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  1. #21
    olleorama's Avatar
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    Seriously people, mercury vapour for the sake of developing film? I'd rather go digital! Mercury is nasty stuff. Specially considering it's potential benefit in this case.

  2. #22
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    Looking forward to it Alvaro.
    If you are the big tree, we are the small axe

  3. #23

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    I'm also looking forward to it, but in the meantime I found this video that shows the mercury evaporating at room temperature. It does say the beaker has been warmed by hands though.

  4. #24
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    Mercury does indeed vaporize at room temperature. Check out this health and safety vid: http://www.mwsi.com/new/videos/Mercury.mpg

    The ultraviolet light is needed to visually see it, since the vapor is to...ummm...'thin' to see with the naked eye (don't know a better term).

    I surely wouldn't do this since exposure to mercury is so incredibly damaging to the human nervous system. That said, film speed increases can be done with ammonia or peroxide since all you're trying to do is super-saturate the film emulsion with oxygen to help speed up the halide reactions. There's an old astrophotography book somewhere on my shelf that speaks of doing this when the old BW emulsions were still very slow and they needed the increase.
    K.S. Klain

  5. #25
    holmburgers's Avatar
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    This thread isn't really about mercury sensitization, that was just a tangent. It's just about pushing Provia 400 to 1600. I would bet that Alvaro here did nothing with mercury.
    If you are the big tree, we are the small axe

  6. #26

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    Now back onto mercury As any other material in liquid state it of course vaporizes even when far from boiling point. The warmer the faster though.

  7. #27
    Athiril's Avatar
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    So do some solids.

  8. #28

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    Quote Originally Posted by Athiril View Post
    So do some solids.
    True, but as far as I know only when at given temperature and pressure there is direct transition from solid state to gas state.

  9. #29
    Athiril's Avatar
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    Many do it at room temp in open air.

  10. #30

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    Quote Originally Posted by Athiril View Post
    Many do it at room temp in open air.
    Indeed - because for those these are the right conditions. For example is you put frozen C02 in room conditions it does not melt first and than evaporate - it sublimates, because liquid state of C02 only exists at pressures 5 times the normal pressure (at give temperature range only of course).

    Don't we all love Wikipedia

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