Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,910   Posts: 1,556,218   Online: 967
      
Page 55 of 55 FirstFirst ... 54549505152535455
Results 541 to 550 of 550
  1. #541
    PhotoJim's Avatar
    Join Date
    Oct 2005
    Location
    Regina, SK, CA
    Shooter
    Multi Format
    Posts
    2,221
    Quote Originally Posted by MattKing View Post
    PE:

    Are aware whether any research work has been done with a goal of developing such tests? Not just for X-Tol, but for other chemicals as well (e.g. E6 and C41). It seems to me that in the current circumstances, such tests would be much more likely to be commercially valuable than when volumes were higher.
    High-volume users have good data already on total development capacity. They don't need to test the chemistry; they can simply replenish or discard based on the amount of film processed in the chemical.

    If you need a developer that will work well after years of storage, XTOL is not your developer, unfortunately.
    Jim MacKenzie - Regina, Saskatchewan, Canada

    A bunch of Nikons; Feds, Zorkis and a Kiev; Pentax 67-II (inherited from my deceased father-in-law); Bronica SQ-A; and a nice Shen Hao 4x5 field camera with 3 decent lenses that needs to be taken outside more. Oh, and as of mid-2012, one of those bodies we don't talk about here.

    Favourite film: do I need to pick only one?

  2. #542
    MattKing's Avatar
    Join Date
    Apr 2005
    Location
    Delta, British Columbia, Canada
    Shooter
    Multi Format
    Posts
    12,577
    Images
    60
    Quote Originally Posted by PhotoJim View Post

    If you need a developer that will work well after years of storage, XTOL is not your developer, unfortunately.
    I know, that is why I currently use replenished HC-110 .

    But I would like to try replenished X-Tol
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  3. #543
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,186
    Images
    65
    We used chemical analysis! And control strops! Thats about it. No simple test.

    PE

  4. #544
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,695
    Images
    10
    Quote Originally Posted by MattKing View Post
    Are aware whether any research work has been done with a goal of developing such tests? Not just for X-Tol, but for other chemicals as well (e.g. E6 and C41). It seems to me that in the current circumstances, such tests would be much more likely to be commercially valuable than when volumes were higher.
    There is such a test and it's called "running a test strip". The biggest problem with this test and Xtol is that (at least according to some accounts) Xtol went from fully working to complety inactive in the brief timeframe between clip test and dev run.

    Mark's suggestion "just add some pH balanced AA to the mix right before using it" seems like the easiest method for overcoming this issue. It should work both with his dev and with Xtol.
    Trying to be the best of whatever I am, even if what I am is no good.

  5. #545

    Join Date
    Nov 2004
    Posts
    1,156
    Quote Originally Posted by Rudeofus View Post

    Mark's suggestion "just add some pH balanced AA to the mix right before using it" seems like the easiest method for overcoming this issue. It should work both with his dev and with Xtol.
    One can calculate how much sodium ascorbate to add assuming all the oxygen in the air space is used up.
    2C6H7O6Na.......................+ O2..........->2C6H5O6Na +2H20
    Sodium ascorbate............ Oxygen.......... Sodium dehydroascorbate
    2x198.1=396.2g................22.4L=107L air
    When the container is opened, add 3.7g sodium ascorbate for each liter of air space above the developer.

  6. #546
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,695
    Images
    10
    Quote Originally Posted by Alan Johnson View Post
    One can calculate how much sodium ascorbate to add assuming all the oxygen in the air space is used up.
    You'd also have to account for all the Oxygen diffusing into the container ...
    Trying to be the best of whatever I am, even if what I am is no good.

  7. #547

    Join Date
    Apr 2008
    Location
    Escondido, California, USA
    Shooter
    35mm RF
    Posts
    669
    Quote Originally Posted by Rudeofus View Post
    You'd also have to account for all the Oxygen diffusing into the container ...
    You'd also need to account for loss from the Fenton reaction, which is hard to predict. When adding ascorbate upon use, it may be best to assume that all the ascorbate has been destroyed.

    Mark Overton

  8. #548
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,695
    Images
    10
    Quote Originally Posted by albada View Post
    You'd also need to account for loss from the Fenton reaction, which is hard to predict. When adding ascorbate upon use, it may be best to assume that all the ascorbate has been destroyed.
    IIRC, the Fenton reaction only catalyzes (read: speeds up) the destruction of Ascorbic Acid, but it is still aerial Oxygen (or whatever other oxidizer is around) which does the oxidizing.
    Trying to be the best of whatever I am, even if what I am is no good.

  9. #549

    Join Date
    Apr 2008
    Location
    Escondido, California, USA
    Shooter
    35mm RF
    Posts
    669
    Some good news about longevity testing of the concentrate:
    It's been six months in the refrigerator, half full and opened once a month, and still no evidence of yellowing.

    I have some D316 and Mocon in the refrigerator and freezer. The bottles of D316 are half full, and I've been opening them once a month for a few minutes to simulate typical hobbyist usage. It's been six months, and there's still no evidence of yellowing (oxidation) visible in a glass eyedropper. For comparison, when stored at room temperature and *not* opened, these glycol-based ascorbate concentrates start yellowing after 2-3 months. Evidently, they like to be kept cold.

    Mark Overton

  10. #550
    sun of sand's Avatar
    Join Date
    Feb 2007
    Shooter
    4x5 Format
    Posts
    600
    Images
    10
    Quote Originally Posted by albada View Post
    I'm not sure where frame 24 is. Could you give the posting number? It's in the upper-right corner of the posting. For example, this is posting #521.

    BTW, having XTOL last 4 years is amazing. You mention keeping it chilled: Do you have issues with precipitate collecting at the bottom of the bottle? When I tried refrigerating my XTOL, I quickly got some precipitation.

    Mark Overton
    I used some of my 5L xtol recently at 1:1 to develop 3 films
    assorted
    plus-x
    tri-x
    arista something
    shot as much as 3 years ago ..maybe longer

    developed for 9 minutes to compensate for the age of film
    the label on the bigger untouched bottle was actually Nov 9 2007 ...not 2009
    this was on a large maybe 1/2 gallon brown glass Bud bottle with plastic press fit cap

    bottle I used was a 40oz bottle half full. I would reuse the developer stock and that bottle had been opened/used since I mixed it ..maybe late 2008 at latest

    My basement stays 43-45 in winter and never above 65 in summer
    the concrete floor must be colder
    precipitate? I don't know if there is any sedimentation at the bottom
    there are some "floaters" in the 1/2 used xtol. I didn't even filter it as it was unimportant film
    My dektol will settle out upon standing which then needs a shake
    Don't believe I've noticed this with xtol but i don't shake it and probably haven't held the bottle up to light

    I'll pour it out and take some photos one day


    still
    late 2007 half used/reused bottle still develops film 1:1 in 9 minutes
    going on 7 years

    whether it's 100% or 91.4% i can't tell you
    It is a clearish yellow in color
    I remember the fresh mixed xtol being an off white color
    milky perhaps

    but I haven't mixed any since then. I don't use xtol anymore



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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