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  1. #1
    Ian Grant's Avatar
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    Modern Rodinal Substitutes Part II

    Apologies for having to start a new thread but I can't read or even access the first to reply to posts.

    So with a bit of telepathy

    Quote Originally Posted by Kirk Keyes View Post
    Well, there's a problem there, as it's really hard to measure pH accurately when it gets much above 12.5 or so. You have to start getting special electrodes and the like.

    But for MSDS work, it doesn't have to be too precise.
    __________________
    Kirk

    A point that's being missed is that A&O give a figure of 2.7% Potassium Hydroxide not 3% in older Agfa MSDS.

    The pH is around 14 sure, but the actual requirement is the pH of the working dilute solution rather than the concentrate which is given elsewhere as pH 11.55, which I commented on in the first post of the thread.

    Way back Ron (PE) mentioned adjustments to Rodinal before bottling, the question we need to ask is are they adjusting on the basis of the concentrate, or also doing some tests on a dilute sample, as this will be a far more accurate indicator.

    Can someone please post a link to this continuation on the original post.

    Ian

  2. #141

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    Please respond here! The other thread is harder to find!
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  3. #142

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    Quote Originally Posted by Ray Rogers View Post
    Kirk,
    How can I Calculate -log10 [whatever] on line?
    I no longer have a scientific calculator...

    Thanks

    Ray
    ---------
    ps, Sorry for the location of ths post... it should be in part 2 very confused... sorry ...

    Ray - I would go to http://download.openoffice.org/ and download OpenOffice. It has an spreadsheet program like Excel called "Calc" along with other MS Office like programs. If you can't afford or don't want to spend the money on MS OFfice, then OpenOffice from Sun is a great alternative.

    Then you can calculate negative logs to your heart's content!

    Also, if you're a Windows person, search around for Microsoft's scientific calculator for windows - under accessories under programs under the start button. It has a scientific mode. I'm sure Mac/linux has something you can download as well.
    Last edited by Kirk Keyes; 09-04-2009 at 10:50 AM. Click to view previous post history.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  4. #143

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    Quote Originally Posted by Kirk Keyes View Post
    Ray - I would go to http://download.openoffice.org/ and download OpenOffice. It has an spreadsheet program like Excel called "Calc" along with other MS Office like programs. If you can't afford or don't want to spend the money on MS OFfice, then OpenOffice from Sun is a great alternative.

    Then you can calculate negative logs to your heart's content!

    Also, if you're a Windows person, search around for Microsoft's scientific calculator for windows - under accessories under programs under the start button. It has a scientific mode. I'm sure Mac/linux has something you can download as well.
    I have office on an OLD old mac...
    Open Office is on this computer I am using now...
    but I have not really used it.

    The MS scientific calculator you are talkng about...
    is that a freeware or payware item?

    Ray

  5. #144
    BradS's Avatar
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    even easier...try numcalc

    http://www.numcalc.com/

    There's nothing to download. it is a website that acts like a scientific calculator.

  6. #145
    Dave Pritchard's Avatar
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    Quote Originally Posted by Ray Rogers View Post
    I have office on an OLD old mac...
    Open Office is on this computer I am using now...
    but I have not really used it.

    The MS scientific calculator you are talkng about...
    is that a freeware or payware item?

    Ray
    It's the normal Windows calculator. Look for a menu pick to switch between normal mode and scientific mode.

  7. #146

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    Quote Originally Posted by Dave Pritchard View Post
    It's the normal Windows calculator. Look for a menu pick to switch between normal mode and scientific mode.


    You mean that button that says "log" ?



    Problem solved!

    I must have been thinking about antilogs or something...
    I remember not being able to do it quite so easily....

    Ray

  8. #147
    gainer's Avatar
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    -log(x) = log(1/x).
    I have a TI-30XIIS pocket calculator that does log and trig functions and a lot more. It cost less than $30 and can be found at stationery and office supply places, Rite Aid pharmacies and ordered over the internet. It gets power from light. If there's enough light to see it, it runs.
    Gadget Gainer

  9. #148

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    Quote Originally Posted by gainer View Post
    It gets power from light. If there's enough light to see it, it runs.
    I used to have 3 calculators I used in my DarkLab... one was solar powered but it lost data unless I was quite close to a safelight...


    My old programable calculator did not read properly unless you squezed it in just the right spot. Missing decimals were always fun...
    but i just couldn't throw it away.


    I guess I do need a good new one!

    The last couple were bought from 1$ stores; and they don't come with a whole lot of skills!


    ray

  10. #149

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    Quote Originally Posted by Ray Rogers View Post
    but i just couldn't throw it away.
    I have a Rockwell scientific that I got in 1977 in jr. high school. I replaced it with a Texas Instruments TI-58 programmable in high school, which I replaced with the first graphing calculator (a Sharp) in 1987 when I started working in a laboratory. Then I got a TI-82 about 1995, and it's had some hard lab working since then. It's starting to get some stuck pixels, which sucks as it affects all the digits on a particular line.

    So I'm thinking of getting a new one too... But I have all of the old ones still!
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  11. #150
    gainer's Avatar
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    Does anyone know if, and if so where, I can buy the n-methyl paraminophenol base of Metol without the H2SO4 tail?
    Gadget Gainer



 

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