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Ink Filler!

  1. Nov 19, 2008 #1
    Basic question - How does an rubber ink filler work?
    (I don't want answers like - there is a vacuum created thus ink fills space and thus... Thats not Physics)

    Extending discussion : Is it better to press the rubber then dip and then suck and remove. OR
    To dip then press and suck and remove?
     
  2. jcsd
  3. Nov 19, 2008 #2

    Danger

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    What the hey is a rubber ink filler? :confused:
    Is it something like a syringe or turkey baster or likewise that vacuums up a liquid from one location to deposit it in another?
    If so, it's better from a practical standpoint to press first. When you press with the tip under the surface, you risk blasting some of the fluid out of the container with air pressure.
     
  4. Nov 19, 2008 #3
    Of course it's physics... what else would it be? If you don't want answers involving vacuums, pressures and so forth then I have no idea how it could be answered.
     
  5. Nov 19, 2008 #4
    Danger, this might be in reference to "after-the-market" printer ink refill-kits. Not sure. But in any event your comment that the syringe should be expelled of all air prior to insertion and suctioning is, of course, very correct.
     
  6. Nov 20, 2008 #5
    ofcourse! i meant lets have a detailed explanation of the physics behind it.
     
  7. Nov 20, 2008 #6

    HallsofIvy

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    You said "(I don't want answers like - there is a vacuum created thus ink fills space and thus... Thats not Physics)" . What part of that is NOT physics?

    I would have answered that pressing the "trigger" on the fountain pen presses air and ink out of the rubber reservoir. Once you release it, the air pressure on the top of the ink bottle pushes ink back into the reservoir.

    But that's exactly what you have pronounced to be "not Physics"!
     
  8. Nov 20, 2008 #7

    Danger

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    I never even thought of a fountain pen; haven't seen one in decades. I didn't know that they still made them. When we started using ink pens instead of pencils in school, they had been replaced by the cartridge type. That was in '65 or so.
     
  9. Nov 21, 2008 #8
    Do you think that's a real satisfactory explanation?!? Why not try a quantitative analysis? Let the ink filler be of length 'L' and let us dip it such that the rubber just stays out of the ink. So the tip of the filler is at a depth 'L'. Let us now assume that we have dipped it normally, i.e., we have not pressed the rubber. The current situation is similar to holding a tube inside the liquid with one end closed. I am not sure about that! I don't know if you can consider it closed as there is a column of air over it. I think you can!
     
  10. Nov 21, 2008 #9

    Danger

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    Sorry, man, but it seems to me that you're trying to explain bowling by quantum principles.
    It's simple. When the bulb is compressed, it has zero internal volume and therefore zero interior pressure. You immerse it in the liquid and release the bulb. That lets the air pressure impinging upon the fluid to force it into the expanding volume of the bulb to equalize the pressure. (In an ideal situation, of course; in reality you won't get zero volume.)
     
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