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9482Re: [PPLetterpress] Re: platemaking issues

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  • Cody L
    Mar 10, 2008
      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.


      --- 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
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      > [Non-text portions of this message have been
      > removed]

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