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Magnitism or Static Electricity Help please.

  1. Jun 13, 2009 #1
    Hello All,

    There is this machine that allows one to dropped glitter onto multiple plastic objects and the glitter cling / stuck onto the plastic while excess fell through a wire grid that the objects were sitting on. The glitter then would be sucked up by a vaccum and re-dropped onto the objects.

    My question is how did they make the glitter cling / stuck on?

    My first thought was that it had to do with magnets but can a magnet attract glitter onto plastic.. and on multiple pieces spread out - even if it's on a grid?

    My second thought was that the glitter was static charged and just clung onto the first thing it touched- now how would you make multiple objects magnetic - or - statically charge glitter?

    I would like to replicate this event on a larger scale for my business.

    Any advise or comments would be appreciated as i am completely stumpped on how they did it.

    Thanks!
     
  2. jcsd
  3. Jun 13, 2009 #2
    I'd imagine that static electricity is at work here. When cars are painted, the paint droplets are sprayed through an electrostatic field. The droplets acquire charge with respect to the surface of the car, and tend to land evenly across the surface. This allows an even finish on the car, without using excess paint.

    Here is a good link I found that might help:
    http://www.spraytec.com/electrostatic-spraying [Broken]
    Note that the word magnetic is used in this article to describe the attraction between the paint and the surface. In simple terms, electrostatic forces are at work.
     
    Last edited by a moderator: May 4, 2017
  4. Jun 13, 2009 #3
    Thank you BAnders1! Perfect Answer i was looking for.

    How my next question would be how to make a electrostatic field for the glitter?..
     
    Last edited by a moderator: May 4, 2017
  5. Jun 13, 2009 #4
    From what I understand, the supply reservoir for the paint (or glitter, in this case) is held at high voltage, while the surface to be coated is grounded.

    I cannot find a means by which the paint is actually charged, every article I come across just mentions that "the particles of paint are given an electric charge." This question seems best fitting for an engineer, and since I am a physicist, much of what I know is hypothetical and idealized.
     
    Last edited: Jun 13, 2009
  6. Jun 13, 2009 #5
    Hi, inkjet photocopiers work exactly on the same principle, i believe in your case the plastic container is charged thus attracting the glitter, im a bit new to website linking so i write the link, i found a good info on 'How it works' website if you look up photocopier, it may give you the insite you need
     
  7. Jun 13, 2009 #6
    You need to send the glitter through a weak corona discharge. For example, send the glitter between two parallel screens where one is grounded and the other is at a voltage adjusted so that there is a very slight corona but not nearly high enough to cause an arc. This is a little touchy if humidity varies a lot. Its roughly the same thing as a bug zapper only a bit higher voltage (bug zappers are adjusted ~below~ the voltage that produces a corona, just to make sure they don't arc in high humidity or if the screens are a little bent too much). In fact you might experiment with a bug zapper, although if the glitter pieces are too large then they will cause an arc.

    Also, if the target object is nonmetallic, you'll want AC instead of DC on the screens so that you get a mixure of positively and negatively-charged glitter, so that the target surface charge stays near neutral. otherwise it would gain a charge until it started repelling the same-charged glitter. Bug zappers are AC (not DC). Although those hand-held battery operated zappers ARE DC.

    Another consideration is sharp points on the screens. devices that charge ink toner are often very furry-looking--those points help the corona stay stable without arcing.
     
    Last edited: Jun 14, 2009
  8. Jun 13, 2009 #7
    You can use a 'negative ion generator'---the type used to remove smoke/odor from the air.

    The paint or glitter would be blown over the points releasing the negative charges. The other electrical connection would go to the metal to be painted, or to a piece of metal placed behind the plastic object to be 'glittered'.

    A hobby air-gun paint blower can be used.

    Mostly, you would want to use colored powder instead of paint. Then the object needs to be heated to melt the colored plastic onto the metal object. A toaster oven can be used. DO NOT use the oven afterwards for food! (In other words, go to a thrift shop and pick up a used one.)

    Do a 'Google' on powder coating to find some details.


    Neil
     
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