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Raul Santillan

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Is possible replace solar light (UV) by a artificial source?

As you know, solar UV light is a natural bleach for cloths, bleaching effect depends on day conditions but even rainy sun´s UV rays are always present.
So in order to replace sun with an artificial source I wonder if some one can help me on develop this artifical source for bleaching cloths.

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  • Nov 15 2012: Yup, the "black lights" you sometimes see in clubs are UV lamps.
    • Nov 15 2012: great, do you know what characteristics I must to use for getting good results?; I mean

      Power = ?
      wavelenght = ?
      others = ?
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        Nov 15 2012: Anything that emits light with a wavelength less than 400nm is what you're looking for. Examples: http://en.wikipedia.org/wiki/Black_light#Types_of_black_lights

        As for power, the sun puts out ~32W/m^2 of UV light, so that gives you a baseline for what to look for. Make sure to protect the area you are doing this in: UV lights not only put out a lot of heat, but can also damage your eyes with that much power!
        • Nov 15 2012: thank you very much, In fact I´m using a UV lamp of around 1 watt in order to avoid damage on my eyes, but I can´t get bleaching (main purpose) cloths, do you know if distance between lamp and garment is important?; or maybe exposure time?
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        Nov 16 2012: I don't think a 1W lamp will do much: it might use a watt of power, but will only make about 1/4 watt of UV light and most of that won't touch your target. You will either need to get a much bigger lamp or concentrate sunlight somehow. As a rough estimate; if you had a lamp in a box lined with aluminum foil (maybe 75% of the light hits the target) then a 40W UV bulb would be about the same as direct sunlight for a pair of jeans, but then you have a fire hazard since you have around 30W of heat going into the box.

        Since you want to do it faster than sunlight, you'll need to make and seal the box with a UV-absorbing material (like acrylic) for safety. Then you just need to design a cooling system to prevent fires and you can put a bunch of UV bulbs in there! If you would rather use sunlight, you could suspend the clothes with wire and make a parabolic reflector underneath out of aluminum foil and scrap, but it's hard to estimate how effective those are when hand-made.

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