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Toyobo KM152 exposure

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  • hersomwally
    Somewhat related to my last post- Eric and Gerold said that an exposure of 18 on the Stouffer scale seemed high for KM152. This is another question I have been
    Message 1 of 7 , Apr 17 12:06 PM
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      Somewhat related to my last post- Eric and Gerold said that an exposure of 18 on the Stouffer scale seemed high for KM152.

      This is another question I have been wanting to ask. The "tips for printight" says it should be 15/16 for KM152 but when I tried that I got almost no shoulders at all and fine line (.5pt) crop marks were undercut. Even when I expose to 18, the fine lines have very little shoulders and the ends of the lines have a very slight undercut.

      Is this normal for the toyobo material?

      I tried processing some Jet 152sb material and actually had the opposite problem- the shoulders were too broad and I had to bring the exposure down.

      We do a lot of fine reverses so I don't want to overexpose but I also want to have structural integrity on fine lines and dots.

      Is there anything else that could cause lack of shoulders/undercutting fine lines?

      Thanks!
      Wally
    • Gerald Lange
      Wally I m not sure what you are saying. If you are doing reverses how can you have a lack of shoulder or undercutting? Normally, solids do not require as much
      Message 2 of 7 , Apr 17 1:36 PM
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        Wally

        I'm not sure what you are saying. If you are doing reverses how can you
        have a lack of shoulder or undercutting?

        Normally, solids do not require as much exposure time as normal type. By
        increasing exposure time what you are actually doing is building up the
        relief. Halftones and fine lines, which do require more than normal
        exposure have very shallow reliefs.

        If you are exposing solids with reverses, by increasing the exposure,
        you are filling in the reverse.

        Gerald


        On 4/17/13 12:06 PM, hersomwally wrote:
        > Somewhat related to my last post- Eric and Gerold said that an exposure of 18 on the Stouffer scale seemed high for KM152.
        >
        > This is another question I have been wanting to ask. The "tips for printight" says it should be 15/16 for KM152 but when I tried that I got almost no shoulders at all and fine line (.5pt) crop marks were undercut. Even when I expose to 18, the fine lines have very little shoulders and the ends of the lines have a very slight undercut.
        >
        > Is this normal for the toyobo material?
        >
        > I tried processing some Jet 152sb material and actually had the opposite problem- the shoulders were too broad and I had to bring the exposure down.
        >
        > We do a lot of fine reverses so I don't want to overexpose but I also want to have structural integrity on fine lines and dots.
        >
        > Is there anything else that could cause lack of shoulders/undercutting fine lines?
        >
        > Thanks!
        > Wally
        >
        >
        >
        >
        > ------------------------------------
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
      • hersomwally
        Often I will have a solid with fine reverses and free standing fine type or lines on the same plate. So, I guess I need to find a middle ground exposure that
        Message 3 of 7 , Apr 17 2:08 PM
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          Often I will have a solid with fine reverses and free standing fine type or lines on the same plate. So, I guess I need to find a middle ground exposure that will work for both.

          What would be your normal exposure for KM152? or to put it another way, what do you think would be the minimum exposure to create enough shoulder to maintain structural integrity on free standing fine lines?


          --- In PPLetterpress@yahoogroups.com, Gerald Lange <Bieler@...> wrote:
          >
          > Wally
          >
          > I'm not sure what you are saying. If you are doing reverses how can you
          > have a lack of shoulder or undercutting?
          >
          > Normally, solids do not require as much exposure time as normal type. By
          > increasing exposure time what you are actually doing is building up the
          > relief. Halftones and fine lines, which do require more than normal
          > exposure have very shallow reliefs.
          >
          > If you are exposing solids with reverses, by increasing the exposure,
          > you are filling in the reverse.
          >
          > Gerald
          >
          >
          > On 4/17/13 12:06 PM, hersomwally wrote:
          > > Somewhat related to my last post- Eric and Gerold said that an exposure of 18 on the Stouffer scale seemed high for KM152.
          > >
          > > This is another question I have been wanting to ask. The "tips for printight" says it should be 15/16 for KM152 but when I tried that I got almost no shoulders at all and fine line (.5pt) crop marks were undercut. Even when I expose to 18, the fine lines have very little shoulders and the ends of the lines have a very slight undercut.
          > >
          > > Is this normal for the toyobo material?
          > >
          > > I tried processing some Jet 152sb material and actually had the opposite problem- the shoulders were too broad and I had to bring the exposure down.
          > >
          > > We do a lot of fine reverses so I don't want to overexpose but I also want to have structural integrity on fine lines and dots.
          > >
          > > Is there anything else that could cause lack of shoulders/undercutting fine lines?
          > >
          > > Thanks!
          > > Wally
          > >
          > >
          > >
          > >
          > > ------------------------------------
          > >
          > > Yahoo! Groups Links
          > >
          > >
          > >
          > >
          >
        • Eric
          ... I would give each different image type the specific exposure it needs by masking and making multiple exposures. It doesn t need pin registration, just
          Message 4 of 7 , Apr 17 4:11 PM
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            --- In PPLetterpress@yahoogroups.com, "hersomwally" <cwhersom@...> wrote:
            >
            > Often I will have a solid with fine reverses and free standing fine type or lines on the same plate. So, I guess I need to find a middle ground exposure that will work for both.


            I would give each different image type the specific exposure it needs by masking and making multiple exposures. It doesn't need pin registration, just place pieces of cardboard cut to size on top of the crene. If the only underexposed element in a given plate is the crop marks, try giving them a double exposure. Just watch out that when removing the masking material you are not leaving debris that will interfere with exposure.
            --Eric Holub, SF
          • hersomwally
            Wow! That s a great idea. I wouldn t have thought of that. I ll try that if I can t find a middle ground that will work. I still find it odd that even with
            Message 5 of 7 , Apr 17 5:24 PM
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              Wow! That's a great idea. I wouldn't have thought of that. I'll try that if I can't find a middle ground that will work.

              I still find it odd that even with an 18 exposure there isn't much shoulder on the crop marks. But then I guess I've never seen a "professionally" made plate from Toyobo, I've only seen the Jet ones that Boxcar makes.




              --- In PPLetterpress@yahoogroups.com, "Eric" <Megalonyx@...> wrote:
              >
              >
              >
              > --- In PPLetterpress@yahoogroups.com, "hersomwally" <cwhersom@> wrote:
              > >
              > > Often I will have a solid with fine reverses and free standing fine type or lines on the same plate. So, I guess I need to find a middle ground exposure that will work for both.
              >
              >
              > I would give each different image type the specific exposure it needs by masking and making multiple exposures. It doesn't need pin registration, just place pieces of cardboard cut to size on top of the crene. If the only underexposed element in a given plate is the crop marks, try giving them a double exposure. Just watch out that when removing the masking material you are not leaving debris that will interfere with exposure.
              > --Eric Holub, SF
              >
            • Gerald Lange
              Eric s comment is correct. This is the manner in which different elements SHOULD be exposed on one plate. This has been a common practice in the printing
              Message 6 of 7 , Apr 18 11:34 AM
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                Eric's comment is correct. This is the manner in which different elements SHOULD be exposed on one plate. This has been a common practice in the printing industries for many years (and long before photopolymer). I'd recommend the use of Rubylith (or Amberlith) masking film though rather than cardboard (to prevent UV leakage).

                Not many photopolymer plate processors will do this for the client anymore though and to some extent it is the client's fault. They want their plates as cheap as possible AND today.

                Gerald
                http://BielerPress.blogspot.com




                --- In PPLetterpress@yahoogroups.com, "Eric" <Megalonyx@...> wrote:
                >
                >
                >
                > --- In PPLetterpress@yahoogroups.com, "hersomwally" <cwhersom@> wrote:
                > >
                > > Often I will have a solid with fine reverses and free standing fine type or lines on the same plate. So, I guess I need to find a middle ground exposure that will work for both.
                >
                >
                > I would give each different image type the specific exposure it needs by masking and making multiple exposures. It doesn't need pin registration, just place pieces of cardboard cut to size on top of the crene. If the only underexposed element in a given plate is the crop marks, try giving them a double exposure. Just watch out that when removing the masking material you are not leaving debris that will interfere with exposure.
                > --Eric Holub, SF
                >
              • Eric
                ... The reason I suggested cardboard (I actually use scraps of binder s board) is that it won t curl up under the heat of the lamps like normal masking
                Message 7 of 7 , Apr 18 9:17 PM
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                  --- In PPLetterpress@yahoogroups.com, "Gerald Lange" <Bieler@...> wrote:
                  >
                  > . . . I'd recommend the use of Rubylith (or Amberlith) masking film though rather than cardboard (to prevent UV leakage).
                  >

                  The reason I suggested cardboard (I actually use scraps of binder's board) is that it won't curl up under the heat of the lamps like normal masking materials might when placed loosely over the crene. Maybe this is more of a concern for me since what little Rubylith and Amberlith I have left are coming off a roll and curled is its normal state.
                  --Eric Holub, SF
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