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Re: [PPLetterpress] platemaking issues

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  • Gary Mordhorst
    Hello Cody, The issue is that the offset plate maker has a pin point light system. This type of light will cause a letterpress plate to not have the shoulder,
    Message 1 of 22 , Mar 6 5:55 AM
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      Hello Cody,

      The issue is that the offset plate maker has a pin point light system. This type of light will cause a letterpress plate to not have the shoulder, which provides strength to the type form. A commercial photopolymer plate maker uses a bank of high UV bulbs, exposing the plate with a variety of angles of light. This diffused light source creates the shoulder on the type, and provides plate strength.

      You are going to find that small items, such as periods and dot on lower case "i"s drop off during the course of the press run.

      The light needs to be diffused, but I do not feel that there is any safe way to diffuse the NuArc's lamp.


      Best Regards,

      Gary Mordhorst
      AccuColor Plus, Inc.
      2134 W. Division
      Chicago, IL 60622

      www.accucolor.com

      (773) 227-7788


      Conventional Offset, Contemporary Letterpress, Foil Stamping

      AccuColor Plus is a Certified Adobe Print Service Provider




      ----- Original Message -----
      From: itsfancyletterpress
      To: PPLetterpress@yahoogroups.com
      Sent: Thursday, March 06, 2008 7:16 AM
      Subject: [PPLetterpress] platemaking issues


      I am super new to platemaking but things have gone smoothly except for one issue.

      The kreen went on easily. I created a framework to wrap it around and used the original
      hardware to affix the screen to the frame of my small Nuarc fliptop platemaker. I am hand
      washing out the plates and outside of the time spent with the nylon brush it is not too
      difficult.

      I have had fun exposing small sample pieces and recording the exposure times so I know
      what to expect from the platemaker.

      The problem is on all of my plates the side walls of the letters are at a 90 degree angle to the
      letters top surface. The ones I purchase have an angled slope.

      My question is how do I get my plate to taper more? I am using a Jet plate 152 and a boxcar
      deep relief base on my C&P's. I would love to get this problem fixed tonight because I hae
      spent a large fortune overthe years purchasing finished plates from vendors.

      cody
      It's Fancy Letterpress Studio





      [Non-text portions of this message have been removed]
    • Cody L
      Interesting. So it would just be a matter of diffusing the light source to hit the plate at a broader angle. I wonder if putting a curved sheet of plastic or
      Message 2 of 22 , Mar 6 6:34 AM
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        Interesting. So it would just be a matter of diffusing
        the light source to hit the plate at a broader angle.
        I wonder if putting a curved sheet of plastic or
        another material like mylar on the flip top might
        possibly do the job to refract the light enough. The
        platemaker was practically free so I want to explore
        all of my options on this before throwing it out. It
        is in excellent condition and is easy to adjust.

        What about increasing the exposure time? would that
        possibly help.

        Or adding some reflective metal pieces inside of the
        platemaker to bounce the light up at different angles.

        cody
        It's Fancy Letterpress Studio


        --- Gary Mordhorst <gary@...> wrote:

        > Hello Cody,
        >
        > The issue is that the offset plate maker has a pin
        > point light system. This type of light will cause a
        > letterpress plate to not have the shoulder, which
        > provides strength to the type form. A commercial
        > photopolymer plate maker uses a bank of high UV
        > bulbs, exposing the plate with a variety of angles
        > of light. This diffused light source creates the
        > shoulder on the type, and provides plate strength.
        >
        > You are going to find that small items, such as
        > periods and dot on lower case "i"s drop off during
        > the course of the press run.
        >
        > The light needs to be diffused, but I do not feel
        > that there is any safe way to diffuse the NuArc's
        > lamp.
        >
        >
        > Best Regards,
        >
        > Gary Mordhorst
        > AccuColor Plus, Inc.
        > 2134 W. Division
        > Chicago, IL 60622
        >
        > www.accucolor.com
        >
        > (773) 227-7788
        >
        >
        > Conventional Offset, Contemporary Letterpress, Foil
        > Stamping
        >
        > AccuColor Plus is a Certified Adobe Print Service
        > Provider
        >
        >
        >
        >
        > ----- Original Message -----
        > From: itsfancyletterpress
        > To: PPLetterpress@yahoogroups.com
        > Sent: Thursday, March 06, 2008 7:16 AM
        > Subject: [PPLetterpress] platemaking issues
        >
        >
        > I am super new to platemaking but things have gone
        > smoothly except for one issue.
        >
        > The kreen went on easily. I created a framework to
        > wrap it around and used the original
        > hardware to affix the screen to the frame of my
        > small Nuarc fliptop platemaker. I am hand
        > washing out the plates and outside of the time
        > spent with the nylon brush it is not too
        > difficult.
        >
        > I have had fun exposing small sample pieces and
        > recording the exposure times so I know
        > what to expect from the platemaker.
        >
        > The problem is on all of my plates the side walls
        > of the letters are at a 90 degree angle to the
        > letters top surface. The ones I purchase have an
        > angled slope.
        >
        > My question is how do I get my plate to taper
        > more? I am using a Jet plate 152 and a boxcar
        > deep relief base on my C&P's. I would love to get
        > this problem fixed tonight because I hae
        > spent a large fortune overthe years purchasing
        > finished plates from vendors.
        >
        > cody
        > It's Fancy Letterpress Studio
        >
        >
        >
        >
        >
        > [Non-text portions of this message have been
        > removed]
        >
        >



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      • John G. Henry
        For several years before I got my own polymer platemaker, I used a NuArc Fliptop platemaker for imaging photopolymer. I used a sheet of frosted mylar (used by
        Message 3 of 22 , Mar 6 7:23 AM
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          For several years before I got my own polymer platemaker, I used a
          NuArc Fliptop platemaker for imaging photopolymer. I used a sheet of
          frosted mylar (used by architects and drafts-people when they still did
          drawings by hand).

          Check out the mylar supplies at your local art supply store and buy a
          couple sheets. If you find you need more diffusion, stack them up above
          the Kreen to diffuse the light. I found I got good results with this,
          but you will have to slightly increase the exposure time to overcome
          the fall-off in light being transmitted.

          Here is a link to one supplier's version of this material:

          http://www.dickblick.com/zz232/04a/

          Blick sells this stuff for cutting stencils, & it should work for the
          purpose as well as anything.

          If you give it a try, please report back. Others will appreciate the
          feedback.
        • Cody L
          For greater coverage I am posting on PPletterpress and Briar Press Discussions. UPDATE: Platemaking experience with a NuArc FT18 platemaker. Ok, so here is a
          Message 4 of 22 , Mar 7 7:53 AM
          • 0 Attachment
            For greater coverage I am posting on PPletterpress and
            Briar Press Discussions.

            UPDATE: Platemaking experience with a NuArc FT18
            platemaker.

            Ok, so here is a recap and an update. I removed the
            glass top on the vacuum and replaced it with KREEN by
            creating a frame to hold it in and using the original
            hardware that was used with the glass plate. Until my
            12 step gauge comes in I have a 14 step gauge that I
            tried to use but it really is no help

            TEST 1: (6 - 3" x 3" pieces of polymer were exposed)
            I started out with a unit of 17 which was about
            00:01:45 for the test and run that up to a 79 unit
            exposure that was about 00:04:30. The longer exposure
            time increased the hardness of the plate but there was
            absolutely no shoulder to the artwork. I doubled the
            time for hardening. Commas and thin lines are weak but
            at the 79 units the plate is getting almost hard
            enough. At 99 units (approx 6 minutes) the letter
            forms bleed to a bold but shoulder thickness is still
            at a 90 degree angle to the artwork surface.

            TEST 2: (6 - 3" x 3" pieces of polymer were exposed)
            I purchased a DRAFTING FILM from the local art store.
            It has a frosted look but it is a smooth piece of
            plastic like material. I first taped it to the outside
            of the frame with a 1” gap between the FILM and the
            KREEN. With a 12 minute exposure there was very little
            hardening of the plate. Some letter forms even washed
            out during the first 3 minutes of hand washing the
            plate. Next I placed it between the KREEN and the
            NEGATIVE in the vacuum frame. I set the exposure to 99
            and did another test. There is a very slight shoulder
            now and the hardness is getting better but it still is
            a bit soft even after the washout and hardening in the
            platemaker for 10 minutes without the film. The
            problems from test 1 are still there with the commas
            and thin ruled lines.

            TEST 3: (6 - 3" x 3" pieces of polymer were exposed)
            I added a second film for testing to see if it
            increased the shoulder angle. I did a timed exposure
            because the units stop at 99 and that is roughly
            00:06:00 to 00:06:30 minutes on the bulbs current life
            cycle. I times an 8 minute, 10 minute and 12 minute
            exposure. The 12 minute exposure produced acceptable
            art without having the fonts grow to a bold weight.
            The shoulder however did not increase from the test 2
            results with the increased addition of the extra sheet
            of film.

            I even added tinfoil to the interior of the exposure
            unit in an attempt to reflect more of the light into
            the plate and broaden the shoulders but with no
            success. All it effected was the sensor for the
            interpolated (automatic) timer in which it turned it
            off quite soon after it was started due to increased
            light readings picked up.

            I am at this point very open to more suggestions on
            ways to increase the shoulder width. Please let me
            know if anyone has heard of ways around this with and
            offset platemaker or if you know of someone I can talk
            to who has successfully converted one I would love to
            talk to them!

            cody


            --- Cody L <itsfancyletterpress@...> wrote:

            > Interesting. So it would just be a matter of
            > diffusing
            > the light source to hit the plate at a broader
            > angle.
            > I wonder if putting a curved sheet of plastic or
            > another material like mylar on the flip top might
            > possibly do the job to refract the light enough. The
            > platemaker was practically free so I want to explore
            > all of my options on this before throwing it out. It
            > is in excellent condition and is easy to adjust.
            >
            > What about increasing the exposure time? would that
            > possibly help.
            >
            > Or adding some reflective metal pieces inside of the
            > platemaker to bounce the light up at different
            > angles.
            >
            > cody
            > It's Fancy Letterpress Studio
            >
            >
            > --- Gary Mordhorst <gary@...> wrote:
            >
            > > Hello Cody,
            > >
            > > The issue is that the offset plate maker has a pin
            > > point light system. This type of light will cause
            > a
            > > letterpress plate to not have the shoulder, which
            > > provides strength to the type form. A commercial
            > > photopolymer plate maker uses a bank of high UV
            > > bulbs, exposing the plate with a variety of angles
            > > of light. This diffused light source creates the
            > > shoulder on the type, and provides plate strength.
            > >
            > > You are going to find that small items, such as
            > > periods and dot on lower case "i"s drop off during
            > > the course of the press run.
            > >
            > > The light needs to be diffused, but I do not feel
            > > that there is any safe way to diffuse the NuArc's
            > > lamp.
            > >
            > >
            > > Best Regards,
            > >
            > > Gary Mordhorst
            > > AccuColor Plus, Inc.
            > > 2134 W. Division
            > > Chicago, IL 60622
            > >
            > > www.accucolor.com
            > >
            > > (773) 227-7788
            > >
            > >
            > > Conventional Offset, Contemporary Letterpress,
            > Foil
            > > Stamping
            > >
            > > AccuColor Plus is a Certified Adobe Print Service
            > > Provider
            > >
            > >
            > >
            > >
            > > ----- Original Message -----
            > > From: itsfancyletterpress
            > > To: PPLetterpress@yahoogroups.com
            > > Sent: Thursday, March 06, 2008 7:16 AM
            > > Subject: [PPLetterpress] platemaking issues
            > >
            > >
            > > I am super new to platemaking but things have
            > gone
            > > smoothly except for one issue.
            > >
            > > The kreen went on easily. I created a framework
            > to
            > > wrap it around and used the original
            > > hardware to affix the screen to the frame of my
            > > small Nuarc fliptop platemaker. I am hand
            > > washing out the plates and outside of the time
            > > spent with the nylon brush it is not too
            > > difficult.
            > >
            > > I have had fun exposing small sample pieces and
            > > recording the exposure times so I know
            > > what to expect from the platemaker.
            > >
            > > The problem is on all of my plates the side
            > walls
            > > of the letters are at a 90 degree angle to the
            > > letters top surface. The ones I purchase have an
            > > angled slope.
            > >
            > > My question is how do I get my plate to taper
            > > more? I am using a Jet plate 152 and a boxcar
            > > deep relief base on my C&P's. I would love to
            > get
            > > this problem fixed tonight because I hae
            > > spent a large fortune overthe years purchasing
            > > finished plates from vendors.
            > >
            > > cody
            > > It's Fancy Letterpress Studio
            > >
            > >
            > >
            > >
            > >
            > > [Non-text portions of this message have been
            > > removed]
            > >
            > >
            >
            >
            >
            >
            >
            ____________________________________________________________________________________
            > Looking for last minute shopping deals?
            > Find them fast with Yahoo! Search.
            >
            http://tools.search.yahoo.com/newsearch/category.php?category=shopping
            >
            >



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          • richard seibert
            All light, even after being diffused, travels in a straight line. When light travels out of one substance into another, its speed changes. This changes the
            Message 5 of 22 , Mar 7 8:07 AM
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              All light, even after being diffused, travels in a straight line.
              When light travels out of one substance into another, its speed
              changes. This changes the angle at which the ray travels. Think of a
              pencil in a glass of water. Every substance has an "index of
              refraction" which determines what this angel is. The characteristic
              slope of a well made photopolymer plate is the result of how
              photopolymer bends the light ray at the point it enters the
              photopolymer. This is also why film needs to be emulsion down.
              Nothing that happens to the light in-between being emitted by the
              electrons in the lamp and entering the film will effect what happens
              at the boundary between film and polymer. (Unless the intervening
              substance absorbs or reflects the necessary frequencies.)

              Too steep an angle is the result of not enough photons (or not enough
              photons of the right frequency) to fully polymerize the material.
            • Peter Fraterdeus
              Hi Cody, et alia ... Photons do travel in a straight line, and thus a broad light source will create a light cone, regardless of diffraction. Your argument
              Message 6 of 22 , Mar 7 10:03 AM
              • 0 Attachment
                Hi Cody, et alia

                Richard wrote:

                > The characteristic
                > slope of a well made photopolymer plate is the result of how
                > photopolymer bends the light ray at the point it enters the
                > photopolymer.


                Photons do travel in a straight line, and thus a broad light source
                will create a light cone, regardless of diffraction.
                Your argument implies that the source is an infinitely distant point.
                While the ray may bend due to the change in medium, I don't think
                that's the reason for the slope of the shoulder.

                As far as it goes, I am finding that the plate material from Boxcar
                produces very vertical shoulders. I think this is as much due to the
                fact that the yellow color absorbs the UV, and therefore the photons
                coming at an angle do not spread much beyond the point of entry. Those
                which enter at a shallow angle are absorbed before reaching the base.

                It seems to me that the shoulder angle is related to the photo-
                sensitivity of the polymer.
                I've been trying to find more in-depth technical info on all this,
                rather than apocryphal say-so, but the manufacturer's documentation
                (what little there is) seems to have been translated from Japanese
                into English leaving much to the imagination. Perhaps I'm looking up
                the wrong trees. Google likewise provides little elucidation. Of
                course there's Gerald's book, but why not reinvent the wheel every
                generation? Also, the plate materials seem to have changed since the
                copy I have was published.

                The problems I was having previously with loss of points and moving on
                the base had to do with too long wash-out, which would undermine the
                exposed points.

                I'm now using about 3.5 minute wash instead of five, which has done
                wonders for the stability of the fine points and rules. With the 'deep-
                relief' base it needs another minute or so to clean the base, but I'm
                washing as short a time as possible.

                Leaders and isolated dots and periods are solid cylinders. Not much
                shoulder, but they're hard as rocks, firmly seated on the base and
                seem to be printing fine. In fact, the older plate material I was
                using produced a wide shallow shoulder, the current stuff, with the
                clear untinted plastic base produces a nearly vertical shoulder.

                YMMV, of course....

                Peter Fraterdeus
                http://ExquisiteLetterpress.com
                http://dubuquebookarts.com





                On 7 Mar 2008, at 10:07 AM, richard seibert wrote:

                > All light, even after being diffused, travels in a straight line.
                > When light travels out of one substance into another, its speed
                > changes. This changes the angle at which the ray travels. Think of a
                > pencil in a glass of water. Every substance has an "index of
                > refraction" which determines what this angel is. The characteristic
                > slope of a well made photopolymer plate is the result of how
                > photopolymer bends the light ray at the point it enters the
                > photopolymer. This is also why film needs to be emulsion down.
                > Nothing that happens to the light in-between being emitted by the
                > electrons in the lamp and entering the film will effect what happens
                > at the boundary between film and polymer. (Unless the intervening
                > substance absorbs or reflects the necessary frequencies.)
                >
                > Too steep an angle is the result of not enough photons (or not enough
                > photons of the right frequency) to fully polymerize the material.
                >
              • Gerald Lange
                Peter I m not sure about this. I don t know that coloration has an effect though it may very well. The BASF plates have a very dense coloration to them. The
                Message 7 of 22 , Mar 7 10:17 AM
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                  Peter

                  I'm not sure about this. I don't know that coloration has an effect
                  though it may very well. The BASF plates have a very dense coloration to
                  them.

                  The plate materials have not changed since the book was written,
                  regardless of which edition you have. The only change I have seen in the
                  last decade and a half or so was the recent reformulation of the the
                  Toyobo Printight brand. There is a slight change in coloration (which I
                  cannot detect) and they expose quicker than the older formula.

                  That's about it, except for the newer filmless direct to plate sheet
                  photopolymer, not much has changed.

                  Gerald
                  http://BielerPress.blogspot.com

                  Peter Fraterdeus wrote:
                  > Hi Cody, et alia
                  >
                  > Richard wrote:
                  >
                  >
                  >> The characteristic
                  >> slope of a well made photopolymer plate is the result of how
                  >> photopolymer bends the light ray at the point it enters the
                  >> photopolymer.
                  >>
                  >
                  >
                  > Photons do travel in a straight line, and thus a broad light source
                  > will create a light cone, regardless of diffraction.
                  > Your argument implies that the source is an infinitely distant point.
                  > While the ray may bend due to the change in medium, I don't think
                  > that's the reason for the slope of the shoulder.
                  >
                  > As far as it goes, I am finding that the plate material from Boxcar
                  > produces very vertical shoulders. I think this is as much due to the
                  > fact that the yellow color absorbs the UV, and therefore the photons
                  > coming at an angle do not spread much beyond the point of entry. Those
                  > which enter at a shallow angle are absorbed before reaching the base.
                  >
                  > It seems to me that the shoulder angle is related to the photo-
                  > sensitivity of the polymer.
                  > I've been trying to find more in-depth technical info on all this,
                  > rather than apocryphal say-so, but the manufacturer's documentation
                  > (what little there is) seems to have been translated from Japanese
                  > into English leaving much to the imagination. Perhaps I'm looking up
                  > the wrong trees. Google likewise provides little elucidation. Of
                  > course there's Gerald's book, but why not reinvent the wheel every
                  > generation? Also, the plate materials seem to have changed since the
                  > copy I have was published.
                  >
                  > The problems I was having previously with loss of points and moving on
                  > the base had to do with too long wash-out, which would undermine the
                  > exposed points.
                  >
                  > I'm now using about 3.5 minute wash instead of five, which has done
                  > wonders for the stability of the fine points and rules. With the 'deep-
                  > relief' base it needs another minute or so to clean the base, but I'm
                  > washing as short a time as possible.
                  >
                  > Leaders and isolated dots and periods are solid cylinders. Not much
                  > shoulder, but they're hard as rocks, firmly seated on the base and
                  > seem to be printing fine. In fact, the older plate material I was
                  > using produced a wide shallow shoulder, the current stuff, with the
                  > clear untinted plastic base produces a nearly vertical shoulder.
                  >
                  > YMMV, of course....
                  >
                  > Peter Fraterdeus
                  > http://ExquisiteLetterpress.com
                  > http://dubuquebookarts.com
                  >
                  >
                  >
                  >
                  >
                  > On 7 Mar 2008, at 10:07 AM, richard seibert wrote:
                  >
                  >
                  >> All light, even after being diffused, travels in a straight line.
                  >> When light travels out of one substance into another, its speed
                  >> changes. This changes the angle at which the ray travels. Think of a
                  >> pencil in a glass of water. Every substance has an "index of
                  >> refraction" which determines what this angel is. The characteristic
                  >> slope of a well made photopolymer plate is the result of how
                  >> photopolymer bends the light ray at the point it enters the
                  >> photopolymer. This is also why film needs to be emulsion down.
                  >> Nothing that happens to the light in-between being emitted by the
                  >> electrons in the lamp and entering the film will effect what happens
                  >> at the boundary between film and polymer. (Unless the intervening
                  >> substance absorbs or reflects the necessary frequencies.)
                  >>
                  >> Too steep an angle is the result of not enough photons (or not enough
                  >> photons of the right frequency) to fully polymerize the material.
                  >>
                  >>
                  >
                  >
                  >
                  >
                • Cody L
                  First of all thanks for the information and your personal tests of the polymer and what it is doing for you. I did not think to stop the washout before you get
                  Message 8 of 22 , Mar 7 10:17 AM
                  • 0 Attachment
                    First of all thanks for the information and your
                    personal tests of the polymer and what it is doing for
                    you. I did not think to stop the washout before you
                    get to the clear base. I was just trying to match the
                    materials purchased from Boxcar on previous plate
                    orders.

                    I also appreciate the quick run down on light and
                    plate interaction. Yes the book in question is on its
                    way from a friend but it is not here now. I thank you
                    all for your patience!

                    With a hand washout i will probably have to be careful
                    with uniformity of the depth washed out and make sure
                    they properly dry before the hardening process.

                    If I were to create my own conversion to florescent UV
                    bulbs what should I look for. I have never searched
                    for the bulbs before just the entire platemaker. I
                    don't see that it would be very difficult to
                    accomplish a custom box that could sit on top of my
                    vacuum unit and have it hooked to a darkroom timer. I
                    have found bulbs online but I do not know if a UVA
                    tanning style bulg is what is required or a UV black
                    light bulb would be the correct style.

                    Thanks!

                    cody


                    --- Peter Fraterdeus <peterf@...> wrote:

                    > Hi Cody, et alia
                    >
                    > Richard wrote:
                    >
                    > > The characteristic
                    > > slope of a well made photopolymer plate is the
                    > result of how
                    > > photopolymer bends the light ray at the point it
                    > enters the
                    > > photopolymer.
                    >
                    >
                    > Photons do travel in a straight line, and thus a
                    > broad light source
                    > will create a light cone, regardless of diffraction.
                    > Your argument implies that the source is an
                    > infinitely distant point.
                    > While the ray may bend due to the change in medium,
                    > I don't think
                    > that's the reason for the slope of the shoulder.
                    >
                    > As far as it goes, I am finding that the plate
                    > material from Boxcar
                    > produces very vertical shoulders. I think this is as
                    > much due to the
                    > fact that the yellow color absorbs the UV, and
                    > therefore the photons
                    > coming at an angle do not spread much beyond the
                    > point of entry. Those
                    > which enter at a shallow angle are absorbed before
                    > reaching the base.
                    >
                    > It seems to me that the shoulder angle is related to
                    > the photo-
                    > sensitivity of the polymer.
                    > I've been trying to find more in-depth technical
                    > info on all this,
                    > rather than apocryphal say-so, but the
                    > manufacturer's documentation
                    > (what little there is) seems to have been translated
                    > from Japanese
                    > into English leaving much to the imagination.
                    > Perhaps I'm looking up
                    > the wrong trees. Google likewise provides little
                    > elucidation. Of
                    > course there's Gerald's book, but why not reinvent
                    > the wheel every
                    > generation? Also, the plate materials seem to have
                    > changed since the
                    > copy I have was published.
                    >
                    > The problems I was having previously with loss of
                    > points and moving on
                    > the base had to do with too long wash-out, which
                    > would undermine the
                    > exposed points.
                    >
                    > I'm now using about 3.5 minute wash instead of five,
                    > which has done
                    > wonders for the stability of the fine points and
                    > rules. With the 'deep-
                    > relief' base it needs another minute or so to clean
                    > the base, but I'm
                    > washing as short a time as possible.
                    >
                    > Leaders and isolated dots and periods are solid
                    > cylinders. Not much
                    > shoulder, but they're hard as rocks, firmly seated
                    > on the base and
                    > seem to be printing fine. In fact, the older plate
                    > material I was
                    > using produced a wide shallow shoulder, the current
                    > stuff, with the
                    > clear untinted plastic base produces a nearly
                    > vertical shoulder.
                    >
                    > YMMV, of course....
                    >
                    > Peter Fraterdeus
                    > http://ExquisiteLetterpress.com
                    > http://dubuquebookarts.com
                    >
                    >
                    >
                    >
                    >
                    > On 7 Mar 2008, at 10:07 AM, richard seibert wrote:
                    >
                    > > All light, even after being diffused, travels in a
                    > straight line.
                    > > When light travels out of one substance into
                    > another, its speed
                    > > changes. This changes the angle at which the ray
                    > travels. Think of a
                    > > pencil in a glass of water. Every substance has an
                    > "index of
                    > > refraction" which determines what this angel is.
                    > The characteristic
                    > > slope of a well made photopolymer plate is the
                    > result of how
                    > > photopolymer bends the light ray at the point it
                    > enters the
                    > > photopolymer. This is also why film needs to be
                    > emulsion down.
                    > > Nothing that happens to the light in-between being
                    > emitted by the
                    > > electrons in the lamp and entering the film will
                    > effect what happens
                    > > at the boundary between film and polymer. (Unless
                    > the intervening
                    > > substance absorbs or reflects the necessary
                    > frequencies.)
                    > >
                    > > Too steep an angle is the result of not enough
                    > photons (or not enough
                    > > photons of the right frequency) to fully
                    > polymerize the material.
                    > >
                    >
                    >
                    >



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                  • Gerald Lange
                    Cody I went back a ways to find this but your original post indicated you are using Jet 152s. If these are polyester-backed Boxcar supplied (KF152) I think
                    Message 9 of 22 , Mar 7 7:17 PM
                    • 0 Attachment
                      Cody

                      I went back a ways to find this but your original post indicated you
                      are using Jet 152s. If these are polyester-backed Boxcar supplied
                      (KF152) I think they are Toyobo brand, not Jet. I'm probably wrong but
                      as far as I can tell Jet doesn't make a plate in this configuration.

                      There has been problems with this particular configuration as reported
                      a number of times both here and on the Briar Discussion list.

                      I think you may be more successful by trying a different plate in your
                      testing.

                      In response to my questioning Harold Kyle did admit in a previous post
                      that he is using a custom technique for processing these plates. I'm
                      assuming you would need to know that information yourself in order to
                      process the plates correctly. Or all of your trials are to no avail.

                      Gerald
                      http://BielerPress.blogspot.com

                      --- In PPLetterpress@yahoogroups.com, Cody L <itsfancyletterpress@...>
                      wrote:
                      >
                      > First of all thanks for the information and your
                      > personal tests of the polymer and what it is doing for
                      > you. I did not think to stop the washout before you
                      > get to the clear base. I was just trying to match the
                      > materials purchased from Boxcar on previous plate
                      > orders.
                      >
                      > I also appreciate the quick run down on light and
                      > plate interaction. Yes the book in question is on its
                      > way from a friend but it is not here now. I thank you
                      > all for your patience!
                      >
                      > With a hand washout i will probably have to be careful
                      > with uniformity of the depth washed out and make sure
                      > they properly dry before the hardening process.
                      >
                      > If I were to create my own conversion to florescent UV
                      > bulbs what should I look for. I have never searched
                      > for the bulbs before just the entire platemaker. I
                      > don't see that it would be very difficult to
                      > accomplish a custom box that could sit on top of my
                      > vacuum unit and have it hooked to a darkroom timer. I
                      > have found bulbs online but I do not know if a UVA
                      > tanning style bulg is what is required or a UV black
                      > light bulb would be the correct style.
                      >
                      > Thanks!
                      >
                      > cody
                      >
                      >
                      > --- Peter Fraterdeus <peterf@...> wrote:
                      >
                      > > Hi Cody, et alia
                      > >
                      > > Richard wrote:
                      > >
                      > > > The characteristic
                      > > > slope of a well made photopolymer plate is the
                      > > result of how
                      > > > photopolymer bends the light ray at the point it
                      > > enters the
                      > > > photopolymer.
                      > >
                      > >
                      > > Photons do travel in a straight line, and thus a
                      > > broad light source
                      > > will create a light cone, regardless of diffraction.
                      > > Your argument implies that the source is an
                      > > infinitely distant point.
                      > > While the ray may bend due to the change in medium,
                      > > I don't think
                      > > that's the reason for the slope of the shoulder.
                      > >
                      > > As far as it goes, I am finding that the plate
                      > > material from Boxcar
                      > > produces very vertical shoulders. I think this is as
                      > > much due to the
                      > > fact that the yellow color absorbs the UV, and
                      > > therefore the photons
                      > > coming at an angle do not spread much beyond the
                      > > point of entry. Those
                      > > which enter at a shallow angle are absorbed before
                      > > reaching the base.
                      > >
                      > > It seems to me that the shoulder angle is related to
                      > > the photo-
                      > > sensitivity of the polymer.
                      > > I've been trying to find more in-depth technical
                      > > info on all this,
                      > > rather than apocryphal say-so, but the
                      > > manufacturer's documentation
                      > > (what little there is) seems to have been translated
                      > > from Japanese
                      > > into English leaving much to the imagination.
                      > > Perhaps I'm looking up
                      > > the wrong trees. Google likewise provides little
                      > > elucidation. Of
                      > > course there's Gerald's book, but why not reinvent
                      > > the wheel every
                      > > generation? Also, the plate materials seem to have
                      > > changed since the
                      > > copy I have was published.
                      > >
                      > > The problems I was having previously with loss of
                      > > points and moving on
                      > > the base had to do with too long wash-out, which
                      > > would undermine the
                      > > exposed points.
                      > >
                      > > I'm now using about 3.5 minute wash instead of five,
                      > > which has done
                      > > wonders for the stability of the fine points and
                      > > rules. With the 'deep-
                      > > relief' base it needs another minute or so to clean
                      > > the base, but I'm
                      > > washing as short a time as possible.
                      > >
                      > > Leaders and isolated dots and periods are solid
                      > > cylinders. Not much
                      > > shoulder, but they're hard as rocks, firmly seated
                      > > on the base and
                      > > seem to be printing fine. In fact, the older plate
                      > > material I was
                      > > using produced a wide shallow shoulder, the current
                      > > stuff, with the
                      > > clear untinted plastic base produces a nearly
                      > > vertical shoulder.
                      > >
                      > > YMMV, of course....
                      > >
                      > > Peter Fraterdeus
                      > > http://ExquisiteLetterpress.com
                      > > http://dubuquebookarts.com
                      > >
                      > >
                      > >
                      > >
                      > >
                      > > On 7 Mar 2008, at 10:07 AM, richard seibert wrote:
                      > >
                      > > > All light, even after being diffused, travels in a
                      > > straight line.
                      > > > When light travels out of one substance into
                      > > another, its speed
                      > > > changes. This changes the angle at which the ray
                      > > travels. Think of a
                      > > > pencil in a glass of water. Every substance has an
                      > > "index of
                      > > > refraction" which determines what this angel is.
                      > > The characteristic
                      > > > slope of a well made photopolymer plate is the
                      > > result of how
                      > > > photopolymer bends the light ray at the point it
                      > > enters the
                      > > > photopolymer. This is also why film needs to be
                      > > emulsion down.
                      > > > Nothing that happens to the light in-between being
                      > > emitted by the
                      > > > electrons in the lamp and entering the film will
                      > > effect what happens
                      > > > at the boundary between film and polymer. (Unless
                      > > the intervening
                      > > > substance absorbs or reflects the necessary
                      > > frequencies.)
                      > > >
                      > > > Too steep an angle is the result of not enough
                      > > photons (or not enough
                      > > > photons of the right frequency) to fully
                      > > polymerize the material.
                      > > >
                      > >
                      > >
                      > >
                      >
                      >
                      >
                      >
                      ____________________________________________________________________________________
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                      > know-it-all with Yahoo! Mobile. Try it now.
                      http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
                      >
                    • parallel_imp
                      ... Cody, there are many different grayscales. The right one here is a 21-step platemaker s grayscale, made by Stouffer, which is a transmission scale. There
                      Message 10 of 22 , Mar 10 7:06 AM
                      • 0 Attachment
                        --- In PPLetterpress@yahoogroups.com, Cody L <itsfancyletterpress@...>
                        wrote:
                        >

                        > [. . .] Until my 12 step gauge comes in I have a 14 step gauge
                        > that I tried to use but it really is no help


                        Cody, there are many different grayscales. The right one here is a
                        21-step platemaker's grayscale, made by Stouffer, which is a
                        transmission scale. There are other brands, but most maufacturer's
                        specs refer specifically to a 21-step scale, with target around step
                        16 (varies with mfr).
                        A 12-step scale (at least from Stouffer) is a camera (reflection)
                        scale and not useful for this purpose.
                        --Eric Holub, SF
                      • itsfancyletterpress
                        Gerald you are correct on the plates. I was trying to have a local guy source the plate material to see if it would save me a buck or two on shipping. Also
                        Message 11 of 22 , Mar 10 7:49 AM
                        • 0 Attachment
                          Gerald you are correct on the plates. I was trying to have a local guy source the plate
                          material to see if it would save me a buck or two on shipping.

                          Also you are correct Eric. With the lack of sleep this week I did a typo. I meant to type 21
                          not 12.

                          I built my own exposure unit Saturday and I plan a write up with pics to document my
                          progress. It will however take a couple of weeks. I also broke my NuArc platemaker,
                          smoked a 250V fuse, disassembled the whole thing and rewired it so just the vacuum
                          table was working off of the original switch. I am working today on 2 hours of sleep
                          because of a job I had to plate and print last night for a client pickup today. If you haven't
                          guessed letterpress is my weekend and night hobby.

                          I exposed a handful of plates but not to the perfection that I desired but with my washout
                          board on back order along with my sponge roller I had to improvise and it seemet to work
                          fine. Much to my wife's dismay (she was at church when I did it) I used our oven to speed
                          up drying time by putting the plates in there for 15 min at 130 degrees.

                          I still am working out issues with not enough shoulder for my liking but for a self
                          discovery crash course I am happy with the results. All in all I will be saving an average of
                          $80 to $100 in plate charges and shipping an order. which to me is worth the time and
                          energy in a hand washout plus I get to keep the negatives incase I want to reuse artwork
                          of have to remake a plate.

                          cody

                          --- In PPLetterpress@yahoogroups.com, "parallel_imp" <Megalonyx@...> wrote:
                          >
                          > --- In PPLetterpress@yahoogroups.com, Cody L <itsfancyletterpress@>
                          > wrote:
                          > >
                          >
                          > > [. . .] Until my 12 step gauge comes in I have a 14 step gauge
                          > > that I tried to use but it really is no help
                          >
                          >
                          > Cody, there are many different grayscales. The right one here is a
                          > 21-step platemaker's grayscale, made by Stouffer, which is a
                          > transmission scale. There are other brands, but most maufacturer's
                          > specs refer specifically to a 21-step scale, with target around step
                          > 16 (varies with mfr).
                          > A 12-step scale (at least from Stouffer) is a camera (reflection)
                          > scale and not useful for this purpose.
                          > --Eric Holub, SF
                          >
                        • typetom@aol.com
                          Hi Cody, If you use a glass top vacuum frame, you need to add matboard around the plate material within the frame, to support the glass across the whole
                          Message 12 of 22 , Mar 10 9:54 AM
                          • 0 Attachment
                            Hi Cody,
                            If you use a glass top vacuum frame, you need to add matboard around the
                            plate material within the frame, to support the glass across the whole surface.
                            Otherwise, glass will bend under the vacuum, and allow some light to bleed
                            irregularly around edges of the negative (which is not held in tight contact due
                            to the bend in the glass). Without the matboard support, the plate will have
                            swollen lines that print irregularly bold.

                            Depending on humidity in your area, a hand-held hair dryer may be adequate
                            for drying the plates. In Denver it only takes a couple of minutes. I shake the
                            surface water off the plate, use lung power to blow any further moisture off
                            the fine lines of the plate, and then use a small hand held dryer until the
                            steel backing is about too hot to handle. Insufficient drying will result in
                            a plate that continues to dry as it ages, which can result in severe curling.
                            (Some degree of this is likely anyhow, but can be minimized by sufficient
                            drying before the second exposure).

                            Good contact with the negative, precise timing for exposure, and carefully
                            limited time in the washout, are the most critical factors. I have not found
                            the Stoeffer scale as useful as others attest, but recommend trial and error
                            and practice, with careful observation. The various polymer materials
                            available, variations of density in the negatives, variations of intensity of
                            different light sources (which may be set up at different distances in a homemade
                            system), all will affect the best exposure time for you to use. Different kinds
                            of lines, fine details, dots that need more support, reverse lines that may
                            fill in when exposed normally, all may require slightly different exposure
                            times. Experience and careful observation are necessary whether you are looking
                            at the results of a calibrated Stoeffer test or actual results on the job.

                            A few other notes:
                            Hand washout is limited by the size of brush you can handle, which affects
                            how long a large plate has to be kept in the water as it is being washed. Since
                            the polymer material is hardened by exposure from the surface down to the
                            base, surface details will separate from the base if the plate is allowed to
                            stay in the water too long. Limiting washout to under 4 or 5 minutes, I rarely
                            have broken or wavy lines or missing serifs. But that means I have to stop
                            washout of larger plates before they are completely clean. Not as pretty a
                            finished plate, but usually not a problem on the press. Most of the plates I
                            make are card/invitation size, maybe 5x7 max, though occasionally I have done an
                            8x10 or larger -- I'm limited by the size of my sink as well!

                            My light source is a box of 4 UV fluorescent tubes, sitting about an inch
                            and a half above the glass of the vacuum frame. Cost me about $50 for the
                            bulbs, everything else was free scrap stuff except the cost of the brush and a
                            Stoeffer scale that I don't use. Steel backed Miraclon plates from Gene Becker
                            in NYC cost about $300 for 10 large sheets. Very lucky to find a good cutter
                            with leverage to cut the steel plates. Patmag aluminum backing blocks from NA
                            Graphics, with a little masking tape on the edges of the plates anyhow to
                            make sure nothing moves during printing. Most jobs are done on my 10x15 C&P,
                            more difficulty keeping registration with the Vandercook SP15. If I were
                            starting new, I'd probably go with the Boxcar system, particularly because of the
                            difficulty of cutting the steel backed material and the expense of magnetic
                            backing blocks which still need to be taped and watched for registration
                            problems anyhow.

                            No direct experience with washout of the polyester backed material, nor with
                            other light sources.

                            Most of my photopolymer work has been custom commercial job printing,
                            hundreds of jobs, probably a dozen years since I started making plates myself (26
                            years since I started letterpress). I still use handset type for most of my
                            poetry projects and for jobs when it can be done. The main reasons for using
                            polymer plates are 1) client familiarity with computer fonts they like; 2)
                            flexibility in design work that can be done with scanned images, calligraphy,
                            clip-art, and manipulation or adjustments that can be done with proofs of
                            limited or worn metal type and cuts; 3) the strength of polymer plates compared
                            with lead type, when printing on paper that has sticks and flowers etc, and when
                            trying to please clients who want sculpture as much as readable text.

                            I love it all. Best wishes,
                            Tom

                            Tom Parson
                            Now It's Up To You Publications
                            157 S. Logan, Denver CO 80209
                            (303) 777-8951 home
                            (720) 480-5358 cell phone
                            http://members.aol.com/typetom



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                            [Non-text portions of this message have been removed]
                          • Cody L
                            Thanks Tom for your insight! Very informative. I fit my vacuum table with Kreen and it works really well to get the plate and negative sucked up together. That
                            Message 13 of 22 , Mar 10 11:26 AM
                            • 0 Attachment
                              Thanks Tom for your insight! Very informative. I fit
                              my vacuum table with Kreen and it works really well to
                              get the plate and negative sucked up together. That is
                              the first thing that I did before I started my
                              experiments. I don't know about the 21 step scale
                              either. I am still waiting on mine but I have gauged
                              them to look like the plates I have purchased from
                              Boxcar and am getting pretty close to the same color.

                              I probably need to be more patient on the the drying.
                              I did forget about a plate in the oven last night and
                              pulled it out after about 35 minutes. The thin lines,
                              corps and some of the type got too soft and started to
                              move around.

                              cody



                              --- typetom@... wrote:

                              > Hi Cody,
                              > If you use a glass top vacuum frame, you need to add
                              > matboard around the
                              > plate material within the frame, to support the
                              > glass across the whole surface.
                              > Otherwise, glass will bend under the vacuum, and
                              > allow some light to bleed
                              > irregularly around edges of the negative (which is
                              > not held in tight contact due
                              > to the bend in the glass). Without the matboard
                              > support, the plate will have
                              > swollen lines that print irregularly bold.
                              >
                              > Depending on humidity in your area, a hand-held hair
                              > dryer may be adequate
                              > for drying the plates. In Denver it only takes a
                              > couple of minutes. I shake the
                              > surface water off the plate, use lung power to blow
                              > any further moisture off
                              > the fine lines of the plate, and then use a small
                              > hand held dryer until the
                              > steel backing is about too hot to handle.
                              > Insufficient drying will result in
                              > a plate that continues to dry as it ages, which can
                              > result in severe curling.
                              > (Some degree of this is likely anyhow, but can be
                              > minimized by sufficient
                              > drying before the second exposure).
                              >
                              > Good contact with the negative, precise timing for
                              > exposure, and carefully
                              > limited time in the washout, are the most critical
                              > factors. I have not found
                              > the Stoeffer scale as useful as others attest, but
                              > recommend trial and error
                              > and practice, with careful observation. The various
                              > polymer materials
                              > available, variations of density in the negatives,
                              > variations of intensity of
                              > different light sources (which may be set up at
                              > different distances in a homemade
                              > system), all will affect the best exposure time for
                              > you to use. Different kinds
                              > of lines, fine details, dots that need more support,
                              > reverse lines that may
                              > fill in when exposed normally, all may require
                              > slightly different exposure
                              > times. Experience and careful observation are
                              > necessary whether you are looking
                              > at the results of a calibrated Stoeffer test or
                              > actual results on the job.
                              >
                              > A few other notes:
                              > Hand washout is limited by the size of brush you can
                              > handle, which affects
                              > how long a large plate has to be kept in the water
                              > as it is being washed. Since
                              > the polymer material is hardened by exposure from
                              > the surface down to the
                              > base, surface details will separate from the base if
                              > the plate is allowed to
                              > stay in the water too long. Limiting washout to
                              > under 4 or 5 minutes, I rarely
                              > have broken or wavy lines or missing serifs. But
                              > that means I have to stop
                              > washout of larger plates before they are completely
                              > clean. Not as pretty a
                              > finished plate, but usually not a problem on the
                              > press. Most of the plates I
                              > make are card/invitation size, maybe 5x7 max, though
                              > occasionally I have done an
                              > 8x10 or larger -- I'm limited by the size of my sink
                              > as well!
                              >
                              > My light source is a box of 4 UV fluorescent tubes,
                              > sitting about an inch
                              > and a half above the glass of the vacuum frame. Cost
                              > me about $50 for the
                              > bulbs, everything else was free scrap stuff except
                              > the cost of the brush and a
                              > Stoeffer scale that I don't use. Steel backed
                              > Miraclon plates from Gene Becker
                              > in NYC cost about $300 for 10 large sheets. Very
                              > lucky to find a good cutter
                              > with leverage to cut the steel plates. Patmag
                              > aluminum backing blocks from NA
                              > Graphics, with a little masking tape on the edges of
                              > the plates anyhow to
                              > make sure nothing moves during printing. Most jobs
                              > are done on my 10x15 C&P,
                              > more difficulty keeping registration with the
                              > Vandercook SP15. If I were
                              > starting new, I'd probably go with the Boxcar
                              > system, particularly because of the
                              > difficulty of cutting the steel backed material and
                              > the expense of magnetic
                              > backing blocks which still need to be taped and
                              > watched for registration
                              > problems anyhow.
                              >
                              > No direct experience with washout of the polyester
                              > backed material, nor with
                              > other light sources.
                              >
                              > Most of my photopolymer work has been custom
                              > commercial job printing,
                              > hundreds of jobs, probably a dozen years since I
                              > started making plates myself (26
                              > years since I started letterpress). I still use
                              > handset type for most of my
                              > poetry projects and for jobs when it can be done.
                              > The main reasons for using
                              > polymer plates are 1) client familiarity with
                              > computer fonts they like; 2)
                              > flexibility in design work that can be done with
                              > scanned images, calligraphy,
                              > clip-art, and manipulation or adjustments that can
                              > be done with proofs of
                              > limited or worn metal type and cuts; 3) the strength
                              > of polymer plates compared
                              > with lead type, when printing on paper that has
                              > sticks and flowers etc, and when
                              > trying to please clients who want sculpture as much
                              > as readable text.
                              >
                              > I love it all. Best wishes,
                              > Tom
                              >
                              > Tom Parson
                              > Now It's Up To You Publications
                              > 157 S. Logan, Denver CO 80209
                              > (303) 777-8951 home
                              > (720) 480-5358 cell phone
                              > http://members.aol.com/typetom
                              >
                              >
                              >
                              > **************It's Tax Time! Get tips, forms, and
                              > advice on AOL Money &
                              > Finance.
                              > (http://money.aol.com/tax?NCID=aolprf00030000000001)
                              >
                              >
                              > [Non-text portions of this message have been
                              > removed]
                              >
                              >



                              ____________________________________________________________________________________
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                            • typetom@aol.com
                              In a message dated 3/10/2008, itsfancyletterpress@yahoo.com writes: I did forget about a plate in the oven last night and pulled it out after about 35
                              Message 14 of 22 , Mar 10 3:38 PM
                              • 0 Attachment
                                In a message dated 3/10/2008, itsfancyletterpress@... writes:

                                I did forget about a plate in the oven last night and pulled it out after
                                about 35 minutes. The thin lines, corps and some of the type got too soft and
                                started to move around.


                                Hi Cody,
                                Thin lines that seem to have moved or become wavy more likely are a sign of
                                being too long in the washout. I've never had that happen because of my
                                hairdryer! I suppose the polymer could melt, but I know it can get soft and
                                distorted if it is in the water too long.
                                Tom





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                                [Non-text portions of this message have been removed]
                              • itsfancyletterpress
                                I think I am going to take one of my small space heaters and build a little metal box with a couple of trays for air drying. That way the air is circulating
                                Message 15 of 22 , Mar 11 6:41 AM
                                • 0 Attachment
                                  I think I am going to take one of my small space heaters and build a little metal box with a
                                  couple of trays for air drying. That way the air is circulating the entire time past the plates.
                                  The oven was an "in a pinch" solution that I will not be using again. The crop marks did
                                  not go wavy but did in fact start to flatten out in the oven. The one that was left in by
                                  accident did in fact go soft on the type and art. The ones that were in there just 10
                                  minutes did not have issues.

                                  I made 9 small palates out of which one needed to be remade due to my neglect. I only
                                  had one comma drop on the short run of 400 impressions so I get to put that mark in by
                                  hand tonight. There are 6 pieces total in a 2 color to the wedding set I printed. I took pics
                                  of the steps along the way but there are things I will be improving on my exposure unit
                                  over the summer.

                                  cody

                                  --- In PPLetterpress@yahoogroups.com, typetom@... wrote:
                                  >
                                  >
                                  >
                                  > In a message dated 3/10/2008, itsfancyletterpress@... writes:
                                  >
                                  > I did forget about a plate in the oven last night and pulled it out after
                                  > about 35 minutes. The thin lines, corps and some of the type got too soft and
                                  > started to move around.
                                  >
                                  >
                                  > Hi Cody,
                                  > Thin lines that seem to have moved or become wavy more likely are a sign of
                                  > being too long in the washout. I've never had that happen because of my
                                  > hairdryer! I suppose the polymer could melt, but I know it can get soft and
                                  > distorted if it is in the water too long.
                                  > Tom
                                  >
                                  >
                                  >
                                  >
                                  >
                                  > **************It's Tax Time! Get tips, forms, and advice on AOL Money &
                                  > Finance. (http://money.aol.com/tax?NCID=aolprf00030000000001)
                                  >
                                  >
                                  > [Non-text portions of this message have been removed]
                                  >
                                • parallel_imp
                                  ... Tom, are you talking about a commercially made vacuum frame, a pressure frame, or something homemade? I don t see how glass would bend in a NuArc vacuum
                                  Message 16 of 22 , Mar 11 4:35 PM
                                  • 0 Attachment
                                    --- In PPLetterpress@yahoogroups.com, typetom@... wrote:
                                    >

                                    > If you use a glass top vacuum frame, you need to add matboard around
                                    > the plate material within the frame, to support the glass across the
                                    > whole surface. Otherwise, glass will bend under the vacuum, and
                                    > allow some light to bleed irregularly around edges of the negative
                                    > (which is not held in tight contact due to the bend in the glass).
                                    > Without the matboard support, the plate will have swollen lines that
                                    > print irregularly bold.

                                    Tom, are you talking about a commercially made vacuum frame, a
                                    pressure frame, or something homemade?
                                    I don't see how glass would bend in a NuArc vacuum frame. There is
                                    a flexible rubber blanket beneath the glass, and as the air is sucked
                                    out, the blanket is pulled up to the glass. The glass does not distort
                                    in my experience. Proper use of relief valve will leave no air between
                                    glass, neg, and plate, and full vacuum is indicated by appearance of
                                    Newton's Rings.
                                    I could understand this problem if you were talking about a
                                    pressure frame like those Amergraph units using foam rubber, or
                                    something not using the normal vacuum blanket.
                                    But if air bubbles do form in a vacuum frame, it may be from not
                                    using either matte-emulsion film or a matte plate, or failing to
                                    back-trim plates to remove burrs and swollen edges.
                                    --Eric Holub, SF
                                  • typetom@aol.com
                                    In a message dated 3/11/2008 4:36:05 P.M. Mountain Standard Time, Megalonyx@aol.com writes: Tom, are you talking about a commercially made vacuum frame, a
                                    Message 17 of 22 , Mar 12 2:18 AM
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                                      In a message dated 3/11/2008 4:36:05 P.M. Mountain Standard Time,
                                      Megalonyx@... writes:

                                      Tom, are you talking about a commercially made vacuum frame, a
                                      pressure frame, or something homemade?
                                      I don't see how glass would bend in a NuArc vacuum frame. There is
                                      a flexible rubber blanket beneath the glass, and as the air is sucked
                                      out, the blanket is pulled up to the glass. The glass does not distort
                                      in my experience. Proper use of relief valve will leave no air between
                                      glass, neg, and plate, and full vacuum is indicated by appearance of
                                      Newton's Rings.
                                      I could understand this problem if you were talking about a
                                      pressure frame like those Amergraph units using foam rubber, or
                                      something not using the normal vacuum blanket.
                                      But if air bubbles do form in a vacuum frame, it may be from not
                                      using either matte-emulsion film or a matte plate, or failing to
                                      back-trim plates to remove burrs and swollen edges.
                                      --Eric Holub, SF



                                      Hi Eric,
                                      I am using an old NuArc vacuum frame (with a homemade bank of UV bulbs in a
                                      box placed on top of the glass), not sure of the model or any possible NuArc
                                      variants of design. The problems I had were not due to air bubbles or burrs.
                                      The plates often had an irregular small area that printed more boldly than the
                                      rest of the plate -- the end of a long line, one edge of a text block. No
                                      apparent rhyme or reason, no regular pattern as to where the bolder edge would
                                      appear. The irregular differences in the plate were hard to see when looking
                                      at the surface of the plate, but it showed on printing. At first I thought it
                                      was a problem with my rollers or my trucks, perhaps causing irregular inking
                                      more heavily down the sides of the type. New rollers, metal trucks, very
                                      careful adjustments, no difference.

                                      The answer is that the glass was bending in my vacuum frame, allowing some
                                      slight distortion of contact with the negative and thus an irregular exposure
                                      and thus swelling in the plate. Mat board placed around the plate material
                                      within the frame completely solved the problem. The mat board gives support for
                                      the glass across the size of the frame. I can see no other explanation. While
                                      the rubber blanket beneath the glass is pulled up by the vacuum, the glass
                                      apparently distorts slightly around the edges of the plate material if it is
                                      not supported. Differences in the positions of plate materials in the frame
                                      may account for the irregular location of the problem on different plates.
                                      Maybe my rubber blanket is old enough to be too stiff to shape to the contours of
                                      the plate?

                                      (I'm not clear what you mean by: "Proper use of relief valve will leave no
                                      air between glass, neg, and plate, and full vacuum is indicated by appearance
                                      of Newton's Rings." I'm not aware of a "relief valve" in my system. I do
                                      think I know what you mean by Newton's Rings... I suspect there is some
                                      difference in use of a vacuum pump at Denver's elevation and thin air, but it seems to
                                      maintain sufficient full contact between the negative and the plate material
                                      except for the problem described above.)

                                      Meanwhile, thanks for your on-going excellent observations on all aspects of
                                      photopolymer plates and printing. Best wishes,
                                      Tom

                                      Tom Parson
                                      Now It's Up To You Publications
                                      157 S. Logan, Denver CO 80209
                                      (303) 777-8951 home
                                      (720) 480-5358 cell phone
                                      http://members.aol.com/typetom



                                      **************It's Tax Time! Get tips, forms, and advice on AOL Money &
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                                    • parallel_imp
                                      ... Tom, the vacuum frames made by NuArc that are designed specifically for platemaking (fliptops, 26-1K etc.) have a relief valve or bleed valve. You leave it
                                      Message 18 of 22 , Mar 12 7:48 AM
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                                        --- In PPLetterpress@yahoogroups.com, typetom@... wrote:
                                        >
                                        >
                                        > (I'm not clear what you mean by: "Proper use of relief valve will
                                        > leave no air between glass, neg, and plate, and full vacuum is
                                        > indicated by appearance of Newton's Rings." I'm not aware of a
                                        > "relief valve" in my system.

                                        Tom, the vacuum frames made by NuArc that are designed specifically
                                        for platemaking (fliptops, 26-1K etc.) have a relief valve or bleed
                                        valve. You leave it open until the blanket is pulled up to the glass,
                                        then slowly close it. That slower draw allows all the air to be
                                        removed without any remaining pockets.
                                        The NuArc contact frames designed for general contact printing
                                        (with no integral light source) don't have the relief valve in the
                                        stock vacuum system, which draws down in a few seconds. I suppose
                                        that's because only a few layers of film were normally placed in the
                                        contact unit, while the platemaker might have to support heavier
                                        contents such as a step-and-repeat board.
                                        Other than the valve, the frames function identically. It wouldn't
                                        be hard to add a valve, just cut the hose leading to the frame and
                                        insert a needle valve the appropriate size. It might simplify your
                                        process, if I'm right. But cardboard is cheap, and if a system works,
                                        it works.
                                        --Eric Holub, SF
                                      • parallel_imp
                                        ... Tom, here s another way to look at the problem of photopolymer plates in a glass-faced vacuum frame. Many photopolymer plates are smooth and tacky, and
                                        Message 19 of 22 , Mar 12 10:07 AM
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                                          --- In PPLetterpress@yahoogroups.com, typetom@... wrote:
                                          >
                                          > . . .
                                          > The answer is that the glass was bending in my vacuum frame, allowing
                                          > some slight distortion of contact with the negative and thus an
                                          > irregular exposure and thus swelling in the plate. Mat board placed
                                          > around the plate materialwithin the frame completely solved the
                                          > problem. The mat board gives support forthe glass across the size
                                          > of the frame.

                                          Tom, here's another way to look at the problem of photopolymer plates
                                          in a glass-faced vacuum frame. Many photopolymer plates are smooth and
                                          tacky, and stick easily to smooth-surfaced films. If the drawdown in
                                          the frame is fast, a bond can form at one or more edges of the plates
                                          before the air is drawn out of the interior of the plate, causing
                                          out-of-contact bubbles. The rubber blanket pulling the plate up might
                                          also apply more pressure at the edges. Using the bleed valve allows
                                          for a soft contact, removing more air before hard contact is achieved.
                                          Your cardboard is definitely relieving the pressure at the edge, and
                                          would also be allowing more air to escape. But I think the forces at
                                          work are moving upward to the glass, not downward to the plate.
                                          The problem of plate tackiness is addressed in many manufacturer's
                                          instructions, specifying matte-emulsion film, or detacking powder
                                          (silicon spray is another possibility). I'm now using the Rigilon HX
                                          which itself has a matte-emulsion for better drawdown to any kind of
                                          film. This isn't an issue with a crene-covered frame, since you can
                                          brayer or burnish out any air bubbles, but with glass it is definitely
                                          a problem to overcome, with various possible solutions.
                                          --Eric Holub, SF
                                        • typetom@aol.com
                                          Something new (something old & new) every day. Thanks, Eric. My nuArc vacuum frame has a name plate but no model number, no bleed valve, but a pressure gauge
                                          Message 20 of 22 , Mar 12 1:32 PM
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                                            Something new (something old & new) every day. Thanks, Eric.

                                            My nuArc vacuum frame has a name plate but no model number, no bleed valve,
                                            but a pressure gauge on the line. It has a glass top hinged within a metal
                                            frame, with a vacuum area about 21.5 x 25.5. Not clear whether it ever had a
                                            light attached -- it appears to have been part of a larger apparatus. The
                                            vacuum space below the glass is sufficient to handle plate material, more than a
                                            just contact prints.

                                            Meanwhile, I do dust the plate material with powder to prevent it from
                                            grabbing the negative. I don't think air bubbles are the cause of the exposure
                                            irregularities I experienced. Uneven pressure on the plate and negative at the
                                            edges of the plate (which I have assumed involves some slight bending of the
                                            glass) seems the likely explanation. Mat board around the plate seems to solve
                                            the problem completely. Whatever works!

                                            Thanks,
                                            Tom

                                            Tom Parson
                                            Now It's Up To You Publications
                                            157 S. Logan, Denver CO 80209
                                            (303) 777-8951 home
                                            (720) 480-5358 cell phone
                                            http://members.aol.com/typetom



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