Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,705   Posts: 1,548,478   Online: 841
      
Page 5 of 6 FirstFirst 123456 LastLast
Results 41 to 50 of 54
  1. #41

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    3,865
    Here are some oxygen permeability data from the following website http://www.ucc.ie/fcis/PKplastics.htm

    The larger the value the greater the oxygen transfer rate.

    LDPE 7900 > HDPE 2900 > PVC 120 > PET 95 (units cm3/m2.24h.atm)

    The difference between the two polyethylenes and PET and PVC is striking.
    Last edited by Gerald C Koch; 09-15-2012 at 12:09 AM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  2. #42
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    14,300
    Images
    302

    For Accordion Bottle Users

    Quote Originally Posted by Gerald C Koch View Post
    Here are some oxygen permeability data from the following website http://www.ucc.ie/fcis/PKplastics.htm

    The larger the value the greater the oxygen transfer rate.

    LDPE 7900 > HDPE 2900 > PVC 120 > PET 95 (units cm3/m2.24h.atm)

    The difference between the two polyethylenes and PET and PVC is striking.
    I understand the theory, and I thank you for posting it. What it doesn't explain is why the accordion bottles still work fine.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  3. #43
    markbarendt's Avatar
    Join Date
    May 2008
    Location
    Ignacio, CO, USA
    Shooter
    Multi Format
    Posts
    5,757
    Blog Entries
    3
    Images
    19
    Quote Originally Posted by Thomas Bertilsson View Post
    I understand the theory, and I thank you for posting it. What it doesn't explain is why the accordion bottles still work fine.
    There are various anecdotal ways the following truism has been said, the exact numbers don't matter, the concept is born out in my experience.

    "Perfection is illusive and expensive, every half step toward perfect requires double the effort of the previous step. The first 50% of quality is possible with limited attention and effort, the next 25% takes twice that effort, and so on."

    So as a possible example in the case of the accorian bottles the first 50% is available just by putting it in a bottle (any bottle rather than staying in a tray), squeezing out the air may get us to 75% of perfect, keeping it away from heat might get us to 87.5% of perfect.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  4. #44
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    14,300
    Images
    302
    That's very well written, Mark.

    I guess what I'm trying to say is that if Xtol is given 6-12 months as 'life span' by Kodak after it's mixed, and if properly stored, I'm getting 100%, because after 6-12 months in accordion bottles I see no difference.

    So it raises the question of what level of importance should be given to storing your liquid concentrates and working solutions in vessels that have better characteristics than accordion bottles.

    I don't like 'convention' and assumptions. I like to see for myself by doing. Empirical evidence outweighs theory, in my opinion.


    Quote Originally Posted by markbarendt View Post
    There are various anecdotal ways the following truism has been said, the exact numbers don't matter, the concept is born out in my experience.

    "Perfection is illusive and expensive, every half step toward perfect requires double the effort of the previous step. The first 50% of quality is possible with limited attention and effort, the next 25% takes twice that effort, and so on."

    So as a possible example in the case of the accorian bottles the first 50% is available just by putting it in a bottle (any bottle rather than staying in a tray), squeezing out the air may get us to 75% of perfect, keeping it away from heat might get us to 87.5% of perfect.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  5. #45
    BradS's Avatar
    Join Date
    Sep 2004
    Location
    S.F. Bay Area, California
    Shooter
    Large Format
    Posts
    4,059
    Images
    1
    Theory and evidence go together. Either one absent the other is pretty useless.

  6. #46
    BradS's Avatar
    Join Date
    Sep 2004
    Location
    S.F. Bay Area, California
    Shooter
    Large Format
    Posts
    4,059
    Images
    1
    And while were addressing the insanity of photgraphers...lets examine the film in the freezer paradigm....talk about going after the last few percent...

  7. #47
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    14,300
    Images
    302
    Quote Originally Posted by BradS View Post
    Theory and evidence go together. Either one absent the other is pretty useless.
    Perhaps I misunderstand. Not sure what you're saying, but ponder this: If theory is assumed correct, but there is no empirical evidence to back it up, I agree that the theory was not directly helpful. (Indirectly the theory can still be useful. It isn't possible to prove every theory correct [theorem?]). Conversely, however, if practice and use reveals that something works, why does it matter what the theory says? That part does not make sense to me. If it works, it works!
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  8. #48
    BradS's Avatar
    Join Date
    Sep 2004
    Location
    S.F. Bay Area, California
    Shooter
    Large Format
    Posts
    4,059
    Images
    1
    there is a theory or, more properly, a hypothesis behind the "if it work, it works" approach. Namely, the implicit assumption, or hypothesis is that it works. Your empirical evidence does not contradict the (implicit) hypothesis and so, you accept your hypothesis as a working theory.

    I started with the same hypothesis but, my empirical evidence contradicted the "it works" hypothesis so, I am forced to reject the hypothesis.
    Last edited by BradS; 09-18-2012 at 04:05 PM. Click to view previous post history. Reason: Spelling.

  9. #49
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    14,300
    Images
    302
    Quote Originally Posted by BradS View Post
    there is a theory or, more properly, a hypothesis behind the "if it work, it works" approach. Namely, the implicit assumption, or hypothesis is that it works. Your empirical evidence does not contradict the (implicit) hypothesis and so, you accept your hypothesis as a working theory.

    I started with the same hypothesis but, my empirical evidence contradicted the "it works" hypothesis so, I am forced to reject the hypothesis.
    Well, I assume that if somebody sells a container to be used for chemical storage that it is capable of storing chemicals. It does that quite well, without fault as far as I'm concerned.

    There are many theories to why the accordion bottle may or may not work. Material, construction, thickness, ability to purge oxidizing air, cap seal, light filtration, response to heat and humidity, chemical resistance... Many factors can affect how the bottle will work. Should I form a hypothesis for each and every one of those, and then debate within or do research to figure out whether I think it will work? Or should I just go ahead and use it? You're making it too complicated to buy a bottle to store chemicals in, Brad... I don't want my brain to hurt. I want it to have a good time.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  10. #50
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,238
    Quote Originally Posted by alexmacphee View Post
    This article may be of interest :-

    http://www.udmercy.edu/crna/agm/phenvitc.htm

    I no longer use accordion/concertina bottles.
    I don't see where they tested the accordion bottles on that article.

Page 5 of 6 FirstFirst 123456 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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