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  1. #1

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    Mercury vapor light sources

    Hi folks

    I could do with a little advise on this. Today I ordered a 250 watt mercury bulb to be used in a conventional light fitting. My intention is to use it in a standard angle-poise desk lamp. I'll only be printing at a max of 10x8, usually 5x4, so thought this would be worth a go. However, I have a few questions on which I'd appreciate any help.
    • Does anyone know if this is going to produce enough UV for reasonable exposure times?
    • Am I going to set fire to the house by fitting a 250 watt bulb in a lamp designed to take about 60 watts? I will of course be using it only for short periods of time.
    • Can I use a normal conical reflector, or will this give uneven light coverage?
    • Is the idea to get the bulb as close to the printing plane without losing light at the corners or producing too much heat on the glass?

    Sorry for all the daft questions. I've been using the sun, but with winter on its way, I really want something a bit more predictable. Judging exposure by inspection just doesn't do it for me.

    Many thanks

    Geoff

  2. #2
    fotch's Avatar
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    I would not do this if I were you. You need a special fixture.

    See http://en.wikipedia.org/wiki/Mercury-vapor_lamp
    Items for sale or trade at www.Camera35.com

  3. #3

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    Thanks for the link Fotch.

    I probably should have said that this is a self ballasting bulb and is 'designed' to be used in a standard light fitting (or so I was told).

    It just seems a bit much to expect a bog-standard lamp to cope with it. Maybe it should have a heat-resistent fitting?

    It also seems a bit much to expect that a 10 quid bulb will give me a good light source. Well, I'll wait 'till it comes and see what it says in the info.

    Thanks again.

    Geoff

  4. #4

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    Quote Originally Posted by gwatson View Post
    Thanks for the link Fotch.

    I probably should have said that this is a self ballasting bulb and is 'designed' to be used in a standard light fitting (or so I was told).

    It just seems a bit much to expect a bog-standard lamp to cope with it. Maybe it should have a heat-resistent fitting?

    It also seems a bit much to expect that a 10 quid bulb will give me a good light source. Well, I'll wait 'till it comes and see what it says in the info.

    Thanks again.

    Geoff
    Some people are using 300 watt RD40 flood lights to expose AZO so I don't think 250 watts is too high for a conventional socket. However, your exposures will be fairly long and the bulb will generate a lot of heat.

    You might also consider a 27 or 30 watt BL spiral fluorescent, which will also go right into a conventional socket and does not require any ballast. Since virtually all of the light is useful UV exposure time may be as fast, or even faster, than with the 250 watt mercury bulb.

    Sandy King

  5. #5

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    Many thanks, Sandy.

    Since it's ordered and paid for, I'll test it and keep an eye on the heat generated. However, if it looks too good to be true,.... Having a young family, no money and even less time, the thought of just changing a bulb in a desk lamp was too strong a lure for me to resist. If an average exposure is more than 10 mins or so, it would not be worth it and I'll stump for a proper lighting system.

    The BL spiral Fluoro sounds interesting though. If you get the time, is the following link the kind of thing I should be looking for?

    http://www.bltdirect.co.uk/cat51_1.htm

    Thanks again, Sandy.

    Geoff

  6. #6

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    Hi Geoff,

    i have used the following and know a few other alt process workers use them with success too: http://cgi.ebay.co.uk/Philips-Facial...QQcmdZViewItem

    Hope this helps, Carl

  7. #7

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    Hi Carl

    This would be as convenient as changing a bulb (and I could tan those places the sun don't shine :-~. Sorry to conjure up grotesque images.

    Many thanks for researching the link. I'll dig a bit and update.

    Thanks again, Carl.

    Geoff



 

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