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  1. #11
    Worker 11811's Avatar
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    They taught that to us in eighth grade chemistry class. That was back in the days when they still taught actual chemistry in schools.

    While all the other kids were mixing alcohol and water together to learn about measuring volumes, I was mixing ammonia with iodine crystals and making the teacher's desk explode.

    Gee... Maybe that's the reason they don't teach chemistry anymore?
    Randy S.

    In girum imus nocte et consumimur igni.

    -----

    http://www.flickr.com/photos/randystankey/

  2. #12
    Vaughn's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    You guys ever hear of density?

    Whenever you mix up a solution of ANYTHING, the density changes from 1.0 (water at 20 deg C roughly) to something else that may be lower or greater than 1.0. That is why in exact photographic work, we measure things by weight or use solutions made to a volumetric standard. In other words, you do not add 100 ml of water, you dilute to 100 ml with water, or you dilute to 100 g total with water, using whatever method applies.

    PE
    Thanks...that makes sense. But just about all the formulas I have read for cyanotypes instruct one to add (for example) 100ml of water, not add water to make 100ml of solution. Or as in Hershel's original formula, "Ammonio-citrate of iron -- 20 parts, water -- 100 parts" (as per an article on unblinkingeye.com).
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  3. #13
    Photo Engineer's Avatar
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    A formula is a formula especially if it works. Just expect to have uneven amounts of you do it the way you describe.

    If it works, use it but expect what is observed in the OP.

    PE

  4. #14
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    Quote Originally Posted by Photo Engineer View Post
    ... In other words, you do not add 100 ml of water, you dilute to 100 ml with water, or you dilute to 100 g total with water, using whatever method applies.

    PE
    thanks - and that is what I do..... (dilute to)

    I think I might be even worse in explaining than in doing....

  5. #15
    gandolfi's Avatar
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    Quote Originally Posted by Worker 11811 View Post
    Are you measuring solutions in two separate beakers and pouring them together into a third or are you measuring 100 ml. of the first solution into a beaker then filling with the second solution up to 200 ml.?

    Try this experiment: Get some 90% isopropyl alcohol (from the drug store) and measure 50 ml. into a beaker or graduate. Next, using a second container, measure out 50 ml. of plain water. Pour them together. Note the volume of the combined solutions.

    You would expect the volume to be 100 ml. but it's not. It will be less.

    The reason is because the molecules of water and alcohol are different sized. The molecules of alcohol slip into the spaces between the water molecules. It's similar to what would happen if you poured a bucket full of sand into a bucket full of marbles. The total volume will be less because the sand is going between the marbles.

    The answer would be to measure two solutions separately and pour them together into a third container.
    Randy - what I will do is to mix 1:1 in plain daylight and see if it makes 2.....

  6. #16

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    C'mon guys, it's the ferri snatchers. Everybody knows that!

  7. #17
    Vaughn's Avatar
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    Does mold growth in the Ferric Amm citrate add to the volume?...LOL!
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  8. #18

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    Vaughn,
    You are a Carbon Transfer Man. What are you doing messing around with cyanotypes? Is this a signe of encroaching senility? Its like Beethoven playing "Chopsticks" on the Kazoo.
    Bill

  9. #19
    Vaughn's Avatar
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    Hey, Bill! Got to get the kids hooked, I mean, interested in alt processes with the easy stuff -- then hit the arteries with the harder stuff later!

    Taken during a two-week session with high school students. The first week was making pinhole cameras (empty 250 sheet boxes of 8x10 photo-paper and using 8x10 litho film) and cyanotypes -- and the second week was 35mm film and silver gelatin prints.
    Attached Thumbnails Attached Thumbnails Self portrait.jpg  
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

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