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RE: [PPLetterpress] Aging plates?

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  • Joel Benson
    Hi Ed, Sorry for the slow reply here- yes, they are called Blacklights on the bulbs, but they aren t purple-looking like the incandescent blacklights. They
    Message 1 of 26 , May 14, 2002
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      Hi Ed,

      Sorry for the slow reply here- yes, they are called "Blacklights" on the bulbs, but they aren't purple-looking like the incandescent blacklights. They cost me about $15 each, I think. I'll look at the product numbers when I get home- though I think it is a pretty standard Phillips bulb. I use about a 4 minute exposure time for fine type, 30 to 45 seconds for big solids or halftone screens.

      I don't think it is the wattage that makes the difference so much as the specific wavelength of UV that the bulb gives off. I think the lamps you are using probably emit a large amount of light at one end of the UV spectrum and a lesser amount at the other end, which happens to be the end that the polymer is sensitive to. I remember a discussion of this with details about the wavelengths on either this list or LETPRESS, but I don't have it saved anywhere.

      It sounds like there is a lot of leeway in exactly how far the bulbs need to be from the plate material. Silver May Kitten has the bulbs a foot away, Brian Allen has his 1.5-2" away and much closer together. That seems to define a range of acceptability. Using a Stouffer scale would tell you how long your exposure needs to be for whatever set up you construct.

      Joel

      Joel Benson
      Dependable Letterpress
      San Francisco

      -----Original Message-----
      From: Ed Inman [mailto:edinman@...]
      Sent: Monday, May 13, 2002 5:15 PM
      To: PPLetterpress@yahoogroups.com
      Subject: Re: [PPLetterpress] Aging plates?


      You expose polymer with 40 Watt lamps? What exposure times do you use with
      this setup, Joel? Are you referring to regular purple looking
      "blacklights?" I didn't think such a low wattage setup would work very well
      even with hours of exposure. Can you give us a product descritption as
      printed on the bulbs you use and a little more detail as to your process?

      For what it's worth my cheapo homemade lamp setup is just a Sylvania "Sun
      Gun" that uses a 650 watt "DWY" halogen photo optic lamp. The lamps come
      with a warning that the bulb emits UV radiation and that you should not look
      directly into the fixture. You can usually find these used on ebay for $10
      to $15 and they will expose polymer very nicely in about 30 minutes time
      from about four feet back. I think both the original Sylvania Sun Gun and
      the Sun Gun 2 both use the same DWY lamp.

      Ed

      Joel wrote:
      >>> The UV bulbs can go into standard flourescent fixtures. The unit I have
      has four standard, 24", straight-from-the-hardware-store, two-bulb fixtures
      mounted in it and wired up so they all come on together. I think the bulbs
      are 40W.<<<




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    • David Goodrich
      Vivian, You are wise in inquiring before trying the Morgan Expansion Trucks. I tried some on my Columbian No 2 and found there was not enough space for them.
      Message 2 of 26 , May 18, 2002
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        Vivian,
        You are wise in inquiring before trying the Morgan Expansion Trucks. I
        tried some on my Columbian No 2 and found there was not enough space for
        them.
        I suggest you contact Fritz Klinke at NA Graphics, who stocks them. He
        can be reached at nagraph@.... He can probably tell you whether or
        not they will fit. If they fit, they will solve your problem.
        You also might want to post an inquiry to the Letpress Discussion Group.
        I suspect more of their people use platen presses than the PPL group.

        Sorry not to have responded sooner. I have been away the past week.

        David

        -----Original Message-----
        From: 9 Spotmonk Design [mailto:vivian@...]
        Sent: Sunday, May 12, 2002 12:57 PM
        To: PPLetterpress@yahoogroups.com
        Subject: [PPLetterpress] Expandable Trucks


        Hi Everyone,

        I'm new to the PPLetpress List.

        I have a Craftsman 6 x 10 and was wondering if anyone has experience
        with using/converting expandable trucks. Two main problems at hand: I
        need to lower the the noise the press makes when the rollers leave
        the rail and move to the inking plate and back; and my rollers are
        about 1/8 inch (the circumference) larger than my trucks. What I'm
        doing now is putting a piece of pressboard behind the chase but don't
        know if this is a good long term solution.

        Thanks in advance for your responses.

        Vivian



        Vivian Leung
        9 Spotmonk Design
        vivian@...
        T 201 795 1668
        C 201 925 3168

        <http://www.9spotmonk.com>


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