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Problem Description or Explanation
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Possible Cause / Solution
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Poor reproduction of high-light dots
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Fogging of unprocessed plate
Solution
- Use a new plate and handle the plate under a yellow
safety lamp.
Poor vacuum contact
Solution
- Check the vacuum frame and the condition of the
rubber sealing.
- Extend the time of vacuum contact.
- Insert clear film strips between the film and the plate
in order to obtain an air channel.
Exposure time is too long
Solution
- Check whether the UGRA grey scale (6-8 microns)
is correctly visible on the plate.
Insufficient density of the film positive
Solution
- Reduce the exposure time.
Insufficient development of the plate
Solution
- Develop the plate again by hand.
When you use an automatic processor check
following items:
- The brush pressure is even and not too weak
- The pre-treatment shower works correctly
- PP-1 fluid is full and fresh
- The used brushes are not old (limit. 20.000 passes)
- Temperature of PP-1 (approx. 40°C)
Plate is too old
Solution
- Use a new plate. Usually, plates which are older than
12 months become difficult to be developed. Toray
guarantees a proper function of the plate up to
6 months after delivery.
Too low room temperature / humidity (hand-development of positive/negative type)
Solution
Develop the plate under normal room conditions. When
the room temperature or humidity is too low, it is difficult
to develop the plate correctly.
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Problem Description or Explanation
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Possible Cause / Solution
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Poor reproduction of shadow dots and silicone pealing
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Poor vacuum contact
Solution
- Check the vacuum frame and the condition of the
rubber sealing.
- Extend the time of vacuum contact.
- Insert clear film strips between the film and the plate
in order to obtain an air channel.
Exposure time is too long
Solution
- Check whether the UGRA grey scale (6-8 microns)
is correctly visible on the plate.
Insufficient density of the film positive
Solution
- Reduce the exposure time.
Too aggressive development
Solution
- During hand-development, don´t rub the plate too
aggressively. For machine development, check
whether the brush pressure is even and not
too strong.
Too high humidity
Solution
When the humidity is higher than 80%, a silicone pealing
may occur.
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Problem Description or Explanation
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Possible Cause / Solution
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Dirt and film edge reproduction
on the plate
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Insufficient cleaning of frame glass and film
Solution
- Remove dirt by wiping the glass by a damp sponge
and a little soap to eliminate the static build-up.
Exposure time is too long
Solution
- Check whether the UGRA grey scale (6-8 microns)
is correctly visible on the plate.
Others
Solution
Expose the background areas by using proper masks.
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Problem Description or Explanation
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Possible Cause / Solution
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Scratches on the printing plate
(in vertical direction)
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Incorrect plate making
Solution
- Refer to our attached user´s manual.
Incorrect mounting of plate into the printing press
Solution
- Take care not to touch the plate at the saftey bar
of the printing machine.
Hard particles on the rollers
Solution
- Check the ink form rollers and remove hard particles
or wash-up the rollers.
Incorrect materials used for the hickey picker
Solution
- Use soft rubber (silicone) roller as a hickey picker.
Hard rubber may scratch the silicone surface of
the plate.
Dirt on the hickey picker roller
Solution
Clean the hickey picker roller.
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Problem Description or Explanation
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Possible Cause / Solution
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Image reappears after deletion
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Image reappears after deletion Deletion fluid was put on oily surface
Solution
- Clean the the image areas with PC-1 and dry the
area before using the deletion fluid.
Old deletion fluid ST-1
Solution
- Use new ST-1 and renew the applicator tip frequently.
Inefficient ST-1 coating
Solution
- Apply a coating of moderate thickness.
Drying time of deletion fluid ST-1 is too short
Solution
- Correct drying time of ST-1 is 3 min. Use hot air
if necessary.
Frequent plate cleaning of deleted areas
Solution
- Avoid to clean deleted areas excessively.
Usage of wrong plate cleaning solvents
Solution
Use the correct plate cleaner PC-1.
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Problem Description or Explanation
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Possible Cause / Solution
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Scumming at the edges of deleted areas
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Rough surface of the ST-1 coating
Solution
- Rub off the coating gently with a soft, wet wipe with
PC-1 and apply fresh ST-1.
Too thick ST-1 coating
Solution
- Use a fresh ST-1 with a new applicator tip. Dilute
ST-1 with PC-1 and spread it by using a small
piece of wipe.
Drying time of deletion fluid ST-1 is too short
Solution
Correct drying time of ST-1 is 3 min. Use hot air if necessary.
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Problem Description or Explanation
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Possible Cause / Solution
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Scratches on the plate
(horizontal direction)
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Incorrect cleaning of the plate in the press
Solution
Wash-up the plate by using a clean soft wipe containing
sufficient plate cleaner PC-1. Apply stop-out solution ST-1
when necessary.
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Problem Description or Explanation
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Possible Cause / Solution
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Background scumming (toning)
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High printing press temperature
Solution
- Adjust the air condition in the printing room and
cool the press by chilled air. Modern waterless
offset presses have the option to cool the plate
cylinder and/or the vibration rollers by independent
water circuits.
Unsuitable ink for the press temperature condition (viscosity is too low)
Solution
- Check the press temperature and use an ink of
higher viscosity. Add 0.5 - 1% of anti-toning
additive if necessary.
Too much ink on the rollers
Solution
- Reduce the amount of ink by sheeting off.
Oily residue on the rollers / wrong roller washing solvent
Solution
- Wash rollers with PC-1. Check whether machine
oil drops into the rollers during press operation.
Incorrect roller adjustment
Solution
- Minimize the form-roller / vibration roller pressure
(of the last form roller).
- Reduce the pressure of the last form roller onto
the plate.
- Check for unevenness of the roller pressure over
the total roller length.
Plate flapping at the gripping edge
Solution
- Check if the plate grip is tight.
Large image coverage
Solution
Use ink of higher viscosity
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Problem Description or Explanation
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Possible Cause / Solution
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Poor ink laydown / Hollow dots /
Poor gloss
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Low press temperature
Solution
- Warm-up the press by running the machine without
feeding of sheets/cards.
Usage of unsuitable ink for the press temperature
(ink viscosity and tack is too high)
Solution
- Check the press temperature and use an ink type
which suits accordingly. Viscosity can be adjusted
by adding reducer to the ink (max. 5%).
Cold ink can
Solution
- Warm up the ink cans up to 20°C (70°F) before
taking the ink out.
Insufficient agitation of ink
Solution
- Agitate the ink well in the ink duct of the press.
Close the ink duct keys a little and increase the
rotation angle of the ink duct roller accordingly.
- Use a harder type of ink rollers ( 40-45° shore A).
Insufficient quantity of ink on the rollers
Solution
- Increase the volume of ink on the rollers.
Unsuitable blanket or its underpacking
Solution
- Use a quick release, semi-compressible blanket type.
Check for the thickness of blanket underpacking and
use paper sheets of calibrated thickness.
Low impression pressure
Solution
- Increase the impression pressure.
Bad form roller condition
Solution
Check the quality of the form roller surface and make sure
that it is smooth.
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Problem Description or Explanation
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Possible Cause / Solution
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Ghosting effect (happens mostly in solid image areas containing white patterns)
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Pressure of vibration rollers to form roller is too low
Solution
- Check the contact pressure nip and increase the
pressure if necessary.
Linear movement of vibration roller is not suitable
Solution
- Reduce or increase the length of the linear vibration
roller movement. It might be necessary to leave the
standard settings of the press in some cases,
depending on the characteristic/design of the image.
Starting point of linear vibration roller movement
is not suitable
Solution
Change the beginning of linear vibration roller movement,
relative to the plate cylinder position.
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Problem Description or Explanation
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Possible Cause / Solution
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Hickeys
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Paper dust accumulates on blanket and plate
Solution
- Use proper sheet/card material which is not dusty.
- Do not use waste sheets to start and to adjust
the press.
- Use a soft hickey picker rubber roller.
Hard particles coming off both ends of rollers
Solution
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Problem Description or Explanation
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Possible Cause / Solution
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Poor wet-on-wet trapping
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Poor laydown of ink
Solution
- See our explanation at ´Poor laydown of ink´.
- Adjust tack between the inividual colours.
- Check printing density of the previous colour
and reduce the ink level.
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Problem Description or Explanation
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Possible Cause / Solution
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Back trapping
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Too much ink printed on the sheet
Solution
- Keep the normal ink density during printing process
and do not try to match the proof by using too
much ink.
- Check the ink lay-down quality first and consider
our mentioned recommendations before increasing
the ink level too much.
- Check your films and plates and study our
explanation about ´Poor reproduction of
high-light dots´.
Incorrect tacks between the individual colours
Solution
Adjust tack between the inividual colours.
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Problem Description or Explanation
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Possible Cause / Solution
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Plate wear is too fast
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Pressure is too high
Solution
- Check the plate packing (pressure) and blanket
packing (pressure) and re-adjust it according
to press specification.
Abrasive spray powder
Solution
Avoid to use too much spray powder.
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