Electrophotography (Xerography)

Discussion in 'Alternative Processes' started by Joe VanCleave, Oct 21, 2006.

  1. Joe VanCleave

    Joe VanCleave Member

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    Just finished reading a biography of Chester Carlson, the inventor of Xerography, also known as Electro-photography (and not to be confused with Kurlian Photography).

    I was curious whether anyone else has considered recreating his early experiments, to wit:

    His initial experiments, done at home, involved a sulfur-coated zinc plate, electrostatically charged using a fur mitten. It was then exposed to a light pattern, then a special powder was sprinkled onto the plate, and the excess blown off. The remaining powder adhered to the plate in the negative pattern of the light image previously exposed to the plate (the sulfur layer acted to be slightly conductive upon exposure to light, discharging the electrostatic field only where light struck the plate). Since his powder did not have the properties of modern-day Xerox toner, he transfered the image to a sheet of wax paper by pressure, then heated the wax paper over a hot plate to fuse the image.

    Later experiments, leading to the "Ox box" manual Xerographic machine in the early 1950's by Haloid (the forerunner of Xerox Inc.), used amorphous selenium coated plates, which are much more light sensitive than sulfur is.

    Does anyone have any practical ideas on how to proceed with a home/darkroom recreation of this experiment? Obviously, it's fairly easy to get bottles of toner. Haloid's later experiments used a magnetic brush, composed of a mixture of iron filings with toner on a magnetic wand, to swipe across the charged plate; the toner stuck to the image charge on the plate, while the iron filing adhered to the magnet. This should be fairly easy to make.

    As I see it, the hard part is getting the selenium plate. Charging the plate could be via a small electrostatic generator, if rubbing fur by hand is insufficient.

    What I would like to see is an in-camera method of exposing the charged plate via a LF lens, then process the toner image onto fine art paper.

    Any suggestions are welcome (other than ... 'just use a copier'...).

    Joe
     
  2. htmlguru4242

    htmlguru4242 Member

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    I though of doing this awhile ago, but dismissed it as rediculous. It's good to know that I'm not insane :smile:.

    But that's a GREAT idea.

    Sure, using a copier would be easy, but where's the fun and adventure in that?

    You're (obviously) all set on the toner; that's available easily.

    But I wonder if the contast would be acceptable for in-camera use?

    I wonder if the sulfur plate would be easier to start out with? Sulfur is significantly easier to get than selenium, and probably cheaper.

    Hmm

    this has me thinking, I'm going to devise something in my head here; I'll get back to you when I do :-D
     
  3. Photo Engineer

    Photo Engineer Subscriber

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    Xerography can be done at most any contrast as long as the V LogE curve is adjusted accordingly. (V = Voltage and Log E is log Exposure) This makes curve shape adjustments in a manner similar to DLogE in film and paper.

    It can be done in color as well using colored toners. If you wish prints, the material to use is Titanium Dioxide. It, coated on conductive film makes a good reflection print material.

    I have seen superb B&W and Color prints done this way.

    PE
     
  4. htmlguru4242

    htmlguru4242 Member

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    Interesting to know that it's been done before!

    PE, do you have any suggestions as to how to go about this?
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    I have no idea. Sorry. I've seen it done at EK. It was called, internally, Electrocolor. There was quite a development project on this material in the 70s. I wish I could tell you more, but I only saw it done.

    PE
     
  6. htmlguru4242

    htmlguru4242 Member

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    I see. That's still neat though.

    What about your mention of Titanium Dioxide?
     
  7. Photo Engineer

    Photo Engineer Subscriber

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    Titanium Dioxide was coated on film or RC support. It is or can be made, light sensitive with appropriate sensitizers and can be used in the Xerographic process. Light plus a charge will deposit the dye or toner in the TiO2 leaving an image.

    The images I saw compared well with the Ektacolor Paper prints I saw by comparison in the 70s.

    PE
     
  8. avandesande

    avandesande Member

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    I have though about this is an interesting way to do digital... you would expose an electrostacilly charged plate, run it through some 'combs' and digitize the measured voltages.