with probably an average of at least 5 or 6 rolls of 120 & a dozen 5x4's being processed every day, no-one particularly liked being the first to use the freshly mixed & seasoned developer, even worse was when a batch was contaminated and we had to use completely fresh developer.

    There's definitely a noticeable difference in using well replenished D76 compared to fresh D76, in terms of negative quality which shows in the final prints.

    But as you say not everyone might spot the differences.

    Ian

  7. #7
    BetterSense's Avatar
    Join Date
    Aug 2008
    Location
    North Carolina
    Shooter
    35mm
    Posts
    2,876
    I use replenished D23. I mix up a new batch when I have added 1/2 the original volume of replenisher.

    In the final analysis, the steady state may yield the same characteristic curve, sharpness, speed and grain as the fresh developer, but it does it by a slightly different chemical composition. So, for example, the final seasoned D-76 in the tank contains Iodide and Bromide and neither the startup developer nor the replenisher did. But, the seasoned developer also has a different blend of HQ, Metol and alkali. This balance is changed to reflect not a steady state in chemical analysis necessarily, but rather, as closely as possible, it represents a steady state in the film’s characteristics when processed in the ever changing developer.
    I think I understand what you are saying here. In other words, developing films changes the chemical composition of the developer, and the replenisher is designed to do whatever it needs to do to compensate for these changes--not necessarily to remove them--so that the final result is (approximately) constant throughout the use.

    What are your thoughts on "seasoning" a new batch of developer with a bit of the old heavily-replenished developer? A help for consistency or just an unnecessary contamination of the fresh batch?

    I think you will find that the average user can usually not spot the difference. Or, that the difference is not important enough to comment on, and that is my point. The developer varies quite a bit as it seasons and is replenished, but the final result varies hardly at all. And, the variation is not important to the average user.
    Perhaps I am an average user, and I can back you up on that. People have told me that there are differences, and that I should use one-shot chemicals for consistency, but I've never noticed any differences between fresh developer and well-replenished developer. I don't see how you could detect small differences anyway if you are shooting roll film.
    f/22 and be there.

  8. #8
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,183
    Images
    65
    Well, you can use any method you want, the basic system is designed to work with batch replenishment or by using flow meters. As for the variations between fresh and seasoned, it is there, but in terms of quality, it is minor. After all, fresh and seasoned color processes work just fine except for a tiny shift in color balance in some cases. I think that even this has been worked out in recent years.

    At Cape Canaveral we ran thousands of feet of MP film a month and did not have to "run in" fresh developer before quality was up to release standards. In the lab I worked in in college, we did not run in. And, at Kodak we worked with fresh developer and measured release standards, while the release technicians worked with seasoned developers. Our data were comparable in terms of all release characteristics within tolerances.

    PE

  9. #9
    fotch's Avatar
    Join Date
    Mar 2005
    Location
    SE WI- USA
    Shooter
    Multi Format
    Posts
    4,157
    Quote Originally Posted by Ian Grant View Post
    In a commercial situation where 3 photographers were using a 5 litre deep tank system we all found quite a significant increase in negative quality once a fresh batch of developer was seasoned & ripened properly.

    The ID-11 (D76) was worked hard with probably an average of at least 5 or 6 rolls of 120 & a dozen 5x4's being processed every day, no-one particularly liked being the first to use the freshly mixed & seasoned developer, even worse was when a batch was contaminated and we had to use completely fresh developer.

    There's definitely a noticeable difference in using well replenished D76 compared to fresh D76, in terms of negative quality which shows in the final prints.

    But as you say not everyone might spot the differences.

    Ian
    Don't take this the wrong way but if you can see it and others do not, maybe this is like the placebo effect. Because you believe in this replenishment effect, you see what you want to see and others don't?

    Just a thought.
    Items for sale or trade at www.Camera35.com

  10. #10
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,327
    Images
    148
    Quote Originally Posted by fotch View Post
    Don't take this the wrong way but if you can see it and others do not, maybe this is like the placebo effect. Because you believe in this replenishment effect, you see what you want to see and others don't?

    Just a thought.
    It's well known that the quality improves, and has been observed by plenty of other photographers and been well written about. But replenishment is rarely used outside commercial darkrooms, and even less so by amateurs.

    Ian

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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