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11954Re: Photopolymer separating from polyester backer

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  • bielerpr
    Aug 2, 2010
      Glenwood

      This article might help

      http://bielerpressxi.blogspot.com/2006/03/on-scales-and-lamps.html

      You would not want to swap out a ballast unless one is malfunctioning. They last far longer than bulbs. If your bulbs all turn on, your ballasts are working. If a bulb or bulbs are acting erratically you likely would have a wiring/connection problem.

      That suggestion re: back exposure is likely in reference to the KF152 plates not the KF95. The KF152 is a bit softer and thicker plate and that little trick is used to strengthen the relief structure. I doubt the KF95 would benefit from this as it does not share the problems that have been related regarding the KF152. Note that sheet photopolymer plates are already back-exposed by the manufacturer.

      Gerald
      http://BielerPress.blogspsot.com



      --- In PPLetterpress@yahoogroups.com, "idgradstudent" <glenwoodemorris@...> wrote:
      >
      > Thanks to Harold, Gerald, Peter, et al for the help and suggestions.
      >
      > I will have to do some testing at the edge of my exposure unit with my Stouffer scale and see if I am getting different results there, which seems likely.
      >
      > I have had intermittent problems with overexposure in certain areas as well, which has kept me from just increasing my exposure time. I am guessing this is the "hot spots" that some bulbs can develop over time?
      >
      > Is there any detrimental effect to new bulbs if you replace just the bulbs rather than swapping the bulbs and the ballasts?
      >
      > I will try exposing the back of the plate for 20 seconds to see if it might be a temporary workaround.
      >
      > Glenwood Morris
      >
      > Oslo Press Inc.
      >
      > --- In PPLetterpress@yahoogroups.com, Harold Kyle <harold@> wrote:
      > >
      > > You're using all the right equipment and materials. The details on your
      > > plate are likely detaching because they haven't received enough light during
      > > the main exposure. The photopolymer material hasn't hardened all the way
      > > down to the base. It separates during drying while it contracts--it has
      > > nothing to hold on with.
      > >
      > > The bulbs most likely need replacing on your machine as you've surmised. In
      > > the meantime you may have to keep increasing your main exposure to
      > > compensate for their lack of output. Have you done a Stouffer test at the
      > > edge of your bulbs recently? Fluorescent tubes put out less and less light
      > > as they age. But you already knew this. Is this what you're asking?
      > >
      > > Harold
      > >
      > > On Mon, Aug 2, 2010 at 12:47 AM, idgradstudent <glenwoodemorris@>wrote:
      > >
      > > >
      > > >
      > > > Harold,
      > > >
      > > > I'm using an older Jet A3 platemaker with analog controls (as opposed to
      > > > the newer ones with digital controls).
      > > >
      > > > It uses a bank of lights.
      > > >
      > > > The separation is happening at some point between post-washout rinsing and
      > > > the end of post-exposure. It is not 100% consistent but I will be examining
      > > > more closely between drying and post-exposure in the future.
      > > >
      > > > I am using silver emulsion film, yes.
      > > >
      > > >
      > > > Glenwood Morris
      > > >
      > > > Oslo Press Inc.
      > > >
      > > > --- In PPLetterpress@yahoogroups.com <PPLetterpress%40yahoogroups.com>,
      > > > Harold Kyle <harold@> wrote:
      > > > >
      > > > > 5 minutes shouldn't be too long for the washout. You're fine there.
      > > > >
      > > > > What type of platemaker do you use? Point light source or a bank of
      > > > lights?
      > > > >
      > > > > The photopolymer will separate for lots of reasons. It sounds like this
      > > > is
      > > > > happening during processing? During washout or during drying?
      > > > >
      > > > > Finally, are you using silver emulsion film? It sounds like you are. Just
      > > > > checking.
      > > > >
      > > > > Would love to help but need more info.
      > > > >
      > > > > Harold
      > > > >
      > > > > On Sun, Aug 1, 2010 at 11:09 PM, idgradstudent <glenwoodemorris@
      > > > ...>wrote:
      > > >
      > > > >
      > > > > >
      > > > > >
      > > > > > More info:
      > > > > >
      > > > > > Fresh KF95 plates.
      > > > > >
      > > > > > I have a lot of "variables" like oldish brushes, and older bulbs that
      > > > > > require a long exposure time (9 minutes according to my stouefer
      > > > scale). So
      > > > > > it would certainly be easy to dismiss my issues by saying "Hey, go do
      > > > some
      > > > > > basic maintenance to your platemaker" and you would be right. Aside
      > > > from
      > > > > > this relatively recent issue the plates have been good so I have opted
      > > > to
      > > > > > spend funds on other more pressing issues as a longer exposure time
      > > > does not
      > > > > > cost me much since I only make plates for myself and the cost for new
      > > > bulbs
      > > > > > and ballasts is not insignificant.
      > > > > >
      > > > > > My washout is probably too long (5 minutes), I will back it off and see
      > > > if
      > > > > > that works. When I first acquired the machine I established my exposure
      > > > > > times with a scale and my washout times through trial and error but I
      > > > may
      > > > > > have just gone too far. Generally if I lose anything to this problem it
      > > > is a
      > > > > > crop mark on the edge of a plate, but recently I started losing thin
      > > > script
      > > > > > text and fine lines in graphics if they were also near the edge of the
      > > > > > plate.
      > > > > >
      > > > > > My question included limited info as I wanted to know what the root
      > > > cause
      > > > > > of photopolymer/polyester separation was rather than have folks just
      > > > tell me
      > > > > > to do maintenance that is not really an option right now.
      > > > > >
      > > > > >
      > > > > > Glenwood Morris
      > > > > >
      > > > > > Oslo Press Inc.
      > > > > >
      > > > > > --- In PPLetterpress@yahoogroups.com <PPLetterpress%40yahoogroups.com><PPLetterpress%
      > > > 40yahoogroups.com>,
      > > >
      > > > > > "idgradstudent" <glenwoodemorris@> wrote:
      > > > > > >
      > > > > > > I did some searching and found several discussions about plates that
      > > > have
      > > > > > separated; i.e. the photopolymer has detached from the polyester
      > > > backer.
      > > > > > >
      > > > > > > What I did not find in the discussion was any agreed upon conclusions
      > > > > > about why exactly this happens (or I simply missed it).
      > > > > > >
      > > > > > > Does anyone know what causes this to occur? I am currently having
      > > > > > problems with this with some of my plates and was wondering if there
      > > > was a
      > > > > > "known cause" before I just start changing things and hoping for the
      > > > best.
      > > > > > >
      > > > > > > Thanks,
      > > > > > >
      > > > > > > Glenwood Morris
      > > > > > >
      > > > > > > Oslo Press Inc.
      > > > > > >
      > > > > >
      > > > > >
      > > > > >
      > > > >
      > > > >
      > > > >
      > > > > --
      > > > > ---
      > > > > Boxcar Press
      > > > > 501 W. Fayette St. #222
      > > > > Syracuse, NY 13204
      > > > > www.boxcarpress.com
      > > > >
      > > >
      > > >
      > > >
      > >
      > >
      > >
      > > --
      > > ---
      > > Boxcar Press
      > > 501 W. Fayette St. #222
      > > Syracuse, NY 13204
      > > www.boxcarpress.com
      > >
      >
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