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  1. #11
    gainer's Avatar
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    Things I should have learned in school but didn't.

    When you want to prepare a solution of a certain pH is it best to titrate with an indicator or a meter or some other means? How accurately should we know the pH of a developer solution. I have a feeling that test strips would be sufficient for most of our needs, but our wants are something else. I know that in research work one is often trying to determine the efect of changes in pH on something or the effect of changes in something on pH. One might like to know for example whether a production line has to use reagent grade of some ingredient or if a lower grade would suffice.

    From experience, I know that due to the logarithmic scales on most of our darkroom work there is a fair tolerance in the linear measures of weight and volume. How else could Crawley, for one, concoct a developer with measurements in nice round numbers and then proclaim it optimized for this or that? (I'm poking fun. Of course we know all his developers are optimized.)

    I'm always curious about pH and other quantitative measures of qualitative things, but it's always after I've seen that they work or not. Right now, I'd rather spend the money, if I had it, on a good shutter for my 5x7 camera.
    Gadget Gainer

  2. #12

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    I am using a Hanna too. It's an inherity of the previous job

    Just take care of the electrode (which is valid in general for pH meters) and then you have a pretty good instrument.

  3. #13
    David A. Goldfarb's Avatar
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    I'm also using the Hannah Checker, and it seems reliable.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  4. #14
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    Quote Originally Posted by gainer View Post
    Things I should have learned in school but didn't.

    When you want to prepare a solution of a certain pH is it best to titrate with an indicator or a meter or some other means? How accurately should we know the pH of a developer solution. I have a feeling that test strips would be sufficient for most of our needs, but our wants are something else. I know that in research work one is often trying to determine the efect of changes in pH on something or the effect of changes in something on pH. One might like to know for example whether a production line has to use reagent grade of some ingredient or if a lower grade would suffice.

    From experience, I know that due to the logarithmic scales on most of our darkroom work there is a fair tolerance in the linear measures of weight and volume. How else could Crawley, for one, concoct a developer with measurements in nice round numbers and then proclaim it optimized for this or that? (I'm poking fun. Of course we know all his developers are optimized.)

    I'm always curious about pH and other quantitative measures of qualitative things, but it's always after I've seen that they work or not. Right now, I'd rather spend the money, if I had it, on a good shutter for my 5x7 camera.

    Patrick;

    There are known formulas that will allow you to calculate the exact mixtures of carbonate to bicarbonate to get a given pH. You usually mix those in the right proportions and then add a few drops of acid or base with a pH meter present, to tweak the final pH at the desired temperature.

    Remember, the ratios give the pH range and the total quantity adjusts the buffer capacity of a solution.

    Usually, photo solutions are adjusted to within 0.1 pH unit at 20 degrees C with greater tolerance allowed in most cases for Fix, Bleach or Blix solutions.

    PE

  5. #15
    lee
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    I have a couple of Hanna PH Meters that were given to me by my ex-boss. Mine sorta eat batteries.

    lee\c

  6. #16

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    Quote Originally Posted by DarkroomExperimente View Post
    I've been having a lot of fun experimenting with homemade developers.
    I think it's time for a bit more precision....so I'm considering getting
    a pH meter. Any suggestions of what type to get...and from where?
    I've a Milwaukee SM 102 ph meter with temperature probe.
    Replaceable probe, two point calibration, automatic temperature
    compensation, +/- .01. www.milwaukeetesters.com
    About $100. Dan

  7. #17

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    thanks...

    I think I'm going to just get some litmus paper strips to start since I'm doing pretty basic experiments for now...and I'll upgrade to a "real" meter when I get into more serious stuff

  8. #18
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    Remember that litmus paper strips are hard to read under safelights.

    PE

  9. #19

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    Quote Originally Posted by DarkroomExperimente View Post
    I think I'm going to just get some litmus paper strips to start
    since I'm doing pretty basic experiments for now...
    In that case from Google enter, microessential lab .
    They have any of a few ways to check ph, water hardness,
    hypo silver levels, and ... Narrow range papers may be all
    you need. Paper and other means. Only $5 S&H. Dan

  10. #20

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    OK, looking at all the different Hanna meters is going to make my head explode

    IIRC they all seem to have automatic temperature compensation...

    I can't tell if the meters are shipped with calibration solutions...or if I need to get that too


    here is a selection of Hanna meters:

    http://www.caprockdev.com/pHmeters.htm


    here is a simple Hanna meter not shown on the caprockdev.com page:

    https://www2.carolina.com/webapp/wcs...y_rn=&crumbs=n

    I don't need anything fancy, it's just time to advance out of the stone age

    any pearls of wisdom out there?

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