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UV Exposure Unit "Blueprints"?

topic posted Thu, January 25, 2007 - 11:18 AM by  Bill
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Howdy all!

I was looking through some old posts and saw someone say that had directions/blueprints on how to build your own UV exposure unit for developed photo emulsion. I've tried to get in touch with the person without much luck.

So, does anyone have any directions/plans/clue about where to look??

Thanks!
Bill
posted by:
Bill
Nashville
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  • Re: UV Exposure Unit "Blueprints"?

    Sun, January 28, 2007 - 4:54 PM
    Hello Bill:
    Mount 4 ultraviolet tubes in a wood box with 6 inch high walls. Put a glass rectangle above the light tubes(about 6 inches away). That's all there is ... easy and very effective. Let me know if you need more.
  • Re: UV Exposure Unit "Blueprints"?

    Sun, February 25, 2007 - 7:54 PM
    I posted this in another thread somewhere:

    I just made a home made exposure unit from stuff i bought around town. My exposure time is 6 min. I used 4 40 watt black light bulbs (Not black light Blue bulbs, like you see at some stoner's house.) These bulbs look just like regular fluorescent, but do not have the 'visible light' filterers that make black lights that deep violet color. I found them at a local lighting supply distributor. They cost about $11 each. You can find a fixture that holds 4 40 watt bulbs and includes the ballasts and light diffuser screen for $40 at Lowe's. Then I just built a box and stand, and put a piece of glass over it. You can get a piece of glass cut at any glass / window place. the dimensions i needed were 23 3/4" x 37 3/4" x 1/4" (the same as the outer dimensions of the fixture i bought). Then I just cut a cheap extension cord and wired it up with a light switch. It works great.
    • Re: UV Exposure Unit "Blueprints"?

      Mon, March 19, 2007 - 5:54 AM
      what did you use as lid? dont you have to keep it in a black room or something like that unless you use one of those vacuum lids?
      i am looking to build one but i need to finalize my drawings.
      • Re: UV Exposure Unit "Blueprints"?

        Fri, April 6, 2007 - 9:32 PM
        i actually put a thick blanket, flat piece of wood that's cut out to the size of the inside of the screen, and some heavy objects on top of the screen to act like a vacuum blanket. Having a thick blanket or a few towels over the image helps to apply pressure evenly over the image. It works great for me.
  • Re: UV Exposure Unit "Blueprints"?

    Tue, May 8, 2007 - 12:13 PM
    Bill, there are blueprints for making your own exposure unit at The Screenprint Store screenprintstore.com online. The problem with most homemade exposure units including the one touted in a previous post is that not all UV light is in the correct spectrum to properly expose screenprinting emulsion. You will need a bulb rich in the 330-430 Nanometer spectral range to expose emulsion. The best bulb will be a Metal Halide bulb, but still the Metal Halide bulb manufactured to expose emulsion is quite different from the Metal Halide bulb used to light a warehouse. Make sure that your bulb is in the correct spectral range in order to work properly.

    Also, a single point light source is always better than fluorescent lamps, which tend to scatter the light in all directions and produce undercutting of the image, which will destroy fine lines and other details. They also product soft images. They may, however, be fine for large images such as on signs and athletic lettering.

    Aquarium lights, ordinary fluorescent lamps, quartz halogen, tungsten, sodium vapor, mercury vapor are all weak in the required UV spectral range and are consider inappropriate for exposing emulson.

    Bill Hood
    School of Screenprinting
    schoolofscreenprinting.com

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